- Email: [email protected]
Tolerability and Effectiveness of a Neuroprosthesis for the Treatment of Footdrop in Pediatric Patients With Hemiparetic Cerebral Palsy
Original Research
Tolerability and Effectiveness of a Neuroprosthesis for the Treatment of Footdrop in Pediatric Patients With Hemiparetic Cerebral Palsy Jill R. Meilahn, DO Objective: To assess the tolerability and efficacy of a commercially available footdrop neuroprosthesis for treatment of footdrop in children with hemiparetic cerebral palsy. Design: A prospective, observational pilot study. Setting: Marshfield Clinic, Department of Physical Medicine. Participants: Ten children, ages 7-12 years, with hemiparetic cerebral palsy, who use an ankle foot orthosis (AFO) for correction of footdrop. Methods: Children replaced their AFO with a transcutaneous peroneal (fibular) nerve stimulation neuroprosthesis for 3 months. Main Outcome Measurements: The ability to tolerate fitting and programming of the device, device-recorded wear time, a daily-use diary, satisfaction survey, and secondary measures, including passive range of motion and gait laboratory measurement of gait velocity and ankle kinematics. Results: All 10 participants (100%) tolerated fitting and programming of the neuroprosthesis and wore the device for 6 weeks. Seven of 10 (70%) wore the device for the entire 3-month study period; 6 of 10 (60%) continued to use the device after study completion. Wear time varied from 2 to 11 hours per day. Tolerability and satisfaction were high; although 6 participants complained of “size” and “bulkiness” of the device, and 2 reported skin irritation. Gait velocity increased in 5 subjects (50%). Seven participants (70%) preferred the neuroprosthesis to their AFO. Conclusion: Analysis of the preliminary evidence suggests that electrical stimulation by a footdrop neuroprosthesis is tolerated well by children and is effective for the treatment of footdrop in children with hemiparetic cerebral palsy. Commercially available neuroprostheses may offer a promising alternative treatment option for children with footdrop. PM R 2013;5:503-509
INTRODUCTION Cerebral palsy refers to a heterogeneous group of static encephalopathies that permanently affect body movement and muscle coordination but that are not progressive. Treatment is intended to prevent secondary complications and maximize function [1]. Ankle dorsiflexion weakness, or footdrop, is a common effect of cerebral palsy, and results in the patient’s inability to actively dorsiflex the ankle. Currently, children with hemiparetic cerebral palsy wear an external ankle foot orthosis (AFO) to prevent footdrop. Children frequently dislike the AFO because of discomfort and concerns with cosmesis, even though they walk better and fall less when wearing it. Untreated footdrop can result in the development of severely abnormal gait patterns and ankle plantar flexion contracture. In addition, ankle plantar flexion contractures require orthopedic surgery for correction that often needs to be repeated as the child grows [2]. Transcutaneous peroneal (fibular) nerve stimulation can counteract footdrop by producing dorsiflexion of the ankle during the swing phase of the gait [3]. Transcutaneous peroneal nerve neuroprostheses have recently been successfully developed for commercial use in adults with conditions that result in footdrop, most commonly stroke and head injury. The devices attach to the leg, just below the knee, near the fibular head. During a gait cycle, the PM&R 1934-1482/13/$36.00 Printed in U.S.A.
J.R.M. Department of Physical Medical, Marshfield Clinic, 1000 North Oak Ave, Marshfield, WI 54449. Address correspondence to: J.R.M.; e-mail: meilahn.jill@marshfieldclinic. org Disclosure: nothing to disclose Research support: Financial support for this study was provided by the Marshfield Clinic Research Foundation’s Disease Specific Research Funds. Submitted for publication June 14, 2012; accepted November 3, 2012.
© 2013 by the American Academy of Physical Medicine and Rehabilitation Vol. 5, 503-509, June 2013 http://dx.doi.org/10.1016/j.pmrj.2012.11.005
503
504
Meilahn
device stimulates the common peroneal nerve, which innervates the tibialis anterior and other muscles that produce dorsiflexion of the ankle. Several studies with transcutaneous peroneal nerve stimulation devices in hemiparetic adults with a variety of central nervous system conditions have demonstrated increased walking speed [4-7], with a possible training effect after stimulation is removed [5,7]. Although either a nerve stimulator or an AFO can improve walking function compared with no device, Sheffler et al [8] found that adult patients preferred the nerve stimulator. Despite the success of transcutaneous peroneal nerve stimulation devices in adult patients with footdrop, this method has not been fully incorporated into clinical use, possibly due to difficulties with insurance coverage, electrode placement, insufficient medial-lateral ankle support, a lack of local technical expertise, and the ready availability of custom AFOs to prevent footdrop [9]. Some clinicians have begun using transcutaneous peroneal nerve neuroprostheses in children. The company that manufactures the device has liberal anecdotal YouTube (YouTube LLC, San Bruno, CA) videos of “success stories,” but actual research studies remain quite limited. In a metaanalysis of the use of electrical stimulation in children with cerebral palsy [10], 4 studies that used functional electrical stimulation (FES) were analyzed and found to have an overall combined moderate effect on both gait impairment and activity limitation [11-14]. However, an earlier review by Seifart et al [15] found only mixed results when 5 studies of both transcutaneous and percutaneous FES were examined, although no meta-analysis was performed, and studies were excluded if testing was done with the device in place [11,1619]. At the time this study was undertaken, no rigorous study had been performed with children to test the tolerance for, or effectiveness of, the use of an external functional electrical peroneal nerve stimulator. However, a recent publication by Prosser et al [20] demonstrated that such a device is both accepted and potentially effective for the treatment of footdrop in children and adolescents with cerebral palsy. The purpose of the present study was to determine the tolerability and effectiveness of a commercially available external neuroprosthesis in a small group of pediatric patients with hemiparetic cerebral palsy who typically wear an AFO. In addition to assessing tolerance for fitting and programming of the device, device wear time, and measurements of gait, we also collected self-reported data regarding satisfaction with the device and comparison with traditional AFOs.
METHODS Participants Participants included 10 patients between the ages of 7 and 12 years with a primary diagnosis of spastic hemiparetic cerebral palsy undergoing current treatment for footdrop
NEUROPROSTHESIS IN CHILDREN WITH CP
with an AFO. Subject eligibility included the capacity to walk at least 10 feet without falling without wearing an AFO, and the capability to understand instructions for use and application of the transcutaneous peroneal neuroprosthesis. All the participants were capable of normal ambulation but were limited in gross motor skills to some extent by issues with speed, balance, and/or coordination, which resulted in a gross motor functional classification scale level of I [21]. Exclusion criteria included fixed ankle contracture, peripheral nerve injury, current or previous treatment with neuromuscular electrical stimulation, a history of heart disease, uncontrolled seizure disorder, and leg or foot surgery in the past 6 months. The patients were identified at the Marshfield Clinic, Physical Medicine Department in Marshfield, Wisconsin. The study was approved by the Marshfield Clinic’s institutional review board, and informed assent and consent were obtained from all patients and their caregivers before enrollment.
Research Design At baseline (week-2), the subjects were fitted for a neuroprosthesis. The subjects initially wore the device without electrical stimulation for a 2-week run-in period to identify whether future intolerance was due to issues with the cuff or shock. At week 0, the electrical stimulation in the neuroprosthesis was turned on and adjusted to be appropriate for children. Pulse width was decreased from 100 to 50, and the initial minimum time was set to 0.3 seconds, maximum time to 0.6 seconds, and wait time to 0.2 seconds. These novel settings made the shocks tolerable while maintaining efficacy for stimulation of ankle dorsiflexion. The time changes accommodated the shorter and faster pediatric stride. The subjects wore the device instead of their AFO for up to 3 consecutive months, with study visits at 3 weeks, 6 weeks, and 3 months. Gait laboratory analysis was performed at -2 weeks (baseline during run-in period), 0 weeks (immediately before device activation), and 3 weeks, 6 weeks, and 3 months after device activation. Each subject served as his or her own control, after becoming accustomed to the device during the run-in period, and used the active device from week 0 through 3 months and beyond if the device was effective and continued to be well tolerated.
Neuroprosthetic Device Innovative Neurotronics (Austin, TX) provided the WalkAide neuroprosthesis for use by the study participants for the duration of the study. The WalkAide is a battery-operated, singlechannel electrical stimulator that is designed to address footdrop by using FES. The WalkAide uses a tilt sensor to control stimulation during normal gait. The device is attached to the leg just below the knee near the head of the fibula. During a gait cycle, the device stimulates the common peroneal nerve, which inner-
PM&R
vates the tibialis anterior and other muscles that produce dorsiflexion of the ankle. Minor adjustments from the recommended adult settings to electrical shock intensity and duration were made for the pediatric patients enrolled in this study, as previously described. Innovative Neurotronics provided specialized training to a certified orthotist and 2 physical therapists to allow for evaluation, fitting, and customization of the WalkAide neuroprosthesis for individual subjects. The orthotist took measurements for custom fabrication of the WalkAide cuff for each individual subject and then positioned the device on the subject’s leg, below the knee. He custom made a cover for the stimulation intensity knob to prevent accidental changes from bumping or playing with the dial. The physical therapist programmed the tilt sensor and used a peripheral nerve stimulator to find the appropriate stimulation site of the common peroneal nerve to produce ankle dorsiflexion. When optimal electrode positions were found, the electrodes were attached to the cuff by using Velcro (Velcro Industries, BV, Manchester, NH), and an initial walking trial was initiated with the cuff holding the system in place. After optimization of the cuff and electrode placement, the subject and/or caregiver was instructed in correct application of the device. The subjects were also instructed that the skin around the head of the fibula must be cleaned with soap and water, and that water should then be applied to the area where the electrodes are placed, to improve conductivity. The cuff was placed below the knee on the outside of the leg, with the unit secured on the proximal medial tibia, distal to the patella. Velcro straps then secured the system in place to position the device on the leg correctly for effective and efficient stimulation. The subjects were instructed to wear the neuroprosthesis all day but to remove it before swimming, bathing, and going to bed at night. The subjects and/or caregivers were also instructed on care of the device, including battery replacement.
Gait Laboratory Evaluation The gait laboratory analysis provided an objective, technical evaluation of subject motion, including videotaping, clinical evaluation, and motion data collection of temporal spatial information, kinematics (joint range of motion during gait), and kinetics (forces at each joint during gait). Clinical evaluation included goniometric measurement of lower extremity active and passive range of motion.
Data Collection Patient demographic, diagnostic, inclusion and exclusion criteria, and fall history data were recorded by the clinical research coordinator. Self-reported device usage, fall, and physical activity information was collected by the subject and/or caregiver in a daily-use diary, as well as by the sub-
Vol. 5, Iss. 6, 2013
505
ject’s teacher or daycare provider when the device was worn at school or day care. At each study visit, the subject and/or caregiver completed a satisfaction survey that evaluated the comfort and cosmesis of the device and reported any adverse events. Gait laboratory data, including gait velocity and kinematics, were collected and analyzed by a physical therapist and a clinical engineer. The physical therapist was also responsible for downloading digital data collected by the device, which included the amount of time that the device was turned on and the number of steps taken for up to 72 days to assess compliance. Data analysis was performed by the Department of Biostatistics in the Marshfield Clinic Biomedical Informatics Research Center.
Statistical Analysis Due to the small number of participants (10 children), no formal statistical analysis was performed. The major outcomes of interest were the subjects’ compliance, comfort, and gait velocity. Descriptive statistics are reported at the baseline of the study for each of the subjects’ attributes (eg, age, gender, gait velocity, number of falls). Information on the levels of compliance, dropout, comfort, gait velocity, and the number of falls were captured during the 2 observational periods (run-in period versus working device).
RESULTS Ten children, between the ages of 7 and 12 years, with hemiparetic cerebral palsy, who usually used an AFO for footdrop, were enrolled in the study. Mean (standard deviation) age was 9.25 ⫾ 1.69 years at study enrollment. Six of the 10 subjects (60%) were boys. The left leg was affected in 4 subjects, and the right leg was affected in 6. Heterogeneous etiologies of cerebral palsy included premature birth, intrauterine stroke, and other or unknown causes in just less than half of the subjects. The majority of subjects did not receive physical therapy either at school or through an outpatient clinic. The fall history among patients was varied and ranged in frequency from daily to never. Neuroprosthesis use was recorded by the device and by the subject and/or caregiver in a daily diary (Table I). All 10 patients wore the device for at least 6 weeks. The average number of hours worn per day in the first 3 weeks after activation was 8.4 hours. In the second 3 weeks, the average device-captured wear time per day decreased to 5.8 hours (range, 0.9-10.9 h/d). Seven of 10 patients continued to wear the device up to 3 months, and the average use time captured decreased to 2.3 hours daily (range, 1.0-6.3 h/d). Six of 10 patients continued to wear the device after completion of the study. Participants appeared to underestimate the total amount of time that the device was worn. The device recorded a mean total amount of time worn of 428.79 hours, whereas the mean total amount of time worn based on daily
506
Meilahn
NEUROPROSTHESIS IN CHILDREN WITH CP
Table 1. Neuroprosthesis usage
Device recorded* Days logged 3 wk 6 wk 3 mo Daily hours 3 wk 6 wk 3 mo Total hours Self-reported No. diary days Home§ School Hours worn Home School No. falls Home School
Mean (SD)
Range
16.6 ⫾ 8.6 23.8 ⫾ 2.7 68.7 ⫾ 3.6
1-22 22-29† 64-71
8.4 ⫾ 5.4 5.8 ⫾ 3.7 2.3 ⫾ 2.0 428.8 ⫾ 296.2
2.7-19.5‡ 0.9-10.9 1.0-6.3 106.4-932.9
54.9 ⫾ 4.5 29.2 ⫾ 13.5
44-59 0-49
314.4 ⫾ 118.0 158.9 ⫾ 81.2
149.5-458.5 0.0-272.0
5.9 ⫾ 9.1 1.2 ⫾ 1.3
0-26 0-3
*Device-recorded usage is missing for 4 participants at the 3-mo time point; data for 2 subjects was not recorded due to technical error, and 2 subjects dropped out of the study after the 6-wk time point. † The device erroneously recorded 71 days of use in the 3-wk period from the 3-wk to 6-wk time points for 2 participants; these values were excluded from the analysis. ‡ The device erroneously recorded 24.6 h of daily use for 1 participant; this value was excluded from the analysis. § Home diary recordings included wear time at home and school.
diary reports was 314.4 hours (Table 1). The subjects were asked to record a reason from a menu of choices for removing the device when worn for less than 4 hours at a time. Choices included discomfort, embarrassment, trouble walking, and other. No participants reported trouble walking. The mean number of times that a subject reported embarrassment as the reason for not wearing the device was 0.5 times at home (range, 0-3 times) but never at school. The mean number of times that discomfort was cited as the reason for not wearing the device was 2.3 times at home (range, 0-10 times) and 0.2 times at school (range, 0-2 times). “Other” was cited as a reason for not wearing the device a mean number of 7.3 times at home (range, 0-21 times) and 1.1 times at school (range,
0-4 times). When asked for descriptions of the other reasons, participant responses included skin irritation, improper cuff fit, bulkiness of cuff, or electrodes becoming “unstuck.” At each study visit, the participants were asked to agree or disagree with a series of statements regarding overall satisfaction with the WalkAide neuroprosthesis. The majority of subjects were either neutral or agreed with statements that suggested that the device was comfortable, was easy to put on and take off, improved walking ability, increased physical activity level, was preferred over the usual AFO, and was overall satisfying. The majority of subjects either were neutral or disagreed that wearing the device was embarrassing (Table 2). Measures of effectiveness included assessment of gait velocity, ankle dorsiflexion, and participation in physical activity. Five subjects (50%) showed improvement in gait velocity over the course of the study, whereas others remained relatively consistent (Figure 1A and B). Gait laboratory analysis demonstrated normalization of ankle kinematics in 3 patients (Figure 1C); however, no consistent trend in the change of range of motion was observed (Figure 2). Several subjects reported participation in a variety of physical activities, including bicycling, dancing, hiking, jogging or running, jumping rope, skating, basketball, football, hockey, soccer, and volleyball, both at home and at school while wearing the neuroprosthesis. One participant also reported wrestling with the device removed. The most frequent activities in which subjects participated were bicycling and jogging or running. Notably, 8 of 9 subjects (89%) preferred the device over their normal AFO at 3 weeks, 7 of 9 (78%) at 6 weeks, and 5 of 7 (71%) at 3 months. The only adverse event reported by patients was skin irritation caused by the electrodes. New hypoallergenic electrodes are now available.
DISCUSSION Analysis of the results of this study suggests that the use of a transcutaneous peroneal nerve stimulation device for the treatment of footdrop is well tolerated by pediatric patients with hemiparetic cerebral palsy. Over time, the neuroprosthesis was favored over the AFO by the majority of study
Table 2. Subject satisfaction Average Level of Agreement* Statement
0 wk
3 wk
6 wk
3 mo
Wearing the WalkAide during my waking hours was comfortable. The WalkAide was easy to put on and take off. My walking ability was improved by wearing the WalkAide. My physical activity level was increased by wearing the WalkAide. I prefer the WalkAide instead of my usual ankle foot orthosis. Overall, I am very satisfied with the WalkAide. Wearing the WalkAide was embarrassing.
1.7 1.4 3.2 3.0 1.5 2.4 4.1
1.9 2.2 2.3 2.5 1.7 1.7 4.1
2.0 1.5 1.9 1.9 1.8 1.7 3.6
3.0 2.4 1.8 1.9 1.9 2.1 3.7
*Agreement was measured on a scale of 1-5, with 1 being “strongly agree” and 5 being “strongly disagree.”
PM&R
Figure 1. Gait laboratory analysis. Gait velocity in affected and in normal legs is shown in (A) and (B), respectively. Each line represents an individual participant, with the mean indicated in bold. Five participants showed an increase in gait velocity over time in the affected leg, as indicated by the dashed line. Three subjects dropped out of the study before the final gait laboratory analysis. (C) A representative subject, demonstrating normalization in ankle kinematics over time. Negative values indicate plantar flexion, and positive values indicate dorsiflexion. The shaded area encompasses the normal range. LHS ⫽ left heel strike; LTO ⫽ left toe off; RHS ⫽ right heel strike; RTO ⫽ right toe off.
participants. True efficacy of the nerve stimulation device is difficult to assess due to the small size of the study group; however, some subjects did manifest improvement in gait velocity and ankle kinematics over the course of the study. These findings are consistent with several other studies of FES in children. Postans and Granat [22] observed normalization of ankle kinematics when FES strategies were tailored to children with hemiplegic or diplegic cerebral palsy. Dur-
Vol. 5, Iss. 6, 2013
507
ham et al [11] observed an immediate orthotic effect in children with hemiplegic cerebral palsy during FES applied to the tibialis anterior. Similarly, van der Linden et al [14] observed an orthotic effect of FES of the dorsiflexors in a small, randomized, controlled trial, but neuromuscular electrical stimulation was applied for 2 weeks before FES, potentially confounding the results. In a more recent study by Prosser et al [20], an FES device was well accepted and effective for footdrop in pediatric and adolescent patients with cerebral palsy as measured by wear time and gait laboratory analysis. In the present study, perhaps the most telling sign of efficacy is the opinion of the participants on the satisfaction survey administered at each study visit. In response to the statement “I think my walking ability was improved by wearing the WalkAide neuroprosthesis,” 7 of 10 subjects (70%) agreed or strongly agreed at 3 and 6 weeks, and 6 of 8 (75%) agreed or strongly agreed at 3 months (Table 2). Currently, children with hemiparetic cerebral palsy wear an AFO to prevent footdrop. New orthoses are needed, approximately yearly, as the child grows. Each new orthosis necessitates a physician visit to generate the prescription, a visit to the orthotist for molding, a return visit to the orthotist for fitting, and frequent repeat visits for padding, straps, and other adjustments for a comfortable fit. Each orthosis costs approximately $750. The initial cost for a transcutaneous peroneal neuroprosthesis is currently approximately $4500. The same cuff can be adjusted for growth without significant additional expense (each cuff costs less than $100 and should last several years). There have also been early reports that the neuroprostheses may have a training effect [23,24], which results in improved patient control of footdrop even without the device. The potential for improved patient compliance at potentially lower cost over time, normalization of gait patterns, and prevention of ankle plantar flexion contractures make further exploration of this technology intriguing, especially in light of the evidence presented in this study, which suggests both tolerability and efficacy in pediatric patients. Further testing to determine the efficacy of neuroprosthetic devices in children in comparison with the AFO is necessary. Importantly, if demonstrated to achieve comparable or better efficacy, then the nerve stimulation device would provide an alternative treatment option for children with footdrop. Children often refuse to wear an AFO, which may result in the development of severely abnormal gait patterns and ankle plantar flexion contractures. Retraining a child’s learned motor patterns after 8 years of age can be difficult, and ankle plantar flexion contractures may require a series of orthopedic surgeries for correction as the child grows. Availability of an alternative treatment option for children with footdrop could increase the likelihood that children would be willing to wear at least one of the prostheses, avoiding the complications associated with untreated footdrop.
508
Meilahn
NEUROPROSTHESIS IN CHILDREN WITH CP
Figure 2. Passive range of motion. Ankle dorsiflexion was measured at each time point with a straight knee (A and B) and bent knee (C and D) in the affected leg (A and C) and the normal leg (B and D). Negative values indicate the participant could not achieve the 90° position of the ankle. Triangles represent the mean, with the numerical value to the right, and with range indicated.
The obvious major limitation of this study is the small sample size. In addition, the study subjects were self-selected by having expressed an interest in trying the device. However, as one of the first studies to demonstrate the tolerability and potential efficacy of a commercialy available transperoneal nerve stimulation device during daily use in a pediatric population, it serves as an impetus for the further testing and development of such devices for use with children. Furthermore, the device used in the present study was not designed specifically for children. Issues related to fit due to cuff size may have influenced wear time to some extent. Fortunately, research in the field has prompted further innovation and development of a device designed specifically for pediatric patients, which is now commercially available.
ACKNOWLEDGMENTS
CONCLUSION
REFERENCES
Future studies with neuroprostheses will be needed to compare efficacy to the standard of care, AFO, to examine evidence of a neurotraining effect, and to clarify the optimal age for application. In addition, assessment of whether a transperoneal nerve stimulation device may apply to footdrop in pediatric patients with other conditions (diplegic cerebral palsy, spina bifida, spinal cord injury, or traumatic brain injury) would be worthwhile if the devices continue to show promise in the current application after more rigorous assessment in future studies. Results from this pilot study and the recently published study by Prosser et al [20] provide the preliminary data necessary to inform design, sample size, and methodology for future research on a promising alternative therapy for children with footdrop.
The author would like to acknowledge Innovative Neurotronics (Austin, TX) for donating without condition the device that was utilized in the study. The author additionally thanks the physical therapists Ashley Detterbeck and Karna Sandok, her nurse Kaye Andreae, and the gait lab technician Melanie Annala, without whom this study could not have been accomplished. The author also thanks Po-Huang Chyou, PhD, of the Marshfield Clinic Research Foundation’s Biomedical Informatics Research Center, for providing statistcal assistance, as well as the Marshfield Clinic Research Foundation’s Office of Scientific Writing and Publication for assistance in the preparation of this manuscript.
1. Mayston MJ. People with cerebral palsy: Effects of and perspectives for therapy. Neural Plast 2001;8:51-69. 2. Morris C. A review of the efficacy of lower-limb orthoses used for cerebral palsy. Dev Med Child Neurol 2002;44:205-211. 3. Liberson WT, Homquest HJ, Scot D, Dow M. Functional electrotherapy: Stimulation of the peroneal nerve synchronized with the swing phase of the gait of hemiplegic patients. Arch Phys Med Rehabil 1961; 42:101-105. 4. Burridge JH, Taylor PN, Hagan SA, Wood DE, Swain ID. The effects of common peroneal stimulation on the effort and speed of walking: A randomized controlled trial with chronic hemiplegic patients. Clin Rehabil 1997;11:201-210. 5. Stein RB, Chong S, Everaert DG, et al. A multicenter trial of a footdrop stimulator controlled by a tilt sensor. Neurorehabil Neural Repair 2006;20:371-379. 6. Kottink AI, Hermens HJ, Nene AV, et al. A randomized controlled trial of an implantable 2-channel peroneal nerve stimulator on walking
PM&R
7.
8.
9. 10.
11.
12.
13.
14.
15.
speed and activity in poststroke hemiplegia. Arch Phys Med Rehabil 2007;88:971-978. Stein RB, Rolf R, Everaert DG, Bobet J, Chong S. Surface electrical stimulation for foot drop: Control aspects and walking performance. J Automat Control 2008;18:47-52. Sheffler LR, Hennessey MT, Naples GG, Chae J. Peroneal nerve stimulation versus an ankle foot orthosis for correction of footdrop on stroke: Impact on functional ambulation. Neurorehabil Neural Repair 2006; 20:355-360. Sheffler L, Chae J. Neuromuscular electrical stimulation in neurorehabilitation. Muscle Nerve 2007;35:562-590. Cauraugh JH, Naik SK, Hsu WH, Coombes SA, Holt KH. Children with cerebral palsy: A systematic review and meta-analysis on gait and electrical stimulation. Clin Rehab 2010;24:963-978. Durham S, Eve L, Stevens C, Ewins D. Effect of functional electrical stimulation on asymmetries in gait of children with hemiplegic cerebral palsy. Physiotherapy 2004;90:82-90. Johnston TE, Finson RL, McCarthy JJ, Smith BT, Betz RR, Mulcahey MJ. Use of functional electrical stimulation to augment traditional orthopaedic surgery in children with cerebral palsy. J Pediatr Orthop 2004; 24:283-291. Ho CL, Holt KG, Saltzman E, Wagenaar RC. Functional electrical stimulation changes dynamic resources in children with spastic cerebral palsy. Phys Ther 2006;86:987-1000. van der Linden ML, Hazlewood ME, Hillman SJ, Robb JE. Functional electrical stimulation to the dorsiflexors and quadriceps in children with cerebral palsy. Pediatr Phys Ther 2008;20:23-29. Seifart A, Unger M, Burger M. The effect of lower limb functional electrical stimulation on gait of children with cerebral palsy. Pediatr Phys Ther 2009;21:23-30.
Vol. 5, Iss. 6, 2013
509
16. Carmick J. Clinical use of neuromuscular electrical stimulation for children with cerebral palsy, part 1: Lower extremity. Phys Ther 1993;73:505-513. 17. Bertoti SB, Stanger M, Betz RR, Akers J, Maynahon M, Mulcahey MJ. Percutaneous intramuscular function electrical stimulation as an intervention choice for children with cerebral palsy. Pediatr Phys Ther 1997;9:123-127. 18. Comeaux P, Patterson N, Rubin M, Meiner R. Effect of neuromuscular electrical stimulation during gait in children with cerebral palsy. Pediatr Phys Ther 1997;9:103-109. 19. Pierce SR, Laughton CA, Smith BT, Orlin MN, Johnston TE, McCarthy JJ. Direct effect of percutaneous electric stimulation during gait in children with hemiplegic cerebral palsy: A report of 2 cases. Arch Phys Med Rehabil 2004;85:339-343. 20. Prosser LA, Curatalo LA, Alter KE, Damiano DL. Acceptability and potential effectiveness of a foot drop stimulator in children and adolescents with cerebral palsy. Dev Med Child Neurol 2012;54:1044-1049. 21. Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B. Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39:214223. 22. Postans NJ, Granat MH. Effect of functional electrical stimulation, applied during walking, on gait in spastic cerebral palsy. Dev Med Child Neurol 2005;47:46-52. 23. Rushton DN. Function electrical stimulation and rehabilitation: An hypothesis. Med Eng Phys 2003;25:75-78. 24. Laufer Y, Ring H, Sprecher E, Hausdorff JM. Gait in individuals with chronic hemiparesis: One-year follow-up of the effects of a neuroprosthesis that ameliorates foot drop. J Neurol Phys Ther 2009;33:104-110.
Tolerability and Effectiveness of a Neuroprosthesis for the Treatment of Footdrop in Pediatric Patients With Hemiparetic Cerebral Palsy Jill R. Meilahn, DO Objective: To assess the tolerability and efficacy of a commercially available footdrop neuroprosthesis for treatment of footdrop in children with hemiparetic cerebral palsy. Design: A prospective, observational pilot study. Setting: Marshfield Clinic, Department of Physical Medicine. Participants: Ten children, ages 7-12 years, with hemiparetic cerebral palsy, who use an ankle foot orthosis (AFO) for correction of footdrop. Methods: Children replaced their AFO with a transcutaneous peroneal (fibular) nerve stimulation neuroprosthesis for 3 months. Main Outcome Measurements: The ability to tolerate fitting and programming of the device, device-recorded wear time, a daily-use diary, satisfaction survey, and secondary measures, including passive range of motion and gait laboratory measurement of gait velocity and ankle kinematics. Results: All 10 participants (100%) tolerated fitting and programming of the neuroprosthesis and wore the device for 6 weeks. Seven of 10 (70%) wore the device for the entire 3-month study period; 6 of 10 (60%) continued to use the device after study completion. Wear time varied from 2 to 11 hours per day. Tolerability and satisfaction were high; although 6 participants complained of “size” and “bulkiness” of the device, and 2 reported skin irritation. Gait velocity increased in 5 subjects (50%). Seven participants (70%) preferred the neuroprosthesis to their AFO. Conclusion: Analysis of the preliminary evidence suggests that electrical stimulation by a footdrop neuroprosthesis is tolerated well by children and is effective for the treatment of footdrop in children with hemiparetic cerebral palsy. Commercially available neuroprostheses may offer a promising alternative treatment option for children with footdrop. PM R 2013;5:503-509
INTRODUCTION Cerebral palsy refers to a heterogeneous group of static encephalopathies that permanently affect body movement and muscle coordination but that are not progressive. Treatment is intended to prevent secondary complications and maximize function [1]. Ankle dorsiflexion weakness, or footdrop, is a common effect of cerebral palsy, and results in the patient’s inability to actively dorsiflex the ankle. Currently, children with hemiparetic cerebral palsy wear an external ankle foot orthosis (AFO) to prevent footdrop. Children frequently dislike the AFO because of discomfort and concerns with cosmesis, even though they walk better and fall less when wearing it. Untreated footdrop can result in the development of severely abnormal gait patterns and ankle plantar flexion contracture. In addition, ankle plantar flexion contractures require orthopedic surgery for correction that often needs to be repeated as the child grows [2]. Transcutaneous peroneal (fibular) nerve stimulation can counteract footdrop by producing dorsiflexion of the ankle during the swing phase of the gait [3]. Transcutaneous peroneal nerve neuroprostheses have recently been successfully developed for commercial use in adults with conditions that result in footdrop, most commonly stroke and head injury. The devices attach to the leg, just below the knee, near the fibular head. During a gait cycle, the PM&R 1934-1482/13/$36.00 Printed in U.S.A.
J.R.M. Department of Physical Medical, Marshfield Clinic, 1000 North Oak Ave, Marshfield, WI 54449. Address correspondence to: J.R.M.; e-mail: meilahn.jill@marshfieldclinic. org Disclosure: nothing to disclose Research support: Financial support for this study was provided by the Marshfield Clinic Research Foundation’s Disease Specific Research Funds. Submitted for publication June 14, 2012; accepted November 3, 2012.
© 2013 by the American Academy of Physical Medicine and Rehabilitation Vol. 5, 503-509, June 2013 http://dx.doi.org/10.1016/j.pmrj.2012.11.005
503
504
Meilahn
device stimulates the common peroneal nerve, which innervates the tibialis anterior and other muscles that produce dorsiflexion of the ankle. Several studies with transcutaneous peroneal nerve stimulation devices in hemiparetic adults with a variety of central nervous system conditions have demonstrated increased walking speed [4-7], with a possible training effect after stimulation is removed [5,7]. Although either a nerve stimulator or an AFO can improve walking function compared with no device, Sheffler et al [8] found that adult patients preferred the nerve stimulator. Despite the success of transcutaneous peroneal nerve stimulation devices in adult patients with footdrop, this method has not been fully incorporated into clinical use, possibly due to difficulties with insurance coverage, electrode placement, insufficient medial-lateral ankle support, a lack of local technical expertise, and the ready availability of custom AFOs to prevent footdrop [9]. Some clinicians have begun using transcutaneous peroneal nerve neuroprostheses in children. The company that manufactures the device has liberal anecdotal YouTube (YouTube LLC, San Bruno, CA) videos of “success stories,” but actual research studies remain quite limited. In a metaanalysis of the use of electrical stimulation in children with cerebral palsy [10], 4 studies that used functional electrical stimulation (FES) were analyzed and found to have an overall combined moderate effect on both gait impairment and activity limitation [11-14]. However, an earlier review by Seifart et al [15] found only mixed results when 5 studies of both transcutaneous and percutaneous FES were examined, although no meta-analysis was performed, and studies were excluded if testing was done with the device in place [11,1619]. At the time this study was undertaken, no rigorous study had been performed with children to test the tolerance for, or effectiveness of, the use of an external functional electrical peroneal nerve stimulator. However, a recent publication by Prosser et al [20] demonstrated that such a device is both accepted and potentially effective for the treatment of footdrop in children and adolescents with cerebral palsy. The purpose of the present study was to determine the tolerability and effectiveness of a commercially available external neuroprosthesis in a small group of pediatric patients with hemiparetic cerebral palsy who typically wear an AFO. In addition to assessing tolerance for fitting and programming of the device, device wear time, and measurements of gait, we also collected self-reported data regarding satisfaction with the device and comparison with traditional AFOs.
METHODS Participants Participants included 10 patients between the ages of 7 and 12 years with a primary diagnosis of spastic hemiparetic cerebral palsy undergoing current treatment for footdrop
NEUROPROSTHESIS IN CHILDREN WITH CP
with an AFO. Subject eligibility included the capacity to walk at least 10 feet without falling without wearing an AFO, and the capability to understand instructions for use and application of the transcutaneous peroneal neuroprosthesis. All the participants were capable of normal ambulation but were limited in gross motor skills to some extent by issues with speed, balance, and/or coordination, which resulted in a gross motor functional classification scale level of I [21]. Exclusion criteria included fixed ankle contracture, peripheral nerve injury, current or previous treatment with neuromuscular electrical stimulation, a history of heart disease, uncontrolled seizure disorder, and leg or foot surgery in the past 6 months. The patients were identified at the Marshfield Clinic, Physical Medicine Department in Marshfield, Wisconsin. The study was approved by the Marshfield Clinic’s institutional review board, and informed assent and consent were obtained from all patients and their caregivers before enrollment.
Research Design At baseline (week-2), the subjects were fitted for a neuroprosthesis. The subjects initially wore the device without electrical stimulation for a 2-week run-in period to identify whether future intolerance was due to issues with the cuff or shock. At week 0, the electrical stimulation in the neuroprosthesis was turned on and adjusted to be appropriate for children. Pulse width was decreased from 100 to 50, and the initial minimum time was set to 0.3 seconds, maximum time to 0.6 seconds, and wait time to 0.2 seconds. These novel settings made the shocks tolerable while maintaining efficacy for stimulation of ankle dorsiflexion. The time changes accommodated the shorter and faster pediatric stride. The subjects wore the device instead of their AFO for up to 3 consecutive months, with study visits at 3 weeks, 6 weeks, and 3 months. Gait laboratory analysis was performed at -2 weeks (baseline during run-in period), 0 weeks (immediately before device activation), and 3 weeks, 6 weeks, and 3 months after device activation. Each subject served as his or her own control, after becoming accustomed to the device during the run-in period, and used the active device from week 0 through 3 months and beyond if the device was effective and continued to be well tolerated.
Neuroprosthetic Device Innovative Neurotronics (Austin, TX) provided the WalkAide neuroprosthesis for use by the study participants for the duration of the study. The WalkAide is a battery-operated, singlechannel electrical stimulator that is designed to address footdrop by using FES. The WalkAide uses a tilt sensor to control stimulation during normal gait. The device is attached to the leg just below the knee near the head of the fibula. During a gait cycle, the device stimulates the common peroneal nerve, which inner-
PM&R
vates the tibialis anterior and other muscles that produce dorsiflexion of the ankle. Minor adjustments from the recommended adult settings to electrical shock intensity and duration were made for the pediatric patients enrolled in this study, as previously described. Innovative Neurotronics provided specialized training to a certified orthotist and 2 physical therapists to allow for evaluation, fitting, and customization of the WalkAide neuroprosthesis for individual subjects. The orthotist took measurements for custom fabrication of the WalkAide cuff for each individual subject and then positioned the device on the subject’s leg, below the knee. He custom made a cover for the stimulation intensity knob to prevent accidental changes from bumping or playing with the dial. The physical therapist programmed the tilt sensor and used a peripheral nerve stimulator to find the appropriate stimulation site of the common peroneal nerve to produce ankle dorsiflexion. When optimal electrode positions were found, the electrodes were attached to the cuff by using Velcro (Velcro Industries, BV, Manchester, NH), and an initial walking trial was initiated with the cuff holding the system in place. After optimization of the cuff and electrode placement, the subject and/or caregiver was instructed in correct application of the device. The subjects were also instructed that the skin around the head of the fibula must be cleaned with soap and water, and that water should then be applied to the area where the electrodes are placed, to improve conductivity. The cuff was placed below the knee on the outside of the leg, with the unit secured on the proximal medial tibia, distal to the patella. Velcro straps then secured the system in place to position the device on the leg correctly for effective and efficient stimulation. The subjects were instructed to wear the neuroprosthesis all day but to remove it before swimming, bathing, and going to bed at night. The subjects and/or caregivers were also instructed on care of the device, including battery replacement.
Gait Laboratory Evaluation The gait laboratory analysis provided an objective, technical evaluation of subject motion, including videotaping, clinical evaluation, and motion data collection of temporal spatial information, kinematics (joint range of motion during gait), and kinetics (forces at each joint during gait). Clinical evaluation included goniometric measurement of lower extremity active and passive range of motion.
Data Collection Patient demographic, diagnostic, inclusion and exclusion criteria, and fall history data were recorded by the clinical research coordinator. Self-reported device usage, fall, and physical activity information was collected by the subject and/or caregiver in a daily-use diary, as well as by the sub-
Vol. 5, Iss. 6, 2013
505
ject’s teacher or daycare provider when the device was worn at school or day care. At each study visit, the subject and/or caregiver completed a satisfaction survey that evaluated the comfort and cosmesis of the device and reported any adverse events. Gait laboratory data, including gait velocity and kinematics, were collected and analyzed by a physical therapist and a clinical engineer. The physical therapist was also responsible for downloading digital data collected by the device, which included the amount of time that the device was turned on and the number of steps taken for up to 72 days to assess compliance. Data analysis was performed by the Department of Biostatistics in the Marshfield Clinic Biomedical Informatics Research Center.
Statistical Analysis Due to the small number of participants (10 children), no formal statistical analysis was performed. The major outcomes of interest were the subjects’ compliance, comfort, and gait velocity. Descriptive statistics are reported at the baseline of the study for each of the subjects’ attributes (eg, age, gender, gait velocity, number of falls). Information on the levels of compliance, dropout, comfort, gait velocity, and the number of falls were captured during the 2 observational periods (run-in period versus working device).
RESULTS Ten children, between the ages of 7 and 12 years, with hemiparetic cerebral palsy, who usually used an AFO for footdrop, were enrolled in the study. Mean (standard deviation) age was 9.25 ⫾ 1.69 years at study enrollment. Six of the 10 subjects (60%) were boys. The left leg was affected in 4 subjects, and the right leg was affected in 6. Heterogeneous etiologies of cerebral palsy included premature birth, intrauterine stroke, and other or unknown causes in just less than half of the subjects. The majority of subjects did not receive physical therapy either at school or through an outpatient clinic. The fall history among patients was varied and ranged in frequency from daily to never. Neuroprosthesis use was recorded by the device and by the subject and/or caregiver in a daily diary (Table I). All 10 patients wore the device for at least 6 weeks. The average number of hours worn per day in the first 3 weeks after activation was 8.4 hours. In the second 3 weeks, the average device-captured wear time per day decreased to 5.8 hours (range, 0.9-10.9 h/d). Seven of 10 patients continued to wear the device up to 3 months, and the average use time captured decreased to 2.3 hours daily (range, 1.0-6.3 h/d). Six of 10 patients continued to wear the device after completion of the study. Participants appeared to underestimate the total amount of time that the device was worn. The device recorded a mean total amount of time worn of 428.79 hours, whereas the mean total amount of time worn based on daily
506
Meilahn
NEUROPROSTHESIS IN CHILDREN WITH CP
Table 1. Neuroprosthesis usage
Device recorded* Days logged 3 wk 6 wk 3 mo Daily hours 3 wk 6 wk 3 mo Total hours Self-reported No. diary days Home§ School Hours worn Home School No. falls Home School
Mean (SD)
Range
16.6 ⫾ 8.6 23.8 ⫾ 2.7 68.7 ⫾ 3.6
1-22 22-29† 64-71
8.4 ⫾ 5.4 5.8 ⫾ 3.7 2.3 ⫾ 2.0 428.8 ⫾ 296.2
2.7-19.5‡ 0.9-10.9 1.0-6.3 106.4-932.9
54.9 ⫾ 4.5 29.2 ⫾ 13.5
44-59 0-49
314.4 ⫾ 118.0 158.9 ⫾ 81.2
149.5-458.5 0.0-272.0
5.9 ⫾ 9.1 1.2 ⫾ 1.3
0-26 0-3
*Device-recorded usage is missing for 4 participants at the 3-mo time point; data for 2 subjects was not recorded due to technical error, and 2 subjects dropped out of the study after the 6-wk time point. † The device erroneously recorded 71 days of use in the 3-wk period from the 3-wk to 6-wk time points for 2 participants; these values were excluded from the analysis. ‡ The device erroneously recorded 24.6 h of daily use for 1 participant; this value was excluded from the analysis. § Home diary recordings included wear time at home and school.
diary reports was 314.4 hours (Table 1). The subjects were asked to record a reason from a menu of choices for removing the device when worn for less than 4 hours at a time. Choices included discomfort, embarrassment, trouble walking, and other. No participants reported trouble walking. The mean number of times that a subject reported embarrassment as the reason for not wearing the device was 0.5 times at home (range, 0-3 times) but never at school. The mean number of times that discomfort was cited as the reason for not wearing the device was 2.3 times at home (range, 0-10 times) and 0.2 times at school (range, 0-2 times). “Other” was cited as a reason for not wearing the device a mean number of 7.3 times at home (range, 0-21 times) and 1.1 times at school (range,
0-4 times). When asked for descriptions of the other reasons, participant responses included skin irritation, improper cuff fit, bulkiness of cuff, or electrodes becoming “unstuck.” At each study visit, the participants were asked to agree or disagree with a series of statements regarding overall satisfaction with the WalkAide neuroprosthesis. The majority of subjects were either neutral or agreed with statements that suggested that the device was comfortable, was easy to put on and take off, improved walking ability, increased physical activity level, was preferred over the usual AFO, and was overall satisfying. The majority of subjects either were neutral or disagreed that wearing the device was embarrassing (Table 2). Measures of effectiveness included assessment of gait velocity, ankle dorsiflexion, and participation in physical activity. Five subjects (50%) showed improvement in gait velocity over the course of the study, whereas others remained relatively consistent (Figure 1A and B). Gait laboratory analysis demonstrated normalization of ankle kinematics in 3 patients (Figure 1C); however, no consistent trend in the change of range of motion was observed (Figure 2). Several subjects reported participation in a variety of physical activities, including bicycling, dancing, hiking, jogging or running, jumping rope, skating, basketball, football, hockey, soccer, and volleyball, both at home and at school while wearing the neuroprosthesis. One participant also reported wrestling with the device removed. The most frequent activities in which subjects participated were bicycling and jogging or running. Notably, 8 of 9 subjects (89%) preferred the device over their normal AFO at 3 weeks, 7 of 9 (78%) at 6 weeks, and 5 of 7 (71%) at 3 months. The only adverse event reported by patients was skin irritation caused by the electrodes. New hypoallergenic electrodes are now available.
DISCUSSION Analysis of the results of this study suggests that the use of a transcutaneous peroneal nerve stimulation device for the treatment of footdrop is well tolerated by pediatric patients with hemiparetic cerebral palsy. Over time, the neuroprosthesis was favored over the AFO by the majority of study
Table 2. Subject satisfaction Average Level of Agreement* Statement
0 wk
3 wk
6 wk
3 mo
Wearing the WalkAide during my waking hours was comfortable. The WalkAide was easy to put on and take off. My walking ability was improved by wearing the WalkAide. My physical activity level was increased by wearing the WalkAide. I prefer the WalkAide instead of my usual ankle foot orthosis. Overall, I am very satisfied with the WalkAide. Wearing the WalkAide was embarrassing.
1.7 1.4 3.2 3.0 1.5 2.4 4.1
1.9 2.2 2.3 2.5 1.7 1.7 4.1
2.0 1.5 1.9 1.9 1.8 1.7 3.6
3.0 2.4 1.8 1.9 1.9 2.1 3.7
*Agreement was measured on a scale of 1-5, with 1 being “strongly agree” and 5 being “strongly disagree.”
PM&R
Figure 1. Gait laboratory analysis. Gait velocity in affected and in normal legs is shown in (A) and (B), respectively. Each line represents an individual participant, with the mean indicated in bold. Five participants showed an increase in gait velocity over time in the affected leg, as indicated by the dashed line. Three subjects dropped out of the study before the final gait laboratory analysis. (C) A representative subject, demonstrating normalization in ankle kinematics over time. Negative values indicate plantar flexion, and positive values indicate dorsiflexion. The shaded area encompasses the normal range. LHS ⫽ left heel strike; LTO ⫽ left toe off; RHS ⫽ right heel strike; RTO ⫽ right toe off.
participants. True efficacy of the nerve stimulation device is difficult to assess due to the small size of the study group; however, some subjects did manifest improvement in gait velocity and ankle kinematics over the course of the study. These findings are consistent with several other studies of FES in children. Postans and Granat [22] observed normalization of ankle kinematics when FES strategies were tailored to children with hemiplegic or diplegic cerebral palsy. Dur-
Vol. 5, Iss. 6, 2013
507
ham et al [11] observed an immediate orthotic effect in children with hemiplegic cerebral palsy during FES applied to the tibialis anterior. Similarly, van der Linden et al [14] observed an orthotic effect of FES of the dorsiflexors in a small, randomized, controlled trial, but neuromuscular electrical stimulation was applied for 2 weeks before FES, potentially confounding the results. In a more recent study by Prosser et al [20], an FES device was well accepted and effective for footdrop in pediatric and adolescent patients with cerebral palsy as measured by wear time and gait laboratory analysis. In the present study, perhaps the most telling sign of efficacy is the opinion of the participants on the satisfaction survey administered at each study visit. In response to the statement “I think my walking ability was improved by wearing the WalkAide neuroprosthesis,” 7 of 10 subjects (70%) agreed or strongly agreed at 3 and 6 weeks, and 6 of 8 (75%) agreed or strongly agreed at 3 months (Table 2). Currently, children with hemiparetic cerebral palsy wear an AFO to prevent footdrop. New orthoses are needed, approximately yearly, as the child grows. Each new orthosis necessitates a physician visit to generate the prescription, a visit to the orthotist for molding, a return visit to the orthotist for fitting, and frequent repeat visits for padding, straps, and other adjustments for a comfortable fit. Each orthosis costs approximately $750. The initial cost for a transcutaneous peroneal neuroprosthesis is currently approximately $4500. The same cuff can be adjusted for growth without significant additional expense (each cuff costs less than $100 and should last several years). There have also been early reports that the neuroprostheses may have a training effect [23,24], which results in improved patient control of footdrop even without the device. The potential for improved patient compliance at potentially lower cost over time, normalization of gait patterns, and prevention of ankle plantar flexion contractures make further exploration of this technology intriguing, especially in light of the evidence presented in this study, which suggests both tolerability and efficacy in pediatric patients. Further testing to determine the efficacy of neuroprosthetic devices in children in comparison with the AFO is necessary. Importantly, if demonstrated to achieve comparable or better efficacy, then the nerve stimulation device would provide an alternative treatment option for children with footdrop. Children often refuse to wear an AFO, which may result in the development of severely abnormal gait patterns and ankle plantar flexion contractures. Retraining a child’s learned motor patterns after 8 years of age can be difficult, and ankle plantar flexion contractures may require a series of orthopedic surgeries for correction as the child grows. Availability of an alternative treatment option for children with footdrop could increase the likelihood that children would be willing to wear at least one of the prostheses, avoiding the complications associated with untreated footdrop.
508
Meilahn
NEUROPROSTHESIS IN CHILDREN WITH CP
Figure 2. Passive range of motion. Ankle dorsiflexion was measured at each time point with a straight knee (A and B) and bent knee (C and D) in the affected leg (A and C) and the normal leg (B and D). Negative values indicate the participant could not achieve the 90° position of the ankle. Triangles represent the mean, with the numerical value to the right, and with range indicated.
The obvious major limitation of this study is the small sample size. In addition, the study subjects were self-selected by having expressed an interest in trying the device. However, as one of the first studies to demonstrate the tolerability and potential efficacy of a commercialy available transperoneal nerve stimulation device during daily use in a pediatric population, it serves as an impetus for the further testing and development of such devices for use with children. Furthermore, the device used in the present study was not designed specifically for children. Issues related to fit due to cuff size may have influenced wear time to some extent. Fortunately, research in the field has prompted further innovation and development of a device designed specifically for pediatric patients, which is now commercially available.
ACKNOWLEDGMENTS
CONCLUSION
REFERENCES
Future studies with neuroprostheses will be needed to compare efficacy to the standard of care, AFO, to examine evidence of a neurotraining effect, and to clarify the optimal age for application. In addition, assessment of whether a transperoneal nerve stimulation device may apply to footdrop in pediatric patients with other conditions (diplegic cerebral palsy, spina bifida, spinal cord injury, or traumatic brain injury) would be worthwhile if the devices continue to show promise in the current application after more rigorous assessment in future studies. Results from this pilot study and the recently published study by Prosser et al [20] provide the preliminary data necessary to inform design, sample size, and methodology for future research on a promising alternative therapy for children with footdrop.
The author would like to acknowledge Innovative Neurotronics (Austin, TX) for donating without condition the device that was utilized in the study. The author additionally thanks the physical therapists Ashley Detterbeck and Karna Sandok, her nurse Kaye Andreae, and the gait lab technician Melanie Annala, without whom this study could not have been accomplished. The author also thanks Po-Huang Chyou, PhD, of the Marshfield Clinic Research Foundation’s Biomedical Informatics Research Center, for providing statistcal assistance, as well as the Marshfield Clinic Research Foundation’s Office of Scientific Writing and Publication for assistance in the preparation of this manuscript.
1. Mayston MJ. People with cerebral palsy: Effects of and perspectives for therapy. Neural Plast 2001;8:51-69. 2. Morris C. A review of the efficacy of lower-limb orthoses used for cerebral palsy. Dev Med Child Neurol 2002;44:205-211. 3. Liberson WT, Homquest HJ, Scot D, Dow M. Functional electrotherapy: Stimulation of the peroneal nerve synchronized with the swing phase of the gait of hemiplegic patients. Arch Phys Med Rehabil 1961; 42:101-105. 4. Burridge JH, Taylor PN, Hagan SA, Wood DE, Swain ID. The effects of common peroneal stimulation on the effort and speed of walking: A randomized controlled trial with chronic hemiplegic patients. Clin Rehabil 1997;11:201-210. 5. Stein RB, Chong S, Everaert DG, et al. A multicenter trial of a footdrop stimulator controlled by a tilt sensor. Neurorehabil Neural Repair 2006;20:371-379. 6. Kottink AI, Hermens HJ, Nene AV, et al. A randomized controlled trial of an implantable 2-channel peroneal nerve stimulator on walking
PM&R
7.
8.
9. 10.
11.
12.
13.
14.
15.
speed and activity in poststroke hemiplegia. Arch Phys Med Rehabil 2007;88:971-978. Stein RB, Rolf R, Everaert DG, Bobet J, Chong S. Surface electrical stimulation for foot drop: Control aspects and walking performance. J Automat Control 2008;18:47-52. Sheffler LR, Hennessey MT, Naples GG, Chae J. Peroneal nerve stimulation versus an ankle foot orthosis for correction of footdrop on stroke: Impact on functional ambulation. Neurorehabil Neural Repair 2006; 20:355-360. Sheffler L, Chae J. Neuromuscular electrical stimulation in neurorehabilitation. Muscle Nerve 2007;35:562-590. Cauraugh JH, Naik SK, Hsu WH, Coombes SA, Holt KH. Children with cerebral palsy: A systematic review and meta-analysis on gait and electrical stimulation. Clin Rehab 2010;24:963-978. Durham S, Eve L, Stevens C, Ewins D. Effect of functional electrical stimulation on asymmetries in gait of children with hemiplegic cerebral palsy. Physiotherapy 2004;90:82-90. Johnston TE, Finson RL, McCarthy JJ, Smith BT, Betz RR, Mulcahey MJ. Use of functional electrical stimulation to augment traditional orthopaedic surgery in children with cerebral palsy. J Pediatr Orthop 2004; 24:283-291. Ho CL, Holt KG, Saltzman E, Wagenaar RC. Functional electrical stimulation changes dynamic resources in children with spastic cerebral palsy. Phys Ther 2006;86:987-1000. van der Linden ML, Hazlewood ME, Hillman SJ, Robb JE. Functional electrical stimulation to the dorsiflexors and quadriceps in children with cerebral palsy. Pediatr Phys Ther 2008;20:23-29. Seifart A, Unger M, Burger M. The effect of lower limb functional electrical stimulation on gait of children with cerebral palsy. Pediatr Phys Ther 2009;21:23-30.
Vol. 5, Iss. 6, 2013
509
16. Carmick J. Clinical use of neuromuscular electrical stimulation for children with cerebral palsy, part 1: Lower extremity. Phys Ther 1993;73:505-513. 17. Bertoti SB, Stanger M, Betz RR, Akers J, Maynahon M, Mulcahey MJ. Percutaneous intramuscular function electrical stimulation as an intervention choice for children with cerebral palsy. Pediatr Phys Ther 1997;9:123-127. 18. Comeaux P, Patterson N, Rubin M, Meiner R. Effect of neuromuscular electrical stimulation during gait in children with cerebral palsy. Pediatr Phys Ther 1997;9:103-109. 19. Pierce SR, Laughton CA, Smith BT, Orlin MN, Johnston TE, McCarthy JJ. Direct effect of percutaneous electric stimulation during gait in children with hemiplegic cerebral palsy: A report of 2 cases. Arch Phys Med Rehabil 2004;85:339-343. 20. Prosser LA, Curatalo LA, Alter KE, Damiano DL. Acceptability and potential effectiveness of a foot drop stimulator in children and adolescents with cerebral palsy. Dev Med Child Neurol 2012;54:1044-1049. 21. Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B. Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39:214223. 22. Postans NJ, Granat MH. Effect of functional electrical stimulation, applied during walking, on gait in spastic cerebral palsy. Dev Med Child Neurol 2005;47:46-52. 23. Rushton DN. Function electrical stimulation and rehabilitation: An hypothesis. Med Eng Phys 2003;25:75-78. 24. Laufer Y, Ring H, Sprecher E, Hausdorff JM. Gait in individuals with chronic hemiparesis: One-year follow-up of the effects of a neuroprosthesis that ameliorates foot drop. J Neurol Phys Ther 2009;33:104-110.