- Email: [email protected]
Satisfaction with and usage of a hand neuroprosthesis
206
Satisfaction With and Usage of a Hand Neuroprosthesis Kathryn Stroh Wuolle, OTR/L, CHT, Clayton L. Van Doren, PhD, Anne M. Bryden, OTRIL, R Hunter Peckham, PhD, Michael W Keith, MD, Kevin L. Kilgore, PhD, Julie H. Grill, MS ABSTRACT. Stroh Wuolle K, Van Doren CL, Bryden AM, Peckman PH, Keith MW, Kilgore KL, Grill JH. Satisfaction with and usage of a hand neuroprosthesis. Arch Phys Med Rehabil 1999;80:206-13. Objective: To measure the satisfaction with, clinical impact of, and use of an implantable hand neuroprosthesis. Setting: Eight different medical centers. Participants: Thirty-four individuals with spinal cord injuries at the C5 or C6 motor level. Interventions: Participants were implemented with a hand neuroprosthesis that provides grasp and release. The neuroprosthesis includes a surgically implanted stimulator, implanted electrodes sutured to the hand and forearm muscles, and an externally mounted controller. Main Outcome Measure: A survey was mailed to study participants, who were asked to respond to statements such as “If I had it to do over, I would have the hand system implanted again,” using a 5-level Likert scale (“strongly agree” to “strongly disagree”). Results: Eighty-seven percent of participants were very satisfied with the neuroprosthesis, 88% reported a positive impact on their life, 87% reported improvements in activities of daily living, and 81% reported improved independence. Participants reported using the neuroprosthesis a median of 5.5 days per week; 15 participants used the neuroprosthesis 7 days per week, and 5 participants reported not using the device. Conclusions: The neuroprosthesis was used by most participants. The neuroprosthesis performed satisfactorily, increased users’ ability to perform activities of daily living and independence, and improved their quality of life. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation
P
ROVIDING INCREASED hand function for individuals with tetraplegia is an important rehabilitation objective. Hanson and Franklin1 asked a group of tetraplegic men to rank-order functional losses associated with their injury, and 76% of the men ranked the loss of arm and hand function
From the Functional Electrical Stimulation Center, MetroHealth Medical Center (Ms. Stroh Wuolle, Drs. Peckham, Keith, Kilgore); the Cleveland VA Medical Center (Ms. Stroh Wuolle, Ms. Bryden, Drs. Peckham, Keith, Kilgore); the Department of Orthopaedics and Biomedical Engineering, Case Western Reserve University (Drs. Van Dorm, Peckham, Keith, Kilgore); and NeuroControl Corporation (Ms. Grill), Cleveland, OH. Submitted for publication October 29, 1997. Accepted in revised form July 24, 1998. Supported in part by the Rehabilitation Research and Development Service of the Department of Veterans Affairs (Merit Review BOl l-6RA) and the National Institotes of General Health Clinical Research Center at MetroHealth Medical Center (MOlRR00080). A commercial party having a direct financial interest in the results of the research supporting this article has conferred or will confer a benefit upon one or more of the authors. Reprint requests to Laura Polacek, MetroHealth Medical Center, H601, 2500 MetroHealth Drive, Cleveland, OH 44109-1998. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003.9993/99/X002-4702$3.00/0
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highest-above the loss of leg, bladder and bowel, or sexual function. The latter were ranked highest by only X.1%, 13.5%, and 2.7% of the study group, respectively. A neuroprosthesis” has been developed that provides lateral and palmar grasp to persons with C5 and C6 motor level spinal cord injuries. The neuroprosthesis consists of both implanted and external components (fig 1). The receiver-stimulator is surgically implanted on the participant’s chest, in a location similar to placement of a pacemaker. Eight electrodes are passed subcutaneously from the receiver-stimulator down the arm and sutured to muscles in the forearm and hand (generally the extensor digitorum communis, extensor pollicis longus, abductor pollicis brevis, adductor pollicis, flexor pollicis longus, flexor digitorum superficialis, flexor digitorum profundus). Hand opening and closing are controlled through voluntary motion of the opposite shoulder. As individuals elevate and depress the shoulder, the motion is detected by a shoulder-position sensor mounted on the chest. This signal is transmitted to an external microprocessor unit that sends stimulus control signals to the implanted receiverstimulator (via radio frequency transmission). In turn, the implant receiver-stimulator generates the appropriate pattern of electrical pulses to open and close the hand.2-4 The efficacy of the neuroprosthesis has been measured in several ways, including pinch strength, range of motion, ability to grasp and release, and performance of activities of daily living.5-7 Batavia and Hammer8 however, state that the most important basis for evaluating an assistive device is whether it meets the needs of the disabled consumer. Several authors studied the relationship of device characteristics to consumer preference and found four important criteria for success: (1) effectiveness: how well the device enhances the users functional capability; (2) affordability: how much it costs to purchase, maintain, and repair the device; (3) operability: how easy the device is to operate; and (4) dependability: how long the device operates without reduced performance or breakdown. Additional criteria include, ranked in order of importance, portability, durability, compatibility, flexibility, ease of maintenance, securability, learnability, personal acceptance, physical comfort, supplier repair, physical security, consumer repair, and ease of assembly.8 Phillips and Zhao9 found four factors that were significantly related to abandoning the device: change in user needs or priorities (including improvement in functional abilities and change in personal activities or goals), easeof obtaining the device (the easier a device is to obtain, the more likely it is to be abandoned), poor device performance (including inadequate effectiveness, reliability, durability, comfort, safety, and ease of use), and lack of consideration of user opinion in selection. Phillips and Zhaog also found that most abandonment occurs within the first year or after 5 years of use. Phillips and Zhao9 and Batavia and Hammers emphasized the importance of soliciting consumer involvement and understanding the long-term needs of consumers in reducing abandonment and enhancing consumer satisfaction. Failure to do so often leads to abandonment of the technology, as reported by many authors.8,10-14According to Scherer and McKee,‘* rates of abandonment have been reported from as low as 8% to as high as 75%, with 30% being average. Studies of satisfaction with and use of conventional devices
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External Components
Receiver Stimulator
External Control Unit
Fig 1. The neuroprosthesis consists internal components (receiver-stimulator,
of external components (external 8 epimysial electrodes).
for upper-extremity rehabilitation highlight more specific requirements for successful deployment. Follow-up studies of functional orthosis use by individuals with tetraplegia, for example, indicate usage rates that range from 39% to 89%,9,15-2o although usage was not measured consistently in these studies. Functional splints are generally useful for eating with utensils, writing, grasping objects, using a telephone, and typing.17 Nichols and colleagues18however, found that some individuals wear the splints only to perform specific activities. Wise and colleagues20believe that continued use of an orthosis is due to early intervention (within 2 weeks of admission) and extensive training (at least 4 months of inpatient training). In their study, outpatients showed the lowest acceptance rates, and only 20% continued to use the devices prescribed. Individuals also would not use the orthosis if their functional ability had increased or decreased, or if the orthosis fit poorly, weighed too much, interfered with wheelchair propulsion, was difficult to don and doff, or was unreliable: unattractive or too expensive.15J6J8 Prostheses used after amputations have had similar abandonment problems. Silcox and colleagues21found a 50% rejection rate of a myoelectric prosthesis and a 32% rejection rate for a conventional prosthesis. Reasons for rejection included the excessive weight of the prosthesis, its sluggish responsiveness, its poor durability and fit, and difficulty in operating it. Other authors have explored the relationship between technology acceptance and personal characteristics.22s23Disability acceptance, motivation, goal-directedness, perceived life tasks, effort-reward balance, and life satisfaction are all related to positive attitudes toward devices. Scherer23 also found that assistive devices are used more often and successfully the longer the person has to adjust to their spinal cord injury (SCI), the younger the person is at injury, and the higher the degree of malleabihty. As with any new technology, it is imperative that user satisfaction and rates of usage be assessedearly in the clinical deployment of the neuroprosthesis. Such assessmentwill make
control
unit,
shoulder
position
transducer)
and
surgically
implanted
possible improvement of the device based on consumer input, and help to refine the criteria used to select the most appropriate potential users. Because authors of each of the referenced studies designed their own evaluation tools and did not incorporate formal follow-up protocols, there was no standard or accepted evaluation tool for use in our follow-up with the neuroprosthesis recipients. Therefore, we designed a custom survey to measure whether the neuroprosthesis was actually used in everyday life, to measure whether participants were satisfied with the device, to determine the impact of the neuroprosthesis on participants’ lives, to determine the change in activities of daily living (ADL), independence, and occupation, and to record participants’ comments and suggestions. METHODS All of the procedures were approved by the institutional review boards of the participating institutions. Subjects Candidates for the hand grasp neuroprosthesis included individuals with the following characteristics: (1) an international classification in group 0, 1, or 2, (ocular [0] or cutaneous [C] afferent inputs% as described in table 1, and an American Spinal Injury Association (ASIA) C.5 or C6 motor leveLz5 (2) neurologically stable, (3) skeletally mature, (4) at least 12 months after injury, (5) good passive range of motion of the upper extremity, (6) sufficient shoulder and elbow strength, along with adequate postural support to position the hand functionally once implemented with a hand neuroprosthesis, (7) strong, electrically excitable hand flexion and extension muscles or a muscle that could be transferred to substitute for a weak stimulated response, (8) an adequate attendant support system to assist with follow-up, (9) independent wheelchair mobility, (10) good general health, (11) an optimistic and motivated state of mind, with realistic goals and an adequate adjustment to their Arch
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Table
1: International Classification in Individuals With
Sensibility*
“0”
Group
or “Cu”
0
1 2
or “Cu” or “Cu”
for Surgery Tetraplegia
No muscle
Elbow for
transfer Brachioradialis Extensor carpi radialis
flexion
forearm
and
supina-
tion Wrist
extension extension
longus
“0”
or “Cu”
3
Extensor radialis
carpi brevis
Wrist
“0”
or “Cu”
4
Pronator
teres
Wrist extension pronation
“0”
or “Cu”
“0”
or “Cu”
5 6
Flexor Finger
“0”
or “Cu”
7
Thumb
“0”
or “Cu”
8
Partial digital flexors
“0”
or “Cu”
9
Lacks
“0”
or “Cu”
X
Exceptions
carpi radialis extensors
and
Wrist flexion Extrinsic finger extension
extensors
only
Extrinsic thumb extension
intrinsics
Extrinsic flexion
finger (weak)
Extrinsic flexion
finger
* “0” or “Cu” refers to ocular afferent input or cutaneous afferent input (ie, IOmm Z-point discrimination threshold on thumb and index finger). + Motor description assumes that all listed muscles are grade 4 (Medical Research Council) or better, and each group has listed muscle plus muscles of all weaker groups.
disability. Participants who were international classification group 3 (ie, grade 4 extensor carpi radialis longus and extensor carpi radialis brevis) were not enrolled routinely, and were given the option of tendon transfer surgery for improved hand function or a neuroprosthesis.26-29Some of these characteristics (eg, optimism and motivation) were not assessedformally. Forty-two participants had been implemented with the neuroprosthesis at eight clinical institutions worldwide at the time the survey was performed. (As of this writing, there are 104 neuroprosthesis recipients worldwide.) Six participants were too early in their postsurgical rehabilitation to be included in the study. One participant died for reasons unrelated to the implant, and another had the implant removed secondary to an infection from a pressure sore.3oBoth of these participants had used the neuroprosthesis regularly but are not included in this study. The remaining 34 participants who were assessedhad completed their rehabilitation training in use of the neuroprosthesis and were at least 1 year after surgery, including at least 6 months of home use. Six participants were motor level C4K.5 (C4 one arm, C5 the other), 12 were CYC5, 10 were C5K6, and 6 were C6/C6. Table 2 presents ASIA motor levels and international classifications by arm. Eight women and 26 men participated, ranging in age at injury from 13 to 53 years old (median, 25 years) and in age at implantation from 16 to 57 years (median, 30 years). The time between injury and implantation ranged from 14 months to more than 32 years (median, 4 years), and the time between the implant and the survey ranged from 14 months to 9 years (median, 5.2 years). Thirty-one participants had adjunctive surgeries on their upper extremities such as a tendon transfer (30 had surgery on their neuroprosthesis arm and 15 on the other arm). Impairment Measures All participants completed functional evaluations (a standardized test of grasp and release6 and measurements of pinch Arch
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strength and range of motion) at several time points as part of the clinical trial5 but data reported here were collected from the rehabilitation and training period following implantation of the neuroprosthesis or the l-year postimplantation follow-up.
Function
below suitable
SATISFACTION
of the Hand
Characteristics
elbow “0” “0”
NEUROPROSTHESIS:
Satisfaction Survey The main objective of this study was to measure the impact of, satisfaction with, and use of a hand neuroprosthesis as perceived by participants. The survey was initially designed by the authors, applied in a pilot study, and subsequently modified by the authors and investigators from the manufacturer of the neuroprosthesis,a who sponsored its FDA-monitored clinical trials. Participants received the survey by mail and an independent market research firm, under contract, retrieved the answers from the participants by telephone. In Part 1 of the survey, participants were asked to respond to statements such as “If I had it to do over, I would have the hand system implanted again,” using a 5-level Likert scale (strongly disagree, disagree, neutral, agree, or strongly agree). Figure 2 lists an abbreviated version of each of the statements used in the survey (six statements on general satisfaction; four on life impact; six on ability to perform activities; five on independence; three on impact on work, school, home maintenance, and childcare; and one on appearance). The remaining questions (Part 2) asked participants to: report on average how many days a week they used the device; list the activities for which they used their neuroprosthesis; comment on any negative responses to the statements in Part 1; cite any reasons for not using the neuroprosthesis; estimate the amount of attendant care time needed before and after the implant; and to make any general comments or criticisms. Three participants refused to complete the survey, and one participant was not administered the survey because the participant lived in Croatia. For completeness, though, the first author telephoned these four participants to determine their frequency of use and their reasons for not donning the system. The partial data are used in the summaries of usage statistics and participant characteristics and in hand impairment comparisons to provide a more complete picture of all the participants and to try to ensure that those refusing to be surveyed were represented. Data Analysis Analyses were primarily descriptive because the study population was small and the survey has not been validated formally. Classification and regression trees31(S-plus, version 4.0) were used to explore associations between each of the Likert scale responses or the frequency of use and 13 predictor variables, including demographic variables (gender, age at implant and injury, time between implant and surgery, motor level) and measures of impairment (lateral, palmar, and five-finger grasp Table
2: Number
Classification
ASIA
motor
of Arms
Classification
Group
NP Arm
c4 c5 C6
0 19 15
21 7
0 1 2
6 15 12
11 16 6
3
1
1
23 11
27 7
level
International
Sensation
Abbreviation:
in Each
0 cu NP, neuroprosthesis.
Other
Arm
6
HAND
Category:
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% Responses:
Questions:
General Satisfaction
I wouldrecommendthe NPto otherswith SC1 I am satisfiedwith my NP The NP is reliable I wouldhavethe NP implantedagain TheNP hasmet my expectations I would pay for the NP if I had the money Life Impact (TheNP hasnegativelyimpactedmy life) TheNP hasimprovedmy qualityof life The NPhaspositivelyimpactedmy life I havebenefitedfrom the NP ADL are easierto perform ADL I canperformmoreADL I feel moreconfidentperformingADL I performADL more“normally” I performADL faster Independence I am ableto function moreindependently I requirelessassistance from others I uselessadaptiveequipment I am more comfortableout in the community Occupation Positiveimpacton workischoolperformance Positiveimpacton potentialto work/school Positiveimpacton homemaintenance/child care Appearance The appearanceof my handhasimproved Key: Fig 2. Percentage of participants disagree” as per key). Questions life impact” have been inverted
responding to questions are listed in abbreviated for consistency with the
n
strongly agree
neutral
0
disagree
in Pat-t 1 of the satisfaction survey at each of 5 levels (“strongly form and were not presented in the order shown. The responses rest of the questions. NP, neuroprosthesis.
forces; grasp-release test performance) with and without the neuroprosthesis. Ordinary regressions (Microsoft Excel version 6.0) were also performed between each of the outcome variables and each of the predictor variables. These analyses suggested that motor level had the most robust overall effect on the Likert responses and usage. Differences among the motor levels for the Likert responses were analyzed simply using contingency tables and x2 tests. Usage was not analyzed similarly since the number of responses in each category was small (0 to 4, typically). RESULTS Part 1 Participants responded very positively. The Likert scale responses to the statements in Part 1 are presented in figure 2 (see also fig 4A). The statements are grouped into six areas: general satisfaction, life impact, ADL, independence, occupation, and appearance. Responses within each group were pooled to calculate overall percentages. General satisfaction. Participants were very satisfied with the neuroprosthesis, in general; 87% of the responses in this group of questions were positive (“agree” or “strongly agree”). All but one of the participants (97%) would recommend the neuroprosthesis to others, 90% were satisfied with the neuroprosthesis, 90% stated the neuroprosthesis was reliable, 87% would have the surgery again, 80% felt the neuroprosthesis met their expectations, and 77% would pay for the neuroprosthesis if they had the money. Life impact. Eighty-eight percent of the responses were positive for life impact. Participants stated that the neuroprosthesis improved their quality of life (90%), made a positive impact
q
strongly disagree
agree” to “strongly regarding “negative
on their life (87%) (did not make a negative impact, 90%), and provided a benefit (83%). ADL. Eighty-seven percent of the responses regarding changes in ADL were positive. Ninety-three percent of participants could perform ADL easier, 93% could perform more ADL such as painting and shaving, 90% had increased confidence when performing ADL, 83% could perform ADL more “normally,” and 73% could perform ADL faster. Independence. Overall, 81% of the responses to the independence statements were positive. Eighty-seven percent of the participants reported that they were able to function more independently, 83% used less adaptive equipment, 87% required less assistancefrom others, and 67% felt more comfortable out in the community alone. Participants were also asked to estimate (in hours) the attendant time required daily before and after receiving the neuroprosthesis, a somewhat more objective measure than the Likert responses. The difference in attendant time (ie, time required with the neuroprosthesis minus the time required without the neuroprosthesis) varied widely by participant, with a median of 0 hours per day (ranging from a decrease of 11 attendant hours per day to an increase of 1 hour). Nineteen participants stated that the neuroprosthesis did not change the actual hours of attendant time, even though 16 of these participants felt they were able to function more independently. This could indicate that participants considered other factors when asked about independence, or that participants only thought about their morning and evening attendant, who usually still came to assistthem even after they received the neuroprosthesis, or that their attendant came the same number of hours but performed different activities. Occupation. Figure 2 reports the percentage of positive “occupation” responses (74%) for only those participants who Arch
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worked at the time of the survey (or went to school, II = 13) and those who intended to work (or intended to go to school, n = 9). There was a large number of neutral responses for impact on home maintenance and child care, with only 34% positive responses. Overall, 57% of participants’ responses to occupation questions were positive. Appearance. The appearance of the participants’ hands were not expected to change much. Overall, 87% of the participants felt their hand appearance was unchanged or improved. Part 2 The second part of the survey asked questions regarding frequency of device use and the activities for which the device was used, and solicited comments regarding changes in quality of life, suggestions for improvements, reasons for not donning the neuroprosthesis, and general comments. All 34 participants were queried regarding frequency of use and reasonsfor nonuse. Not all participants cited activities or provided comments, Usage. Average usage is plotted in figure 3 for all 34 participants combined and for each motor level. Participants reported using the neuroprosthesis a median of 5.5 days per week, but ranged from 15 participants (44%) who donned the neuroprosthesis 7 days per week to 5 participants (15%) who donned the neuroprosthesis less than 1 day per week. Twentyfour of 34 participants (71%) reported using their neuroprosthesis 4 or more days per week. The range of usage for C4K5, C5/C5, and C6K6 levels was the same, (0 to 7 days per week), whereas the C5lC6 group used the neuroprosthesis most regularly (4 to 7 days per week), with most participants (800) reporting daily use. Activities. Participants were asked to list activities for which they used their neuroprosthesis. The activities reported varied across participants. The most frequently reported activities included eating, drinking, shaving, brushing teeth, brushing hair, writing, operating a computer, and playing games. Other mentioned activities included preparing food, using a corkscrew, shopping, applying make-up, face-washing, typing, using a telephone, filing, picking up books, turning pages, using computer disks, paying bills, using a fax machine, increasing work area, reaching into drawers, using remote controls, playing audio cassettes, using video tapes, using power machines, painting, sketching, building models, smoking, opening doors, assisting children with homework, and picking up miscellaneous items. Quality of life comments. Eighteen participants made positive comments about how their quality of life changed, one participant responded neutrally (no change in quality of life) and one responded negatively. All positive comments were related to the effectiveness of the device and included reports of: increased independence (12 responses), increased ability to do ADL (10 responses), increased confidence and self esteem (5 responses), ability to perform activities more “normally” (3 responses), increased ease in performing tasks (2 responses), and decreased use of adaptive equipment (1 response). The one negative comment about quality of life regarded lack of effectiveness (still needing help for most activities) and difficulty with maintenance in that the participant required additional assistanceto don the neuroprosthesis. Suggested improvements. The improvements participants stated they wanted to see in the neuroprosthesis included increasing dependability (8 responses), making the external devices smaller and lighter (6 responses),making the neuroprosthesis easier to don (6 responses), reducing the number of cables (5 responses), making more of the components implantable (2 responses), making the movement more precise (2 Arch
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0
l-3
4-6
7
Days Donned Fig 3. Distribution of usage rates, ie, the percentage of participants reporting each rate, (A) pooled across all participants and (B) pooled across participants within each motor level. The number of participants included in each level is indicated in the graphs.
responses), including more muscles for triceps and bilateral systems (2 responses), and making it easier to control (1 response). Reasons for not donning. Participants were asked why they did not use the neuroprosthesis if they did not. After stating the reason(s), participants were asked to rank their reasons for not donning the device from the most frequent (rank 1) to the least frequent. Twelve participants stated “not applicable” since they used the system every day. The remaining 22 participants’ responses were separated into nonusers (5) and users (17) so that we can pay special attention to those individuals who have abandoned the technology. The median rank participants assigned to each reason and the median days donned per week across those who gave that reason are presented to estimate an approximate importance of each
HAND
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reason. A reason given by a 6-day-per-week user is probably less important overall than one cited by a l-day-per-week user. There were three reasons nonusers gave that were unique: (1) revision surgery was needed (2 nonusers, median rank = 1.5) (2) the neuroprosthesis hand was contracted and no longer worked (1 nonuser, rank 1; the patient stated that this occurred because he did not use splints or complete range of motion exercises), and (3) for the same C4K5 individual, his shoulder became painful upon using his arm for activities (1 nonuser, rank 2). The other reasons nonusers gave were similar to, but stronger than, reasons cited by users. For example, one nonuser said he was depressed about life and was not getting out of bed, while a user said that he had low demands because of lifestyle. Both statements reflect problematic motivation, but the nonuser’s condition was more severe. The remaining reasons participants gave for not using the neuroprosthesis were: (1) their attendant did not have time (7 users, median rank = 2, median usage = 4), (2) they did not use their system when they were in bed because of illness, lack of an attendant, or just choosing to stay in bed on a given day (6 users, 1 nonuser, median rank = 1, median usage = 4), (3) the system was not needed or they could perform same activities without it (6 users, 1 nonuser, median rank = 2, median usage = 3), (4) they had skin irritations from the tape or transmitting coil (6 users, 1 nonuser, median rank = 2, median usage = 4), (4) they were not in the habit or mood (6 users, median rank = 2, median usage = 4), (6) the participant did not have time (5 users, median rank = 2, median usage = 5), (7) the system malfunctioned (3 users, median rank = 2, median usage = 5) (8) the appearance was an issue (3 users, median rank = 2, median usage = 6), (9) they had motivational problems, reporting depressed or low demands because of their lifestyle (1 user, 1 nonuser, rank = 1, median usage = 0.5), and (10) “other” (1 user, rank = 1, usage = 7). Comments. Participants were encouraged to share any comments or criticisms regarding the neuroprosthesis. Of 14 participants who responded, 12 responded positively, stating they were happy with the device and its effectiveness. One participant responded positively but also discussed improving dependability. Finally, one participant responded negatively stating the neuroprosthesis was costly and not effective. Participant characteristics. The exploratory analyses showed that, of all the personal characteristics, only motor level consistently accounted for differences in Likert-level responses to questions in Part 1 of the survey. The effect of motor level was analyzed quantitatively by pooling responses across all questions (except those conditional on employment status to which not all participants responded) and participants within a motor-level group, and constructing frequency distributions for each response level (fig 4). The responses for the C4/C5 group were distributed lower and more widely than those of each of the other groups, reflected in a lower median (“neutral” versus “agree” to “strongly agree” for the other groups) and negligible skew (0.0 vs - 1.1 to -0.6). The latter statistic shows that responses were evenly distributed about the median for the C4lC5 group, but were concentrated around positive responses for the other groups. Overall, the distribution of responses for C4/C5-level participants was different from all other groups, individually or combined (x2 > 95, v = 3, p < .OOOl; in all cases) (fig 4). Even though the responses of the C4K5 group were relatively low, over half of the negative responses were reported by a 7-day-per-week user. Also, the omnibus statement “I would have the neuroprosthesis implanted again” prompted 3 “strongly agree” and 1 “agree” responses.
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Strongly Disagree & Disagree
i
t-1=600
Strongly Agree
C4K5
(n= 100)
C5/C5
(n=200)
t
t
I
E/C6
(n=ZOO)
Strongly Disagree & Disagree
Neutral
I
”
Agree
Strongly Agree
Score Fig 4. Distribution of Likert-scale responses, ie, the percentage of questions receiving each score, (A) pooled across all participants and (B) pooled across participants within each motor level. The total number of responses (20 per participant) included in each level is indicated in the graphs. Note that the “disagree” and “strongly disagree” responses were pooled because only one subject, a member of the C4/C5 group, responded with the latter.
Hand Impairment All participants improved in lateral and palmar pinch strength (lateral: median increase of llN, range of 4 to 31N; palmar: median increase of 5N, range of 0.3 to 17N), as shown in figure 5. All participants but one could complete more of the 6 tasks in the grasp-releasetest (median increase of 3 tasks,range of 0 to 5 tasks; fig 5), but the exploratory analyses suggested that those participants who could complete all 6 grasp-release tasks with the neuroprosthesis (n = 19) tended to have higher usage rates (median of 7 days donned per week, range of 0 to 7 days) than those who could not complete all the tasks (IZ= 15; median of 3 days, range of 0 to 7 days). Arch
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6
00 AEi! without with
Lateral
Ok-----
wlthout with
Palmar
Fig 5. Participants’ lateral and palmar pinch strength and number of tasks completed in a grasp and release test. The heavy line is the median, and the box represents the 25th to 75th percentiles. The 10th and 90th percentiles are represented by the whiskers. Small points are outliers.
DISCUSSION The primary purpose of this study was to assesssatisfaction with, impact of, and usage of a hand neuroprosthesis using a custom survey of 34 participants. The results were very positive overall, and showed the following: (1) the neuroprosthesis was used frequently-7 1% of the participants donned the neuroprosthesis 4 or more days per week and 85% of the participants used the device to some extent; (2) 87% of the participants also were generally satisfied with the neuroprosthesis; (3) 88% reported a positive impact on their life; (4) 87% experienced improved performance of ADL; and (5) 8 1% had improved independence. The high-levels of satisfaction and usage indicate that the neuroprosthesis meets at least some of the needs of most of the study participants. As found for rehabilitation technology in generals that successcan be correlated, in part, with the basic effectiveness of the neuroprosthesis. For example, participants who did not perform optimally on the grasp-release test, regardless of their motor level, reported lower usage rates. Usage rates varied widely, but 19 participants could complete all 6 tasks of the grasp-release test and most (17) used the device frequently (4 or more days per week). In contrast, only 7 of the 1.5participants who could not complete the grasp-release test used the neuroprosthesis as often. These results corroborate the importance of device effectiveness, but also confirm the utility of the grasp-releasetest as a clinical implementation tool. The test was designed (in part) as a quality-assurance indicator,6 where successful completion of all 6 tasks with the neuroprosthesis qualified the participant for discharge. Failure on any task, in contrast, would show that additional intervention (training, reprogramming, conditioning, etc) was warranted. Effectiveness is a necessary but not a sufficient condition for a satisfactory device. We note that one of the nonusers was also able to complete the 6 grasp-release tasks, but abandoned the neuroprosthesis because of skin irritation (from tape used to Arch
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aftix the transmitting coil) and the need for additional surgery. Participants desired several improvements in the device, including better dependability, smaller and lighter external components, easier donning, and fewer cables. These recommendations closely parallel the key characteristics identified in previous studies of assistive technology*,20 and are being addressed in a more recent version of the neuroprosthesis that incorporates an implanted angle sensor for generating command signals32,33and a compact external control unit. It may be unrealistic, however, to expect uniformly high rates of use even with these improvements. Some participants may always use the neuroprosthesis for specific activities performed intermittently, as found previously for functional orthoses.‘* The secondary purpose of the survey was to identify characteristics of participants who become successful, frequent users. Our analyses were largely exploratory, however, given the small study population and the large number of potential characteristics. The analysis of participants’ characteristics, such as their gender, pinch strength, or age at injury or implant surgery, suggests that motor level is most likely to affect outcome. The three strongest groups (C5K5 through C6K6) responded very positively to most of the statements (fig 4B) and the C5K.6 group showed the highest level of use (fig 3). The weakest participants (C4K5 motor level), in contrast, were more likely to give a neutral or negative response, especially to statements regarding occupation or independence. These 5 participants (out of 30 who completed the survey) accounted for 27 of the 31 negative responses (“disagree” or “strongly disagree”). The median response of this group was neutral, and these participants reported the lowest median usage rate (3 days per week). The equivocal outcome may result from deficiencies in the neuroprosthesis (eg, the C4K5 participants tended to have weaker stimulated grasps and none of them could complete all 6 tasks of the grasp-releasetest), proximal weakness in the implanted limb, or weakness of the contralateral C4 limb. It is also possible that the survey statements did not capture benefits apparently provided to this group, because half of the C4/C5 participants did use the device regularly (fig 5) and 4 of 5 would have the device implanted again. The results suggest that the C4/C5 group should not be excluded from further implementations of the neuroprosthesis, but they certainly warrant more extensive study and evaluation. A review of the reasons reported for not donning the system can be used to refine our original candidate selection criteria, to make suggestions for modifying the neuroprosthesis, and may help reduce non-use in the future. Like Scherer23and Vash,22we believe that candidates must be motivated, have optimistic and realistic goals, and have adequate attendant support. To date we rely on clinical judgement to determine if a candidate satisfies these requirements. In retrospect, however, 4 of the 5 nonusers may not have met these criteria, so stricter adherence or more formal assessmentmay reduce non-use. Other precautions for avoiding non-use may include applying a sham device to detect hypersensitivity to tape products prior to implantation, or early shoulder-strengthening exercises to determine if a participant will be able to use his or her shoulder without pain. As the technology and implementation are refined, the need for revision surgery may also decrease, and making the suggested improvements in the neuroprosthesis should increase effectiveness and decreasenonuse. In sum, the satisfaction survey showed that the participants were generally very satisfied with the neuroprosthesis, that they used it regularly and benefited from it. The benefits provided by the neuroprosthesis did vary across participants, and not all participants experienced the same changes in performance. We have not attempted to determine the relative weight that each
HAND
NEUROPROSTHESIS:
SATISFACTION
participant assigned to each benefit or inconvenience to construct a model of satisfaction and usage. However, since 29 out of 34 participants (85%) used the neuroprosthesis to some extent and 87% would have the surgery again (including 4 of the 5 participants in the C4/C5 group), we infer that the benefits derived must be greater than the inconveniences encountered. Improvements in the device,32,33 such as additional stimulus channels, an implanted command source, and a smaller, lighter external control unit, should make the neuroprosthesis easier to don, improve hand and arm function, and make the device operable if the user is confined to bed. Such changes are expected to make the current high level of satisfaction and use even better. Acknowledgments: The authors thank Ronald L. Hart, MS, and Gregory G. Naples, MS, of the Cleveland VA Medical Center and MetroHealth Medical Center, Cleveland, OH, for technical assistance; Nell Sedransk, PhD, and Scott A. Snyder, MS, Department of Statistics, Case Western Reserve University, Cleveland, OH, for help with statistics; and the following clinical trial investigators: M.J. Mulcahey, OT, Brian T. Smith, and Randall R. Betz, MD, of Shriner’s Hospital fir Children. Philadeluhia. PA (grant 9530): Janet Weis. OT. Vincent R. Hentz, MD, Amy i. Ladd, GE, and InderPerkash, MD of the Palo Alto VA Medical Center, Palo Alto, CA; Terry Retman, OT, Mark J. Koris, MD, and Allen W. Wiegner, PhD, of the West Roxbury VA Medical Center. West Roxburv. MA: Daniel P. Greenwald, Araceli Denoea. Audrey Nelson and ‘&&a Kunins of the Tampa VA Medical Center Hospital, Tampa, FL; Peter H. Gorman, MD, W. Andrew Eglseder Jr., MD, Linda Marshall, OT, and Mike Mahar of the Baltimore VA Medical Center, Baltimore, MD; Sara Carroll, Cathy Cooper, Gerard W. Sormann, MD, and Douglas J. Brown, MD, of the University of Austin Hospital in Melbourne, Australia; Paul Taylor, Julie Esnouf, and John A.E. Hobby, MD, of Salisbwy District Hospital of Salisbury, United Kingdom. 1.
2. 3.
4. 5. 6.
10.
11.
References Hanson RW, Franklin MR. Sexual loss in relation to other functional losses for spinal cord injured males. Arch Phys Med Rehabil 1976;57:291-3. Keith MW, Peckham PH, Thrope GB, Buckett JR, Stroh KC, Menger V. Functional neuromuscular stimulation neuroprostheses for the tetraplegic hand. Clin Orthop 1988;233:25-33. Smith B, Peckham PH, Keith MW, Roscoe DD. An externally powered, multichannel, implantable stimulator for versatile control of paralyzed muscle. IEEE Trans Biomed Eng 1987;34:499508. Peckham PH, Keith MW, Freehafer AA. Restoration of functional control by electrical stimulation in the upper extremity of the quadriplegic patient. J Bone Joint Surg Am 1988;70:144-8. Kilgore KL, Peckham PH, Keith MW, Thrope GB, Wuolle KS, Bryden AM, et al. An implanted upper-extremity neuroprosthesis: follow-up of five patients. J Bone Joint Surg Am 1997;79:533-41. Wuolle KS: Van Doren CL, Thrope GB, Keith MW, Peckham PH. Development of a quantitative hand grasp and release test for patients with tetraplegia using a hand neuroprosthesis. J Hand Surg [Am] 1994;19:209-18. Wijman CA, Stroh KC, Van Doren CL, Thrope GB, Peckham PH, Keith MW. Functional evaluation of quadriplegic participants using a hand neurourosthesis. Arch Phvs Med Rehabil 1990:71: 1053-7. Batavia AI, Hammer GS. Toward the development of consumerbased criteria for the evaluation of assistive devices. J Rehabil Res Dev 1990;27:425-36. Phillips B, Zhao H. Predictors of assistive technology abandonment. Assist Technol 1993;5:36-45. Kaolan LI. Grvnbaum BB. Rusk HA. Anastasia T. Gassler S. A reabpraisai of &aces and &her mechanical aids in patients with spinal cord dysfunction: results of a follow-up study. Arch Phys Med Rehabil 1966;47:393-405. Bynum HS, Rogers JC. The use and effectiveness of assistive devices possessed by patients seen in home care. Occup Ther J Res 1987:7:181-91.
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12. Scherer MJ, Mckee BG. But will the assistive technology be used? In: Presperin JJ, editor. Technology for the next decade. Proceedings of the 12thAnnual RESNAConference; 1989 June 25-30; Los Angeles. Washington (DC): RESNAPress; 1989, p. 356-7. 13. Garber SL, Gregorio TL. Upper extremity assistive devices: assessment of use by spinal cord-injured patients with quadriplegia. Am J Occup Ther 1990;44: 126-3 1. 14. Mann, WC, Hun-en D, Tomita M. Comparison of assistive technology use and needs of home-based older persons with different impairments. Am J Occup Ther 1993;47:980-7. 15. Allen VR. Follow-up study of wrist-driven flexor hinge-splint use. Am J Occup Ther 1971;25:420-2. 16. Spieker JL, Lethcoe BJ. Upper extremity functional bracing: a follow-up study. Am J Occup Ther 1971;25:398-401. 17. Knox CC, Engel WH, Siebens AA. Results of a survey on the use of a wrist driven splint for prehension. Am J Occup Ther 1971;25:109-11. 18. Nichols PJ, Peach SL, Haworth RJ, Ennis J. The value of flexor hinge hand splints. Prosthet Orthot Int 1978;2:86-94. 19. Rogers JC, Figone JJ. Traumatic quadriplegia: follow-up study of self-care skills. Arch Phys Med Rehabil 1980;61:316-21. 20. Wise MF, Wharton GW, Robinson TD. Long term use of functional hand orthoses by quadriplegics. American Spinal Injury Association Bulletin 1986;14(2):4-5. 21. Silcox DH 3rd, Rooks MD, Vogel RR, Fleming LL. Myoelectric prostheses: a long-term follow-up and a study of the use of alternate prostheses. J Bone Joint Surg Am 1993;75:1781-9. 22. Vash CL. Psychological aspects of rehabilitation engineering. In: Redden MR, Stems VW, editors. Technology for independent living II. Issues in technology for daily living, education, and employment. Washington (DC): American Association for the Advancement of Science; 1983. p. 48-59. 23. Scherer M. Assistive device utilization and quality-of-life in adults with spinal cord injuries or cerebral palsy. J Appl Rehabil Couns 1988;19:21-30. 24. McDowell CL, Moberg EA, House JH. The Second International Conference on Surgical Rehabilitation of the Upper Limb in Tetraplegia (Quadriplegia). J Hand Surg [Am] 1986;11:604-8. 25. American Spinal Injury Association. International standards for neurological and functional classification of spinal cord injury, revised 1992. Atlanta (GA); American Spinal Injury Association; 1992. 26. Kelly CM, Freehafer AA, Peckham PH, Stroh K. Postoperative results of opponensplasty and flexor tendon transfer in patients with spinal cord injuries. J Hand Surg [Am] 1985;10:890-4. 21. Keith MW, Lacey SH. Surgical rehabilitation of the tetraplegic upper extremity. J Neurol Rehabil 1991;5:75-87. 28. Hentz VR, House J, McDowell C, Moberg E. Rehabilitation and surgical reconstruction of the upper limb in tetraplegia: an update. J Hand Surg [Am] 1993;17:964-7. 29. House JH, Gwathmey FW, Lundgaard DK. Restoration of strong grasp and lateral pinch in tetraplegia due to cervical spinal cord injury. J Hand Surg [Am] 1976;1:152-9. 30. Hentz VR, Ladd AL, Perkash I. A complication of the implantable functional neuromuscular stimulation system-case report [abstract]. In: Proceedings of the Vth International Congress on Surgical Rehabilitation of the Upper Limb in Tetraplegia (Quadriolegiak 1995 March 26-29: Melbourne. Australia. Melbourne: V*th &t&national Congress; 1985. ’ 31. Breiman L, Friedman JH, Olshen RA, Stone CJ. Classification and regression trees. Monterey (CA): Wadsworth and Brooks/Cole; 1984. 32. Smith B, Tang Z, Johnson MW, Pourmehdi S, Gazdik MM, Buckett JR, et al. An externally powered, multichannel, implantable stimulator-telemeter for control of paralyzed muscle. -IEEE Tram Biomed Ene 1998:45:463-75. 33. Kilgore KL, Pecl&am PH, Keith MW, Bhadra N, Bryden AM. A second-generation implanted upper extremity neuroprosthesis [abstract]. In: Proceedings of the American Spinal Injury Association, 1998April15-19; Cleveland (OH). Atlanta (GA): American Spinal Injury Association; 1998. p. 42. Supplier a. FreeHanda; NeuroControl Corporation, Cleveland, OH. Arch
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Satisfaction With and Usage of a Hand Neuroprosthesis Kathryn Stroh Wuolle, OTR/L, CHT, Clayton L. Van Doren, PhD, Anne M. Bryden, OTRIL, R Hunter Peckham, PhD, Michael W Keith, MD, Kevin L. Kilgore, PhD, Julie H. Grill, MS ABSTRACT. Stroh Wuolle K, Van Doren CL, Bryden AM, Peckman PH, Keith MW, Kilgore KL, Grill JH. Satisfaction with and usage of a hand neuroprosthesis. Arch Phys Med Rehabil 1999;80:206-13. Objective: To measure the satisfaction with, clinical impact of, and use of an implantable hand neuroprosthesis. Setting: Eight different medical centers. Participants: Thirty-four individuals with spinal cord injuries at the C5 or C6 motor level. Interventions: Participants were implemented with a hand neuroprosthesis that provides grasp and release. The neuroprosthesis includes a surgically implanted stimulator, implanted electrodes sutured to the hand and forearm muscles, and an externally mounted controller. Main Outcome Measure: A survey was mailed to study participants, who were asked to respond to statements such as “If I had it to do over, I would have the hand system implanted again,” using a 5-level Likert scale (“strongly agree” to “strongly disagree”). Results: Eighty-seven percent of participants were very satisfied with the neuroprosthesis, 88% reported a positive impact on their life, 87% reported improvements in activities of daily living, and 81% reported improved independence. Participants reported using the neuroprosthesis a median of 5.5 days per week; 15 participants used the neuroprosthesis 7 days per week, and 5 participants reported not using the device. Conclusions: The neuroprosthesis was used by most participants. The neuroprosthesis performed satisfactorily, increased users’ ability to perform activities of daily living and independence, and improved their quality of life. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation
P
ROVIDING INCREASED hand function for individuals with tetraplegia is an important rehabilitation objective. Hanson and Franklin1 asked a group of tetraplegic men to rank-order functional losses associated with their injury, and 76% of the men ranked the loss of arm and hand function
From the Functional Electrical Stimulation Center, MetroHealth Medical Center (Ms. Stroh Wuolle, Drs. Peckham, Keith, Kilgore); the Cleveland VA Medical Center (Ms. Stroh Wuolle, Ms. Bryden, Drs. Peckham, Keith, Kilgore); the Department of Orthopaedics and Biomedical Engineering, Case Western Reserve University (Drs. Van Dorm, Peckham, Keith, Kilgore); and NeuroControl Corporation (Ms. Grill), Cleveland, OH. Submitted for publication October 29, 1997. Accepted in revised form July 24, 1998. Supported in part by the Rehabilitation Research and Development Service of the Department of Veterans Affairs (Merit Review BOl l-6RA) and the National Institotes of General Health Clinical Research Center at MetroHealth Medical Center (MOlRR00080). A commercial party having a direct financial interest in the results of the research supporting this article has conferred or will confer a benefit upon one or more of the authors. Reprint requests to Laura Polacek, MetroHealth Medical Center, H601, 2500 MetroHealth Drive, Cleveland, OH 44109-1998. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003.9993/99/X002-4702$3.00/0
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highest-above the loss of leg, bladder and bowel, or sexual function. The latter were ranked highest by only X.1%, 13.5%, and 2.7% of the study group, respectively. A neuroprosthesis” has been developed that provides lateral and palmar grasp to persons with C5 and C6 motor level spinal cord injuries. The neuroprosthesis consists of both implanted and external components (fig 1). The receiver-stimulator is surgically implanted on the participant’s chest, in a location similar to placement of a pacemaker. Eight electrodes are passed subcutaneously from the receiver-stimulator down the arm and sutured to muscles in the forearm and hand (generally the extensor digitorum communis, extensor pollicis longus, abductor pollicis brevis, adductor pollicis, flexor pollicis longus, flexor digitorum superficialis, flexor digitorum profundus). Hand opening and closing are controlled through voluntary motion of the opposite shoulder. As individuals elevate and depress the shoulder, the motion is detected by a shoulder-position sensor mounted on the chest. This signal is transmitted to an external microprocessor unit that sends stimulus control signals to the implanted receiverstimulator (via radio frequency transmission). In turn, the implant receiver-stimulator generates the appropriate pattern of electrical pulses to open and close the hand.2-4 The efficacy of the neuroprosthesis has been measured in several ways, including pinch strength, range of motion, ability to grasp and release, and performance of activities of daily living.5-7 Batavia and Hammer8 however, state that the most important basis for evaluating an assistive device is whether it meets the needs of the disabled consumer. Several authors studied the relationship of device characteristics to consumer preference and found four important criteria for success: (1) effectiveness: how well the device enhances the users functional capability; (2) affordability: how much it costs to purchase, maintain, and repair the device; (3) operability: how easy the device is to operate; and (4) dependability: how long the device operates without reduced performance or breakdown. Additional criteria include, ranked in order of importance, portability, durability, compatibility, flexibility, ease of maintenance, securability, learnability, personal acceptance, physical comfort, supplier repair, physical security, consumer repair, and ease of assembly.8 Phillips and Zhao9 found four factors that were significantly related to abandoning the device: change in user needs or priorities (including improvement in functional abilities and change in personal activities or goals), easeof obtaining the device (the easier a device is to obtain, the more likely it is to be abandoned), poor device performance (including inadequate effectiveness, reliability, durability, comfort, safety, and ease of use), and lack of consideration of user opinion in selection. Phillips and Zhaog also found that most abandonment occurs within the first year or after 5 years of use. Phillips and Zhao9 and Batavia and Hammers emphasized the importance of soliciting consumer involvement and understanding the long-term needs of consumers in reducing abandonment and enhancing consumer satisfaction. Failure to do so often leads to abandonment of the technology, as reported by many authors.8,10-14According to Scherer and McKee,‘* rates of abandonment have been reported from as low as 8% to as high as 75%, with 30% being average. Studies of satisfaction with and use of conventional devices
HAND
NEUROPROSTHESIS:
SATISFACTION
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USE,
Implanted Components
Stroh
207
Wuolle
External Components
Receiver Stimulator
External Control Unit
Fig 1. The neuroprosthesis consists internal components (receiver-stimulator,
of external components (external 8 epimysial electrodes).
for upper-extremity rehabilitation highlight more specific requirements for successful deployment. Follow-up studies of functional orthosis use by individuals with tetraplegia, for example, indicate usage rates that range from 39% to 89%,9,15-2o although usage was not measured consistently in these studies. Functional splints are generally useful for eating with utensils, writing, grasping objects, using a telephone, and typing.17 Nichols and colleagues18however, found that some individuals wear the splints only to perform specific activities. Wise and colleagues20believe that continued use of an orthosis is due to early intervention (within 2 weeks of admission) and extensive training (at least 4 months of inpatient training). In their study, outpatients showed the lowest acceptance rates, and only 20% continued to use the devices prescribed. Individuals also would not use the orthosis if their functional ability had increased or decreased, or if the orthosis fit poorly, weighed too much, interfered with wheelchair propulsion, was difficult to don and doff, or was unreliable: unattractive or too expensive.15J6J8 Prostheses used after amputations have had similar abandonment problems. Silcox and colleagues21found a 50% rejection rate of a myoelectric prosthesis and a 32% rejection rate for a conventional prosthesis. Reasons for rejection included the excessive weight of the prosthesis, its sluggish responsiveness, its poor durability and fit, and difficulty in operating it. Other authors have explored the relationship between technology acceptance and personal characteristics.22s23Disability acceptance, motivation, goal-directedness, perceived life tasks, effort-reward balance, and life satisfaction are all related to positive attitudes toward devices. Scherer23 also found that assistive devices are used more often and successfully the longer the person has to adjust to their spinal cord injury (SCI), the younger the person is at injury, and the higher the degree of malleabihty. As with any new technology, it is imperative that user satisfaction and rates of usage be assessedearly in the clinical deployment of the neuroprosthesis. Such assessmentwill make
control
unit,
shoulder
position
transducer)
and
surgically
implanted
possible improvement of the device based on consumer input, and help to refine the criteria used to select the most appropriate potential users. Because authors of each of the referenced studies designed their own evaluation tools and did not incorporate formal follow-up protocols, there was no standard or accepted evaluation tool for use in our follow-up with the neuroprosthesis recipients. Therefore, we designed a custom survey to measure whether the neuroprosthesis was actually used in everyday life, to measure whether participants were satisfied with the device, to determine the impact of the neuroprosthesis on participants’ lives, to determine the change in activities of daily living (ADL), independence, and occupation, and to record participants’ comments and suggestions. METHODS All of the procedures were approved by the institutional review boards of the participating institutions. Subjects Candidates for the hand grasp neuroprosthesis included individuals with the following characteristics: (1) an international classification in group 0, 1, or 2, (ocular [0] or cutaneous [C] afferent inputs% as described in table 1, and an American Spinal Injury Association (ASIA) C.5 or C6 motor leveLz5 (2) neurologically stable, (3) skeletally mature, (4) at least 12 months after injury, (5) good passive range of motion of the upper extremity, (6) sufficient shoulder and elbow strength, along with adequate postural support to position the hand functionally once implemented with a hand neuroprosthesis, (7) strong, electrically excitable hand flexion and extension muscles or a muscle that could be transferred to substitute for a weak stimulated response, (8) an adequate attendant support system to assist with follow-up, (9) independent wheelchair mobility, (10) good general health, (11) an optimistic and motivated state of mind, with realistic goals and an adequate adjustment to their Arch
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HAND
Table
1: International Classification in Individuals With
Sensibility*
“0”
Group
or “Cu”
0
1 2
or “Cu” or “Cu”
for Surgery Tetraplegia
No muscle
Elbow for
transfer Brachioradialis Extensor carpi radialis
flexion
forearm
and
supina-
tion Wrist
extension extension
longus
“0”
or “Cu”
3
Extensor radialis
carpi brevis
Wrist
“0”
or “Cu”
4
Pronator
teres
Wrist extension pronation
“0”
or “Cu”
“0”
or “Cu”
5 6
Flexor Finger
“0”
or “Cu”
7
Thumb
“0”
or “Cu”
8
Partial digital flexors
“0”
or “Cu”
9
Lacks
“0”
or “Cu”
X
Exceptions
carpi radialis extensors
and
Wrist flexion Extrinsic finger extension
extensors
only
Extrinsic thumb extension
intrinsics
Extrinsic flexion
finger (weak)
Extrinsic flexion
finger
* “0” or “Cu” refers to ocular afferent input or cutaneous afferent input (ie, IOmm Z-point discrimination threshold on thumb and index finger). + Motor description assumes that all listed muscles are grade 4 (Medical Research Council) or better, and each group has listed muscle plus muscles of all weaker groups.
disability. Participants who were international classification group 3 (ie, grade 4 extensor carpi radialis longus and extensor carpi radialis brevis) were not enrolled routinely, and were given the option of tendon transfer surgery for improved hand function or a neuroprosthesis.26-29Some of these characteristics (eg, optimism and motivation) were not assessedformally. Forty-two participants had been implemented with the neuroprosthesis at eight clinical institutions worldwide at the time the survey was performed. (As of this writing, there are 104 neuroprosthesis recipients worldwide.) Six participants were too early in their postsurgical rehabilitation to be included in the study. One participant died for reasons unrelated to the implant, and another had the implant removed secondary to an infection from a pressure sore.3oBoth of these participants had used the neuroprosthesis regularly but are not included in this study. The remaining 34 participants who were assessedhad completed their rehabilitation training in use of the neuroprosthesis and were at least 1 year after surgery, including at least 6 months of home use. Six participants were motor level C4K.5 (C4 one arm, C5 the other), 12 were CYC5, 10 were C5K6, and 6 were C6/C6. Table 2 presents ASIA motor levels and international classifications by arm. Eight women and 26 men participated, ranging in age at injury from 13 to 53 years old (median, 25 years) and in age at implantation from 16 to 57 years (median, 30 years). The time between injury and implantation ranged from 14 months to more than 32 years (median, 4 years), and the time between the implant and the survey ranged from 14 months to 9 years (median, 5.2 years). Thirty-one participants had adjunctive surgeries on their upper extremities such as a tendon transfer (30 had surgery on their neuroprosthesis arm and 15 on the other arm). Impairment Measures All participants completed functional evaluations (a standardized test of grasp and release6 and measurements of pinch Arch
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strength and range of motion) at several time points as part of the clinical trial5 but data reported here were collected from the rehabilitation and training period following implantation of the neuroprosthesis or the l-year postimplantation follow-up.
Function
below suitable
SATISFACTION
of the Hand
Characteristics
elbow “0” “0”
NEUROPROSTHESIS:
Satisfaction Survey The main objective of this study was to measure the impact of, satisfaction with, and use of a hand neuroprosthesis as perceived by participants. The survey was initially designed by the authors, applied in a pilot study, and subsequently modified by the authors and investigators from the manufacturer of the neuroprosthesis,a who sponsored its FDA-monitored clinical trials. Participants received the survey by mail and an independent market research firm, under contract, retrieved the answers from the participants by telephone. In Part 1 of the survey, participants were asked to respond to statements such as “If I had it to do over, I would have the hand system implanted again,” using a 5-level Likert scale (strongly disagree, disagree, neutral, agree, or strongly agree). Figure 2 lists an abbreviated version of each of the statements used in the survey (six statements on general satisfaction; four on life impact; six on ability to perform activities; five on independence; three on impact on work, school, home maintenance, and childcare; and one on appearance). The remaining questions (Part 2) asked participants to: report on average how many days a week they used the device; list the activities for which they used their neuroprosthesis; comment on any negative responses to the statements in Part 1; cite any reasons for not using the neuroprosthesis; estimate the amount of attendant care time needed before and after the implant; and to make any general comments or criticisms. Three participants refused to complete the survey, and one participant was not administered the survey because the participant lived in Croatia. For completeness, though, the first author telephoned these four participants to determine their frequency of use and their reasons for not donning the system. The partial data are used in the summaries of usage statistics and participant characteristics and in hand impairment comparisons to provide a more complete picture of all the participants and to try to ensure that those refusing to be surveyed were represented. Data Analysis Analyses were primarily descriptive because the study population was small and the survey has not been validated formally. Classification and regression trees31(S-plus, version 4.0) were used to explore associations between each of the Likert scale responses or the frequency of use and 13 predictor variables, including demographic variables (gender, age at implant and injury, time between implant and surgery, motor level) and measures of impairment (lateral, palmar, and five-finger grasp Table
2: Number
Classification
ASIA
motor
of Arms
Classification
Group
NP Arm
c4 c5 C6
0 19 15
21 7
0 1 2
6 15 12
11 16 6
3
1
1
23 11
27 7
level
International
Sensation
Abbreviation:
in Each
0 cu NP, neuroprosthesis.
Other
Arm
6
HAND
Category:
NEUROPROSTHESIS:
SATISFACTION
AND
USE,
Stroh
Wuolle
% Responses:
Questions:
General Satisfaction
I wouldrecommendthe NPto otherswith SC1 I am satisfiedwith my NP The NP is reliable I wouldhavethe NP implantedagain TheNP hasmet my expectations I would pay for the NP if I had the money Life Impact (TheNP hasnegativelyimpactedmy life) TheNP hasimprovedmy qualityof life The NPhaspositivelyimpactedmy life I havebenefitedfrom the NP ADL are easierto perform ADL I canperformmoreADL I feel moreconfidentperformingADL I performADL more“normally” I performADL faster Independence I am ableto function moreindependently I requirelessassistance from others I uselessadaptiveequipment I am more comfortableout in the community Occupation Positiveimpacton workischoolperformance Positiveimpacton potentialto work/school Positiveimpacton homemaintenance/child care Appearance The appearanceof my handhasimproved Key: Fig 2. Percentage of participants disagree” as per key). Questions life impact” have been inverted
responding to questions are listed in abbreviated for consistency with the
n
strongly agree
neutral
0
disagree
in Pat-t 1 of the satisfaction survey at each of 5 levels (“strongly form and were not presented in the order shown. The responses rest of the questions. NP, neuroprosthesis.
forces; grasp-release test performance) with and without the neuroprosthesis. Ordinary regressions (Microsoft Excel version 6.0) were also performed between each of the outcome variables and each of the predictor variables. These analyses suggested that motor level had the most robust overall effect on the Likert responses and usage. Differences among the motor levels for the Likert responses were analyzed simply using contingency tables and x2 tests. Usage was not analyzed similarly since the number of responses in each category was small (0 to 4, typically). RESULTS Part 1 Participants responded very positively. The Likert scale responses to the statements in Part 1 are presented in figure 2 (see also fig 4A). The statements are grouped into six areas: general satisfaction, life impact, ADL, independence, occupation, and appearance. Responses within each group were pooled to calculate overall percentages. General satisfaction. Participants were very satisfied with the neuroprosthesis, in general; 87% of the responses in this group of questions were positive (“agree” or “strongly agree”). All but one of the participants (97%) would recommend the neuroprosthesis to others, 90% were satisfied with the neuroprosthesis, 90% stated the neuroprosthesis was reliable, 87% would have the surgery again, 80% felt the neuroprosthesis met their expectations, and 77% would pay for the neuroprosthesis if they had the money. Life impact. Eighty-eight percent of the responses were positive for life impact. Participants stated that the neuroprosthesis improved their quality of life (90%), made a positive impact
q
strongly disagree
agree” to “strongly regarding “negative
on their life (87%) (did not make a negative impact, 90%), and provided a benefit (83%). ADL. Eighty-seven percent of the responses regarding changes in ADL were positive. Ninety-three percent of participants could perform ADL easier, 93% could perform more ADL such as painting and shaving, 90% had increased confidence when performing ADL, 83% could perform ADL more “normally,” and 73% could perform ADL faster. Independence. Overall, 81% of the responses to the independence statements were positive. Eighty-seven percent of the participants reported that they were able to function more independently, 83% used less adaptive equipment, 87% required less assistancefrom others, and 67% felt more comfortable out in the community alone. Participants were also asked to estimate (in hours) the attendant time required daily before and after receiving the neuroprosthesis, a somewhat more objective measure than the Likert responses. The difference in attendant time (ie, time required with the neuroprosthesis minus the time required without the neuroprosthesis) varied widely by participant, with a median of 0 hours per day (ranging from a decrease of 11 attendant hours per day to an increase of 1 hour). Nineteen participants stated that the neuroprosthesis did not change the actual hours of attendant time, even though 16 of these participants felt they were able to function more independently. This could indicate that participants considered other factors when asked about independence, or that participants only thought about their morning and evening attendant, who usually still came to assistthem even after they received the neuroprosthesis, or that their attendant came the same number of hours but performed different activities. Occupation. Figure 2 reports the percentage of positive “occupation” responses (74%) for only those participants who Arch
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worked at the time of the survey (or went to school, II = 13) and those who intended to work (or intended to go to school, n = 9). There was a large number of neutral responses for impact on home maintenance and child care, with only 34% positive responses. Overall, 57% of participants’ responses to occupation questions were positive. Appearance. The appearance of the participants’ hands were not expected to change much. Overall, 87% of the participants felt their hand appearance was unchanged or improved. Part 2 The second part of the survey asked questions regarding frequency of device use and the activities for which the device was used, and solicited comments regarding changes in quality of life, suggestions for improvements, reasons for not donning the neuroprosthesis, and general comments. All 34 participants were queried regarding frequency of use and reasonsfor nonuse. Not all participants cited activities or provided comments, Usage. Average usage is plotted in figure 3 for all 34 participants combined and for each motor level. Participants reported using the neuroprosthesis a median of 5.5 days per week, but ranged from 15 participants (44%) who donned the neuroprosthesis 7 days per week to 5 participants (15%) who donned the neuroprosthesis less than 1 day per week. Twentyfour of 34 participants (71%) reported using their neuroprosthesis 4 or more days per week. The range of usage for C4K5, C5/C5, and C6K6 levels was the same, (0 to 7 days per week), whereas the C5lC6 group used the neuroprosthesis most regularly (4 to 7 days per week), with most participants (800) reporting daily use. Activities. Participants were asked to list activities for which they used their neuroprosthesis. The activities reported varied across participants. The most frequently reported activities included eating, drinking, shaving, brushing teeth, brushing hair, writing, operating a computer, and playing games. Other mentioned activities included preparing food, using a corkscrew, shopping, applying make-up, face-washing, typing, using a telephone, filing, picking up books, turning pages, using computer disks, paying bills, using a fax machine, increasing work area, reaching into drawers, using remote controls, playing audio cassettes, using video tapes, using power machines, painting, sketching, building models, smoking, opening doors, assisting children with homework, and picking up miscellaneous items. Quality of life comments. Eighteen participants made positive comments about how their quality of life changed, one participant responded neutrally (no change in quality of life) and one responded negatively. All positive comments were related to the effectiveness of the device and included reports of: increased independence (12 responses), increased ability to do ADL (10 responses), increased confidence and self esteem (5 responses), ability to perform activities more “normally” (3 responses), increased ease in performing tasks (2 responses), and decreased use of adaptive equipment (1 response). The one negative comment about quality of life regarded lack of effectiveness (still needing help for most activities) and difficulty with maintenance in that the participant required additional assistanceto don the neuroprosthesis. Suggested improvements. The improvements participants stated they wanted to see in the neuroprosthesis included increasing dependability (8 responses), making the external devices smaller and lighter (6 responses),making the neuroprosthesis easier to don (6 responses), reducing the number of cables (5 responses), making more of the components implantable (2 responses), making the movement more precise (2 Arch
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Days Donned Fig 3. Distribution of usage rates, ie, the percentage of participants reporting each rate, (A) pooled across all participants and (B) pooled across participants within each motor level. The number of participants included in each level is indicated in the graphs.
responses), including more muscles for triceps and bilateral systems (2 responses), and making it easier to control (1 response). Reasons for not donning. Participants were asked why they did not use the neuroprosthesis if they did not. After stating the reason(s), participants were asked to rank their reasons for not donning the device from the most frequent (rank 1) to the least frequent. Twelve participants stated “not applicable” since they used the system every day. The remaining 22 participants’ responses were separated into nonusers (5) and users (17) so that we can pay special attention to those individuals who have abandoned the technology. The median rank participants assigned to each reason and the median days donned per week across those who gave that reason are presented to estimate an approximate importance of each
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reason. A reason given by a 6-day-per-week user is probably less important overall than one cited by a l-day-per-week user. There were three reasons nonusers gave that were unique: (1) revision surgery was needed (2 nonusers, median rank = 1.5) (2) the neuroprosthesis hand was contracted and no longer worked (1 nonuser, rank 1; the patient stated that this occurred because he did not use splints or complete range of motion exercises), and (3) for the same C4K5 individual, his shoulder became painful upon using his arm for activities (1 nonuser, rank 2). The other reasons nonusers gave were similar to, but stronger than, reasons cited by users. For example, one nonuser said he was depressed about life and was not getting out of bed, while a user said that he had low demands because of lifestyle. Both statements reflect problematic motivation, but the nonuser’s condition was more severe. The remaining reasons participants gave for not using the neuroprosthesis were: (1) their attendant did not have time (7 users, median rank = 2, median usage = 4), (2) they did not use their system when they were in bed because of illness, lack of an attendant, or just choosing to stay in bed on a given day (6 users, 1 nonuser, median rank = 1, median usage = 4), (3) the system was not needed or they could perform same activities without it (6 users, 1 nonuser, median rank = 2, median usage = 3), (4) they had skin irritations from the tape or transmitting coil (6 users, 1 nonuser, median rank = 2, median usage = 4), (4) they were not in the habit or mood (6 users, median rank = 2, median usage = 4), (6) the participant did not have time (5 users, median rank = 2, median usage = 5), (7) the system malfunctioned (3 users, median rank = 2, median usage = 5) (8) the appearance was an issue (3 users, median rank = 2, median usage = 6), (9) they had motivational problems, reporting depressed or low demands because of their lifestyle (1 user, 1 nonuser, rank = 1, median usage = 0.5), and (10) “other” (1 user, rank = 1, usage = 7). Comments. Participants were encouraged to share any comments or criticisms regarding the neuroprosthesis. Of 14 participants who responded, 12 responded positively, stating they were happy with the device and its effectiveness. One participant responded positively but also discussed improving dependability. Finally, one participant responded negatively stating the neuroprosthesis was costly and not effective. Participant characteristics. The exploratory analyses showed that, of all the personal characteristics, only motor level consistently accounted for differences in Likert-level responses to questions in Part 1 of the survey. The effect of motor level was analyzed quantitatively by pooling responses across all questions (except those conditional on employment status to which not all participants responded) and participants within a motor-level group, and constructing frequency distributions for each response level (fig 4). The responses for the C4/C5 group were distributed lower and more widely than those of each of the other groups, reflected in a lower median (“neutral” versus “agree” to “strongly agree” for the other groups) and negligible skew (0.0 vs - 1.1 to -0.6). The latter statistic shows that responses were evenly distributed about the median for the C4lC5 group, but were concentrated around positive responses for the other groups. Overall, the distribution of responses for C4/C5-level participants was different from all other groups, individually or combined (x2 > 95, v = 3, p < .OOOl; in all cases) (fig 4). Even though the responses of the C4K5 group were relatively low, over half of the negative responses were reported by a 7-day-per-week user. Also, the omnibus statement “I would have the neuroprosthesis implanted again” prompted 3 “strongly agree” and 1 “agree” responses.
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”
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Score Fig 4. Distribution of Likert-scale responses, ie, the percentage of questions receiving each score, (A) pooled across all participants and (B) pooled across participants within each motor level. The total number of responses (20 per participant) included in each level is indicated in the graphs. Note that the “disagree” and “strongly disagree” responses were pooled because only one subject, a member of the C4/C5 group, responded with the latter.
Hand Impairment All participants improved in lateral and palmar pinch strength (lateral: median increase of llN, range of 4 to 31N; palmar: median increase of 5N, range of 0.3 to 17N), as shown in figure 5. All participants but one could complete more of the 6 tasks in the grasp-releasetest (median increase of 3 tasks,range of 0 to 5 tasks; fig 5), but the exploratory analyses suggested that those participants who could complete all 6 grasp-release tasks with the neuroprosthesis (n = 19) tended to have higher usage rates (median of 7 days donned per week, range of 0 to 7 days) than those who could not complete all the tasks (IZ= 15; median of 3 days, range of 0 to 7 days). Arch
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00 AEi! without with
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Ok-----
wlthout with
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Fig 5. Participants’ lateral and palmar pinch strength and number of tasks completed in a grasp and release test. The heavy line is the median, and the box represents the 25th to 75th percentiles. The 10th and 90th percentiles are represented by the whiskers. Small points are outliers.
DISCUSSION The primary purpose of this study was to assesssatisfaction with, impact of, and usage of a hand neuroprosthesis using a custom survey of 34 participants. The results were very positive overall, and showed the following: (1) the neuroprosthesis was used frequently-7 1% of the participants donned the neuroprosthesis 4 or more days per week and 85% of the participants used the device to some extent; (2) 87% of the participants also were generally satisfied with the neuroprosthesis; (3) 88% reported a positive impact on their life; (4) 87% experienced improved performance of ADL; and (5) 8 1% had improved independence. The high-levels of satisfaction and usage indicate that the neuroprosthesis meets at least some of the needs of most of the study participants. As found for rehabilitation technology in generals that successcan be correlated, in part, with the basic effectiveness of the neuroprosthesis. For example, participants who did not perform optimally on the grasp-release test, regardless of their motor level, reported lower usage rates. Usage rates varied widely, but 19 participants could complete all 6 tasks of the grasp-release test and most (17) used the device frequently (4 or more days per week). In contrast, only 7 of the 1.5participants who could not complete the grasp-release test used the neuroprosthesis as often. These results corroborate the importance of device effectiveness, but also confirm the utility of the grasp-releasetest as a clinical implementation tool. The test was designed (in part) as a quality-assurance indicator,6 where successful completion of all 6 tasks with the neuroprosthesis qualified the participant for discharge. Failure on any task, in contrast, would show that additional intervention (training, reprogramming, conditioning, etc) was warranted. Effectiveness is a necessary but not a sufficient condition for a satisfactory device. We note that one of the nonusers was also able to complete the 6 grasp-release tasks, but abandoned the neuroprosthesis because of skin irritation (from tape used to Arch
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aftix the transmitting coil) and the need for additional surgery. Participants desired several improvements in the device, including better dependability, smaller and lighter external components, easier donning, and fewer cables. These recommendations closely parallel the key characteristics identified in previous studies of assistive technology*,20 and are being addressed in a more recent version of the neuroprosthesis that incorporates an implanted angle sensor for generating command signals32,33and a compact external control unit. It may be unrealistic, however, to expect uniformly high rates of use even with these improvements. Some participants may always use the neuroprosthesis for specific activities performed intermittently, as found previously for functional orthoses.‘* The secondary purpose of the survey was to identify characteristics of participants who become successful, frequent users. Our analyses were largely exploratory, however, given the small study population and the large number of potential characteristics. The analysis of participants’ characteristics, such as their gender, pinch strength, or age at injury or implant surgery, suggests that motor level is most likely to affect outcome. The three strongest groups (C5K5 through C6K6) responded very positively to most of the statements (fig 4B) and the C5K.6 group showed the highest level of use (fig 3). The weakest participants (C4K5 motor level), in contrast, were more likely to give a neutral or negative response, especially to statements regarding occupation or independence. These 5 participants (out of 30 who completed the survey) accounted for 27 of the 31 negative responses (“disagree” or “strongly disagree”). The median response of this group was neutral, and these participants reported the lowest median usage rate (3 days per week). The equivocal outcome may result from deficiencies in the neuroprosthesis (eg, the C4K5 participants tended to have weaker stimulated grasps and none of them could complete all 6 tasks of the grasp-releasetest), proximal weakness in the implanted limb, or weakness of the contralateral C4 limb. It is also possible that the survey statements did not capture benefits apparently provided to this group, because half of the C4/C5 participants did use the device regularly (fig 5) and 4 of 5 would have the device implanted again. The results suggest that the C4/C5 group should not be excluded from further implementations of the neuroprosthesis, but they certainly warrant more extensive study and evaluation. A review of the reasons reported for not donning the system can be used to refine our original candidate selection criteria, to make suggestions for modifying the neuroprosthesis, and may help reduce non-use in the future. Like Scherer23and Vash,22we believe that candidates must be motivated, have optimistic and realistic goals, and have adequate attendant support. To date we rely on clinical judgement to determine if a candidate satisfies these requirements. In retrospect, however, 4 of the 5 nonusers may not have met these criteria, so stricter adherence or more formal assessmentmay reduce non-use. Other precautions for avoiding non-use may include applying a sham device to detect hypersensitivity to tape products prior to implantation, or early shoulder-strengthening exercises to determine if a participant will be able to use his or her shoulder without pain. As the technology and implementation are refined, the need for revision surgery may also decrease, and making the suggested improvements in the neuroprosthesis should increase effectiveness and decreasenonuse. In sum, the satisfaction survey showed that the participants were generally very satisfied with the neuroprosthesis, that they used it regularly and benefited from it. The benefits provided by the neuroprosthesis did vary across participants, and not all participants experienced the same changes in performance. We have not attempted to determine the relative weight that each
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participant assigned to each benefit or inconvenience to construct a model of satisfaction and usage. However, since 29 out of 34 participants (85%) used the neuroprosthesis to some extent and 87% would have the surgery again (including 4 of the 5 participants in the C4/C5 group), we infer that the benefits derived must be greater than the inconveniences encountered. Improvements in the device,32,33 such as additional stimulus channels, an implanted command source, and a smaller, lighter external control unit, should make the neuroprosthesis easier to don, improve hand and arm function, and make the device operable if the user is confined to bed. Such changes are expected to make the current high level of satisfaction and use even better. Acknowledgments: The authors thank Ronald L. Hart, MS, and Gregory G. Naples, MS, of the Cleveland VA Medical Center and MetroHealth Medical Center, Cleveland, OH, for technical assistance; Nell Sedransk, PhD, and Scott A. Snyder, MS, Department of Statistics, Case Western Reserve University, Cleveland, OH, for help with statistics; and the following clinical trial investigators: M.J. Mulcahey, OT, Brian T. Smith, and Randall R. Betz, MD, of Shriner’s Hospital fir Children. Philadeluhia. PA (grant 9530): Janet Weis. OT. Vincent R. Hentz, MD, Amy i. Ladd, GE, and InderPerkash, MD of the Palo Alto VA Medical Center, Palo Alto, CA; Terry Retman, OT, Mark J. Koris, MD, and Allen W. Wiegner, PhD, of the West Roxbury VA Medical Center. West Roxburv. MA: Daniel P. Greenwald, Araceli Denoea. Audrey Nelson and ‘&&a Kunins of the Tampa VA Medical Center Hospital, Tampa, FL; Peter H. Gorman, MD, W. Andrew Eglseder Jr., MD, Linda Marshall, OT, and Mike Mahar of the Baltimore VA Medical Center, Baltimore, MD; Sara Carroll, Cathy Cooper, Gerard W. Sormann, MD, and Douglas J. Brown, MD, of the University of Austin Hospital in Melbourne, Australia; Paul Taylor, Julie Esnouf, and John A.E. Hobby, MD, of Salisbwy District Hospital of Salisbury, United Kingdom. 1.
2. 3.
4. 5. 6.
10.
11.
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