Recovery of Sensory and Motor Function After Nerve Repair

Recovery of Sensory and Motor Function After Nerve Repair A Rationale for Evaluation Birgitta Rosen, OT MSc

Department of Hand Surgery University Hospital, Lund University Malmo, Sweden

valuating hand function after nerve repair

E is associated with considerable problems. The outcome is influenced by many factors that de-

pend on cellular and biochemical mechanisms in the peripheral as well as in the central nervous system (CNS). The assessment procedure is a complex process whereby adequate measurements of sensory and motor functions, separately and integrated, have to be defined and quantified. 1 We need valid and reliable tests and measurement instruments for several purposes: to support clinical diagnoses, to evaluate and compare surgical repair techniques, to document progress during rehabilitation, to give feedback to the patient and therapist during sensory re-education, and to evaluate disability after injury. The existing systems for describing and scoring recovery following nerve repair are~unsatisfactory.2A system suggested by the British Medical Research Council (MRC) describes increasing qualities of sensory function from SO to 54. 3 However, the system is based on subjective findings, and the nonstandardized data is vague. MacKinnon and Dellon introduce 2PD (static and moving) as an additional factor. 4 The two-point disCorrespondence and reprint request to Birgitta Rosen, Department of Hand Surgery, University Hospital, Lund University, 5-205 02 Malmo, Sweden.

ABSTRACT: In order to identify an effective· test for evaluating the results of nerve repair, 25 patients, age 10-53 years (mean 27 years), were evaluated two to five years after median or ulnar nerve repair at the distal forearm level. The initial assumption was that evaluation after nerve repair should reflect four aspects of recovery: reinnervation, tactile gnosis, integrated sensory and motor functions, and pain or discomfort. The evaluation included a number of assessment methods addressing these aspects. Attention was paid to the usefulness of the tests with reference to their relevance for assessing hand functions. Clinical utility and possibilities for standardization and quantification of the results were considered important. Statistical analysis showed no correlations between the results obtained in clinical tests for reinnervation and the results from neurophysiologic examination. Grip strength and cold intolerance together accounted for a significant 51 % of the variance in activities of daily living (ADL) capacity. Tactile gnosis correlated weakly with ADL capacity and strongly with age. Based on these findings, the following design for evaluating the result after median and ulnar nerve repair is suggested. To assess reinnervation: Semmes-Weinstein monofilaments and manual muscle-testing; to assess tactile gnosis: classic 2PD and a test with the features of the used shape identification test; to assess integrated functions: selected parts of Sollerman's grip test and grip-strength test with Jamar dynamometer; to quantify pain and discomfort: a four-ranked scale for grading perceived problems from cold intolerance and hypersensitivity. J HAND THER 9:315-327,1996.

crimination test is also poorly standardized and rarely reaches measurable values in adults, so this classification also has drawbacks. According to Omer,s terms like poor, fair, good and excellent can be correlated to the subjective levels in the MRC system. It is possible to identify four key factors for the recovery of hand function. Ultimately expressed in terms of the ability to carry out activities of daily living (ADL), they can be identified as follows: the structural and functional status of peripheral sensoryand motor components, the basis for perceiving tactile stimuli; tactile gnosis, the ability to interpret the new sensory input to the brain, based on tactile stimuli; the integrated sensory and motor functions, "what the hand can do"; and the degree of pain or discomfort in terms of hyperesthesia and cold intolerance. Today we are confronted with a wide variety of tests addressing this spectrum of functions. This study was designed to identify an optimal test battery to address recovery of nerve function with special reference to these four key factors. Special interest was paid to the possible standardization of the tests as well as to their clinical utility (e.g., their costs in terms of time and acceptance by the patients). The primary objective in the evaluation process is to demonstrate regeneration of the nerve and October-December 1996

315

reinnervation of muscles and cutaneous receptors. 1 Among tests reflecting reinnervation of peripheral targets (i.e., "potential to function"6) are neurophysiologic examinations as well as tests for perception of touch, pressure, and vibrationy-9 A second objective is to demonstrate the ability to interpret the new sensory input (i.e., tactile gnosis10), which requires combined physiologic processes in the peripheral as well as the CNS. This unique discriminatory ability to recognize shapes, textures, and objects without seeing them is often restored completely in children but rarely in adults. n - 13 The cortical functional reorganization, occurring after nerve repair in primates/ 4 - 16 indicates that CNS factors may playa key role for recovery of the tactile functions of the hand after nerve repair. Tactile gnosis can be demonstrated by sensory discriminatory tests, such as the two-point discrimination test,17,18 object identification,19 localization of touch/o and the Shape identification testyl The third objective is to assess the skills requiring integrated and interacting sensory and motor functions of the hand 1o,22,23 that can be expressed as dexterity, grip strength, and ultimately as ADL capacity. The fourth objective is to quantify the degree of pain and discomfort in terms of hypersensitivity (discomfort or irritability in response to normal tactile stimulation) and cold intolerance (pain or discomfort in response to normal exposure to indoor and outdoor temperatures), phenomena frequently seen after nerve repair that often hinder ADL. In the present study, an optimal test battery is suggested for assessing recovery of nerve function, taking into account the critical sensory and motor functions of the hand with reference to peripheral as well as central nervous mechanisms.

MATERIAL AND METHODS The study included 21 male and 4 female patients. Fifteen patients were operated on for complete median nerve transection, and ten for complete ulnar nerve transection at the distal forearm level. Mean age was 30.9 years (range 10-53) and 21.5 years (range 11-43) for median and ulnar nerve transections, respectively. The dominant hand was injured in 13 of the cases. Mean time since surgery was three years (range 2-5). In 21 patients the nerve was sutured with conventional suture techniques. 1 In four cases a tub,ulization technique was used. 24 The longest delay between injury and repair was two weeks. The patients underwent assessment of hand function with an extensive battery of tests covering peripheral sensory and motor reinnervation, tactile gnosis, and integrated sensory and motor function as well as a quantification of hypersensitivity and cold intolerance. All tests were carried out during one day (approximately six hours with breaks) in the same order: reinnervation and tactile gnosis tests; neurophysiologic examination; and integrated sensory / motor tests, strength measurement, and 316

JOURNAL OF HAND THERAPY

questionnaire in a quiet testing environment. The neurophysiologic examination was conducted at the Department of Clinical Neurophysiology, University Hospital, Malmo. The tactilometry assessment was performed by a laboratory assistant experienced in the testing procedure. All other tests were carried out by one occupational therapist (the author) with long experience in the testing procedures. For tests requiring exclusion of vision, the examined hand was kept behind a screen and fully supported in sensory reinnervation tests. These tests were also initially demonstrated on the uninjured hand. Normative data were available only for a few of the tests. These specific tests were performed only on the injured hand. For the remaining tests, the noninjured hand was used as a control.

Clinical Tests Tests Addressing Sensory Function: 1. Perception of Touch/Vibration The Semmes-Weinstein monofilaments (minikit) were used according to the procedure described by Bell-Krotoski.8 A 0-to-5 scoring system was used to r~resent the functional interpretation of the test. 8 The scoring scheme took into account the fact that some patients might have been unable to perceive the monofilament marked 6.65, thus getting an "untestable" result. The scores were interpreted as follows: • 0 = untestable • 1 (filament marking 6.65) = perception of deep pressure • 2 (filament marking 4.56) = loss of protective sensation • 3 (filament marking 4.31) = diminished protective sensation • 4 (filament marking 3.61) = diminished perception of light touch • 5 (filament marking 2.83) = normal perception of touch and pre~su.re The findings were mapped (Fig. 1) and totaled, and the percentage of maximum score was calculated for median (maximum score: 5 X 11 zones = 55) or ulnar (maximum score: 5 X 6 zones = 30) areas, respectively. Statistical analysis (Spearman rank correlation) showed that the score from the distal phalanx of digit II or V representing true median- or ulnar-innervated areas correlated strongly with the result from complete median or ulnar nerve innervated areas, respectively (rs 0.91, p < 0.0001). Therefore, the score from the distal phalanx was used. The light-and-heavy moving and the constant touch and vibration (30 and 256 Hz) tests were used according to the procedure established by Dellon. 7 With the examined hand fully supported, moving and constant touch were tested using the examiner's middle finger to stroke and press.

FIGURE 1. Division in zones for median and ulnar nerve used in Semmes- Weinstein monofilament test, Dellon's test for light and heavy moving and constant touch and vibration, and for localization test.

"Light" and "heavy" refer to the intensity of pressure applied. Vibration was tested with 30-Hz and 256-Hz tuning forks struck against a surface; then one prong end was applied to the surface being tested. Testing was performed proximal to distal along the dysfunctioning area. The patient indicated positive response by saying "feeling." The results were quantified by dividing the hand into six levels, proximal to distal (levels 1-3 in palm and levels 4-6 in finger; first phalanx of thumb = level 2, and second phalanx of thumb = level 3) (Fig. 1). The most distal level for positive response of each stimulus was noted. Tactilometry was performed according to Lundborg9 for assessment of vibration perception on a multifrequency basis. A computerized tactilometer was used; the digit to be examined (distal phalanx of digit II for median nerves and distal phalanx of digit V for ulnar nerves) rested on a vibrating probe. The patient indicated a positive response by pressing a button with the uninjured hand when the multifrequency vibrations were perceived during the test session. A specific sensibility index for perception of vibration (normal ~ 0.8)/6 which expresses the ratio between the integrated surfaces under the test curve and the age-matched control-curve, was used as a measurement of vibrotactile sense. ,

pointing to the actual spot being touched. Localization of constant touch was tested by using the finest Senunes-Weinstein monofilament the patient could perceive in each zone of the dysfunctional area. For moving touch, the examiner's finger was used. One point was given for each correct answer. For comparison of median and ulnar nerve injuries, the percentage of correct answers was calculated by dividing the total score by the relevant number of zones. The static 2PD (s2PD) test was performed according to Moberg?7 The examined hand was fully supported, and the pressure applied was just enough to initiate blanching of the skin. The instrument used was the Dellon Discriminator. One or two points were applied randomly in a longitudinal direction on the distal phalanx of digit II or digit V, representing true median- or ulnar-innervated areas. Seven out of ten responses must be correct for scoring. To shorten the test and to avoid fatigue at the fingertip,l1 the distances tested were limited to 15 mm, 10 mm, and 6 mm, representing the limits for "normal" and "not testable," with one distance in the middle. Since some patients might have been unable to differentiate between one or two stimuli at 15 nun (thus getting a result of ~16 mm, or "not testable,"), the author used the following scoring scheme: 0 = ~16 nun, 1 = 15 mm, 2 = 10 mm, 3 = $6 nun. The moving 2PD (m2PD) test was performed according to Dellon. 18 The Dellon Discriminator was moved proximally to distally on the distal phalanx, and the pressure used was just light enough for the subject to perceive the stimulus. Otherwise, the test was performed in the same manner as the s2PD test, and the rationale for scoring was similar. Scoring: 0 = ~10 mm, 1 = 9 nun, 2 = 6 mm, 3 = $3 mm. In the shape-identification test/· 21 ,28 the patient was instructed to identify the shape of 24 metal objects without looking at them (Fig. 2). The objects were variably sized (diameters varying from 7-20 mm), of six different shapes and randomly positioned on a dumbbell. A ~emplate with each shape

Tactile Gnosis

Localization of constant touch and moving touch was determined according to the methods described by Callahan. 20 The hand was divided into 11 zones of dysfunction for median injuries and six zones for ulnar injuries (Fig. 1). One zone at a time in the area of dysfunction was touched. The patient was instructed to identify the place of the touch by

FIGURE 2. Shape-identification testY! The test subject is trying to identify the shape of 24 randomly positioned and variably sized objects of six different shapes without looking at them. October-December 1996

317

marked with a capital letter was positioned in front of the patient. Identification was performed with the thumb, index, and third fingers for median nerves and with the fifth finger for ulnar nerves. To avoid using unaffected areas of the hand, a thick rubber glove was used to expose the relevant fingers. The median-injured patients were instructed not to use the lateral aspects of the thumb with possible radial nerve sensory innervation. Before starting the test, the patient was allowed a glance at the dumbbell to understand the random distribution of the various sized objects and was then instructed to identify the shape of one object at a time. The objects were exposed in a standardized order: side "one" of the dumbbell to the uninjured hand, side "two" to the injured hand, side "three" to the uninjured hand, side "four" to the injured hand, side "two" to the uninjured hand, and so on until all the objects were exposed. Identification was not timed. A patient who felt that an object was ~mpossible to identify was told to go to the next one. One point was given for each correct answer. The object identification test/ 9 because it requires active manipulation, was carried out only on patients with median-nerve injuries. Twenty objects were presented randomly to the patient's gloved hand, exposing digits I, II and III, for identification. The objects were chosen to represent different shapes, textures, sizes (range of diameter 1-5 em), and weights and to be well-known, everyday objects. A period of 30 seconds was allowed for recognition of each item. The number of correct answers was noted.

Tests Addressing Motor Function Muscle activity was examined by the Intrinsicmeter dynamometer according to the principles established by Mannerfelt. 29 This device is based on a spring technique; two steel plates are pressed together, and the movement is recorded by a precision meter (0.25-6.6 kg). The examination is done according to the breaking force technique. In testing abduction of digit II, the instrument was held by the examiner in one hand against digit II at the proximal interphalangeal joint level, with the digit in maximal abduction, while the examiner's other hand supported the ulnar part of the patient's pronated hand. The patient was then instructed to resist when the examiner pressed the instrument in the ulnar direction. The instrument was read when digit II reached digit III. Muscles tested were those in median- (palmar abduction digit I) or ulnar-inn,ervated (abduction of digit II and digit V) movements. The results were expressed as a percentage of the performance compared with the uninjured hand. For patients who had ulnar nerve repair, a mean value was calculated between the abduction of digits II and V.

Tests Addressing Integrated Sensory and Motor Functions Because Moberg's pick-up tese o requires active manipulation, it was carried out only on the pa318

JOURNAL OF HAND THERAPY

tients with median-nerve injuries. Twelve objects (coin, button, safety pin, screw, paper clip, key, tube cap, eraser, piece of cotton wool, piece of foam rubber, match, nail) were used. The patients were instructed to pick up each object under three different circumstances: first, while looking at the object; second, blindfolded; and third, blindfolded and trying to identify the objects. For emphasis on the sensory part of the test, the patient used a glove exposing digits I, II, and III. The average time used in three trials was calculated, and the percent of the performance compared to the uninjured hand was noted. The number of correctly identified objects was noted, as well. Sollerman's grip teseOA7 evaluates the quality of basic grip types. The test consists of 20 different tasks that replicate the main hand grips used in ADL. Each subtest is scored depending on the choice and quality of the hand grip and on the patient's difficulty in performing the task. The test was performed in the standardized procedure, and the score of the injured hand was noted. An examination of grip strength using the Jamar dynamometer according to the principles established by Mathiowetz31 ,32 was performed in the standardized procedure. Three trials with each hand were carried out, and the mean value was calculated. The results were expressed as a percentage of the performance compared with the uninjured hand. When designing the present study, a standardized ADL instrument corresponding to the objectives was not available. A questionnaire was constructed and designed to reflect the patient's experience of his or her capacity to perform different activities. It was not designed to be a test of the capacity to perform tasks with the injured hand, but it was also a very subjective view of how the patient experienced the way he or she performed everyday activities. The questionnaire focused on 28 specific activities of different domains (personal care, home maintenance, communication, leisure, work or school) (Table 1). The patient could choose among five alt~rnatives for each answer and could also add activities. Quantification was made as follows: X = nonapplicable: do not normally perform the activity; 3 = can perform the activity easily; 2 = can perform the activity with some difficulty; 1 = can perform the activity with great difficulty; 0 = cannot perform the activity. The total score was divided into the number of applicable activities, resulting in an ADL index (maximum 3.0). To validate the questionnaire, the patients were asked to estimate how much the nerve injury influenced their daily activities by using a visual analog scale (VAS).33.34 The end points of the scale (10 em, horizontally oriented without markings) represented fIno influence on ADL" and "greatest possible influence on ADL." Scoring of the VAS was done by measuring the centimeters from the low end of the scale (no influence) to the subject's mark,33 Statistical analysis (Spearman-rank correla-

TABLE 1.

Personal Care Manipulating cutlery / glass Washing Teeth-brushing Hair-care Shave/apply make-up Nail-care Toilette Dressing

Home Make the bed Cleaning Washing laundry Ironing Sewing (basic) Cooking Washing up Set the table/serve Purchasing Gardening Maintenance/repairing

ADL Questionnaire

Miscellaneous Manipulating keys Writing Telephoning Manipulating book/paper Driving car Bicycling Lifting/carrying

tion) showed significant good correlation (rs 0.69, p

= 0.0007) between estimation on VAS and the ADL

index calculated from the ADL questionnaire.

Tests Addressing Cold Intolerance and Hypersensitivity The examiner would stroke the dysfunctional area and question the patient about hypersensitivity and cold intolerance in ADL. The patient would then select one of the following descriptions: 1 = none or minor; 2 = moderate; 3 = disturbing; 4 = hinders function.

Neurophysiological Tests Electroneurography Two needle electrodes (Dentec type 13L61) were placed close to the nerve and proximal to the injury level with an interelectrode distance of 2 cm. The position was adjusted to a minimal threshold for evoking a response from the target muscle (APB or Abd digit V), recorded with an inserted concentric electromyogram needle (Nicolet Viking III).35 The motor conduction time (ms) was assessed by a ~l.1pramaximal stimulation of the nerve. The conduction time reflects diameter and myelinization of the nerve fibres. The conduction velocity (m/s) in the fastest sensory fibres was assessed by supramaximal stimulation of the fingers (ring electrodes) and recording from the needle electrodes. The amplitude (/-LV) recorded from the initial positive to the following negative peak of the sensory nerve action potential was used as a measure of the population of functioning fibers. For the median nerve, the results from digits I, II, and III were totaled and divided in three. For the ulnar nerve, the result from digit V was used.

Electromyography Electromyographic recording from the muscles during maximal voluntary contraction was used to estimate the amount of voluntary activity. An arbitrary scoring of maximal voluntary activity displayed on the screen at slow sweep speed and visually inspected was used for quantification. The scoring ranged from -6 (zero activity) to 0 (normal activity).

Leisure The patient lists detailed activities or summarizes leisureactivities

Work/School The patient lists detailed activities or summarizes work/ school activities

Statistics Spearman rank correlation statistics were initially used to investigate the relationships among single variables. In a second step, multiple regression analysis was used to analyze the variables when interacting. A p-value of :50.05 was considered significant. A Mann Whitney U-test was performed to determine if the test results were influenced by which nerve was affected.

Correlation Statistics The well-known relative influence of age on the result after nerve repair was first examined on all parameters with Spearman rank correlation. The neurophysiologic sensory and motor examination (sensory amplitude, sensory conduction velocity, voluntary motor activity, motor conduction time) was thought to contribute the most objective parameters for reinnervation (dependent variables) and was correlated to the clinical tests for sensory and motor reinnervation, respectively. Correlation to hypersensitivity and cold intolerance were also examined. The ADL index, based on the patient's own opinion of his or her capacity was considered the ultimate outcome. It was therefore considered the dependent functional variable and was correlated to the functional parameters (tactile gnosis and integrated sensory/motor functions) and to hypersensitivity and cold intolerance.

Multiple Regression Analysis Multiple regression analysis was used in a second step to investigate the strength of the influence of the significantly correlating independent variables on results from neurophysiologic examination and the ADL questionnaire, respectively. The number of patients permitted a regression model that included only four variables at a time. Age was corrected for when appropriate.

Clinical Considerations The tests were reviewed according to how well October-December 1996

319

TABLE 2.

Correlations Between Age and All Other Parameters

Test

r,

Object identification (score: 0-20) -0.90 Number of correct identifications Mo-0.86 berg's Pick-up test (score: 0-12) m2PD (2:10 mm or measureable) s2PD(2:16 mm or measureable) Perception of touch/pressure Semmes-0.55 Weinstein monofilaments (score: 0-5) -0.50 Shape identification test (score: 0-24) Moberg's Pick-up test, with vision (time:percent of uninjured hand) 0.65 Localization of moving touch (percent of correct identified zones) -0.47 -0.47 Sensory nerve conduction (m/s) Moberg's Pick-up test, without vision (time:percent of uninjured hand) 0.50 Motor nerve conduction time (ms) 0.45 -0.38 Sollerman's grip test (score: 0-80) Gripstrength, Jamar dynamometer (kg: -0.38 percent of uninjured hand) Perception of vibrations, Tactilometry . -0.34 (Index: normal 2: 0.80) Hypersensitivity (perceived problems: 1-4) 0.29 Localization of constant touch (percent of correct identified zones) -0.29 Moberg's Pick-up test without vision + identification (time:percent of uninjured hand) 0.37 Cold intolerance (perceived problems: 1-4) 0.24 Motor voluntary activity (-6-0) -0.26 -0.21 Sensory amplitude (/-Lv) -0.19 ADL-index (Index: 0-3) Muscle strength, Intrinsicmeter (percent 0.08 of uninjured hand)

0.001

n 14

0.001 0.001* 0.005*

15 25 25

0.007 0.01

25 25

0.01

15

0.02 0.03

25 22

0.05 0.05 0.06

15 20 25

0.07

24

0.09

24

0.15

25

0.16

25

0.18

15

0.23 0.23 0.33 0.33

25 22 22 25

0.69

24

p

Spearman rank correlation. *Mann-Whitney V-test was used with a dichotomized scale due to skewed distribution of the results.

they corresponded to the standardization norms described by Fess,38 and how useful the test instruments were in specific clinical situations. Is the test easy to administer? Does the test take less than 20 minutes to perform? Is the test easily accepted by the patients? Is the test applicable to both medianand ulnar-nerve injuries?

RESULTS Influence of Age, Hand Dominance, and Injured Nerve Low age demonstrated significant relationship with sensory and motor nerve conduction as well as with the perception of touch and pressure assessed with Semmes-Weinstein monofilaments. There were also significant correlations with most of the tactile gnosis tests (Table 2). Whether the dominant hand was injured had no significant influence on the outcome of the ADL index. The Mann-Whitney V-test indicated that patients with ulnar-nerve injuries performed significantly (p s 0.05) better in most of the reinnervation tests (sensory and motor nerve conduction p = 0.03 and 0.01, respectively; Semmes-Weinstein monofil320

JOURNAL OF HAND THERAPY

ament test p = 0.007, and tactilometry p = 0.004), in the s2PD test (p = 0.02), and in the Sollerman grip test (p = 0.0002).

Reinnervation The results of the sensory neurophysiologic examinations (conduction velocity, sensory amplitude) and the clinical tests for sensory reinnervation (Semmes-Weinstein monofilaments, tactilometry) showed no significant correlations. Neither hypersensitivity nor cold intolerance was significantly related to the sensory neurophysiologic examinations. The results of Dellon's tests for perception of moving and constant touch and vibration could not be used in the statistical analysis due to the skewed distribution of the results (Tables 3A,

3B).

The results from the clinical muscle tests (strength in palmar abduction of digit I or mean of strength in abduction of digits II and V) did not correlate with the results from motor neurophysiologic examinations (motor conduction time, electromyographic recording during voluntary contraction). Initially, the result from the clinical muscle test correlated significantly with the motor conduction time. After correcting for age in multiple regression analysis, however, the relationship turned out to be too weak for significance.

Tactile Gnosis and Integrated Functions The final functional outcome (dependent variable) was considered to be the ADL capacity expressed as an ADL index. The initial correlation analysis demonstrated significant correlations to decreased grip strength, cold intolerance, and m2PD. Stepwise multiple regression analysis demonstrated that grip strength entered the statistical model first, explaining 36% (R2 = 0.36) of the variance in the ADL index, followed by cold intolerance, explaining a further 15% (R2 = 0.15). These two variables together explained 51% of the variance of the ADL index. The influence of m2PD turned out to be too weak when interacting with grip strength and cold intolerance.

Clinical Considerations Table 4 demonstrates that, among the instruments used, only the Semmes-Weinstein monofilaments and the Jamar dynamometer fulfill all the requirements for standardization and have all the specific clinical utility features considered important.

DISCUSSION The Ideal Test: What are the Requirements? The assessment should demonstrate the extent of peripheral reinnervation: i.e., the presence or

nonpresence ofaxons in peripheral targets as well as the level of functional sensibility in terms of tactile gnosis and integrated sensory and motor function. The skin's highly specific receptor system puts extremely high demands on the test instrumentation; this level of specificity, in fact, does not exist today. All hand-held instruments produce unwanted stimuli, and the receptors will respond to any mechanical stimuli. 36,37 To be truly functional, a test should reflect both the physiologic and the psychologic factors influencing the ultimate result. Moreover, a good test should allow its results to be quantified, and it should be comprehensible and easy to perform in a standardized way. It should not tire the patient or be painful, nor should it be too time consuming or expensive. The optimal test should also be applicable to both median- and ulnar-nerve injuries, and it should give the patient and therapist guidance in the rehabilitation process. To be used as a standardized test, an instrument should have documentation confirming its purpose, validity, and reliability. The documentation should also provide a detailed· description, normative data, and instructions for use. 38

Tests Addressing Reinnervation The respective roles of neurophysiologic and clinical examinations for addressing the result after nerve repair is an important issue. From a clinical point of view, the neurophysiologic examination is time consuming, costly, and unpleasant for the patients. It is therefore not used routinely after nerve repair. There were no significant correlations between data obtained in neurophysiologic and clinical tests in the present study, and it seems that clinical examination is sufficient in most instances. Clinically, the Semmes-Weinstein monofilament kit remains a reliable and easily administered instrument. It is also one of the few clinical tests that fulfill all the requirements for a standardized test. 37,39 Tactilometry indicated a significant relationship with the monofilament test (r s 0.56, p = 0.007). It is not a widely used instrument and does not yet fulfill all standardization criteria. The examination of perception of touch and vibration according to Dellon did not show any sensitivity or specificity in this group of patients. It is probably a more sensitive tool in the early phases of regeneration, although the lack of standardization remains a problem. The roughness of all current instruments compared with the delicate receptor system they are supposed to test supports the view that one test instrument should suffice for clinical tests of sensory reinnervation. The optimal instrument today for this purpose is the Semmes-Weinstein monofilament kit. Assessing muscle function using the Intrinsicmeter in these patients is difficult due to the extremely small forces. The instrument is difficult to handle and read. It is also very expensive. Manual muscle testing, MRC Muscle Power Grading 0_5/,40 although not used in this study, is probably the simplest and most appropriate

measurement for this purpose, and recent studies show good reliability in testing intrinsic muscles. 40 . The author believes that the significant differences in test results for reinnervation and s2PD between median- and ulnar-nerve injured patients result from the lower mean age for the ulnar-nerve group (21.5 years vs 30.9 years in the median-nerve group).

Tests Addressing Tactile Gnosis None of the results from the tactile gnosis tests was significantly related to ADL capacity. Most findings correlated significantly with age. We can therefore conclude that adults compensate for the sensory deficit to a large extent and that the very young regain much due to their superior brain plasticity. Normally, each finger is projected as a band in the somatosensory cortex of the brain. The frequent reinnervation of incorrect peripheral targets after nerve repair results in a cortical functional reorganization and a new projective pattern of the hand in the brain. It may be said that the hand speaks to the brain in a new language. 41 Recent studies demonstrate that specific cognitive mechanisms may play an important role in this context if the age factor and degree of reinnervation are taken into account. 28,42 The capacity to recognize shapes, textures, and structures without seeing them is often lost after nerve repair. However this disability might be compensated for by a variety of compensatory strategies in adults. The patients' descriptions of the strange feeling in the hand, though, give evidence of a disabling hindrance in communication with the environment, a subtle handicap not reflected in concrete ADL assessment$. This handicap is important to consider in the evaluation. Documented tactile gnosis also constitutes important feedback for patients participating in sensory re-education programs. The two-point discrjmination test is one of the most difficult tests to perform in a consistent way. When performed in accordance with Moberg's directions, with just enough pressure to blanch the skin, 2PD is hardly ever measurable in adults after nerve repair, resulting in skewed distributed and uncertain figures for statistical analysis (Table 3). Moberg, who strongly advocated the test, stated that it puts very high demands on exactness, concentration, and cooperation between patient and examiner. IO,22 It is traditionally seen as a receptor density test, but the apparent components of central interpretation make it a tactile gnosis test. It may to some extent express functional sensibility/2,43,44 but the lack of standardization and the number of uncontrollable factors in the performance, casts doubts on its value. However, the ingenious simplicity of the method and its worldwide use make it hard to reject this test, despite the lack of standardization. Just as we only need one accurate handheld instrument for sensory reinnervaOctober-December 1996

321

median

50

2

2

5

5

m

m

m

m

m

f

m

m

m

m

m

m

m

m

m

m

f

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

5

m

7

2

2

2

ulnar

ulnar

15

11

ulnar

median

18

2

43

median

19

2

2

median

47

ulnar

ulnar

10

19

ulnar

32

ulnar

ulnar

ulnar

ulnar

median

28

11

26

30

median

median

10

34

median

median

45

21

20

2

2

5

5

2

4

4

2

2

m

6

median

median

15

3

m

5

53

median

44

m

3

3

median

15

4

4

median

36

3

m

2

median

26

3

m

1

Nerve

Time Since Surgery, Pat nr Sex Years Age

1.3 1.0 3.0

6.4 6.8 5.0 4.5 3.3

-1

-3 -3 -3 -3

-4

-2

-2

-3

-3

-1

8.7

5.0

6.0

4.5

5.0

2.5

4.2

o

-4

1.3

5.6

-2

27.3 31

0.7

49

33

31.7

6/6/6/6/6/6 6/6/6/6/6/6 6/6/6/6/6/6 6/6/6/6/6/6 6/6/6/6/6/6

2.83 3.61 3.61 3.61 2.83 2.83

0.42 0.77 0.89 0.71

0.81

0.83

6/6/6/6/6/6

6/6/6/6/6/6

0.78

3.61

6/6/6/6/6/6

3.61

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

2.83 3.61

6/6/6/6/6/6

2.83

6/6/4/3/3/2

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

6/6/6/6/6/6

4.31 0.64

0.66

0.83

37 52

0.67

50

0.90

42

4.56

3.61

0.48 0.73

4.31

2.83

4.31

4.31

6.65

4.31

4.56

6/6/6/6/6/6

4.31

0.54

0.75

0.76

0.69

0.11

0.55

0.42

6/6/6/6/6/6

6/6/6/6/6/6

4.31

4.31

0.40

0.73

6/6/6/6/6/6

3.61

0.68

49

35

35.6

37.3

37

30

20

36.6

37

31

1.17

2.0

2.0

0.87

2.0

3.0

3.0

2.0

6.1

3.9

0.33

1.0

4.1

5.4

-2

8.6

-3

4.6

-2 7.9

5.8

-2

-3

6.4

-4

48

38

2.6

5.5

-2

0.37

34

4.0

5.9

94

82

63

84

75

72

77

65

37

65

85

65

61

69

49/37

48/42

29/31

43/52

43/39

10/33

9/13

20/63

30/SO

25/1

Tuning Fork 30 Herz/Heavy Strength, Strength Moving Touch/Heavy ConPalmar Abduction stant Touch/Light Moving Abduction Dig II/V, Tactilometry, Semmes-Weinstein Touch/Light Constant Dig I, % of % of Sensibility Monofilaments Touch/Tuning Fork 256 Uninjured Uninjured Index Dig II or V Hand Hand Herz, Level 0-6 in Hand

Clinical Tests for Perception of Touch/Pressure, Vibration, and Motor Function

Individual Patient Data

Sensory Motor Sensory Conduction Conduction Amplitude, Velocity, Time, ms ....V m/s

-4

Voluntary Motor Activity -6-0

Neurophysiologic Examination

TABLE 3A.

Tactile Gnosis

22

16 18

~16/~1O

~16/~1O

~16/~10

~16/~1O

~16/~10

~16/~10

$6/6

~16/~10

~16/~10

$6/6

~16/~10

10/9

~16/6

91/55

91/73

91/64

55/36

100/82

82/91

100/91

82/55

100/18

91/83

91/50

50/33

83/17

100/100

83/27

83/33

45/33

100/73

100/64

100/67

100/17

100/67

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

10/6

15/9

~16/~1O

~16/6

10/3

~16/~10

10/6

~16/~1O

~16/~10

20

~16/~1O

100/100

3

12

17

18

22

22

12

14

12

10

108/302/302

150/371/371

77/10

80/12

80/12

76/8

75/7

79/11

76/8

73/7

79/12

80/12

79/11

77/12

76/9

72/6

78/10

72/4

73/6

71/4

67/5

76/8

75/8

73/6

72/4

74/7

15

140/375/215

127/258/603

192/338/697

100/118/128

138/278/361

140/263/531

200/492/-

177/300/556

100/140/189

111/154/332

117/168/400

136/583/727

140/320/343

80/12

8

9

9

12

10

11

7

11

9

11

9

12

Sollerman's Grip Test, Score 0-80 (All Tasks)/ 0-12 (Task 4,8,10)

20

7

13

19

5

6

7

6

13

13

3

7

20

21

o

1

13 3

16

10

3

11

24

8

16

9

~16/6

64/73

2

21

~16/~10

100/27

1

Moberg's Pick-up Test with Vision/Without Vision/Without Vision + Identification (Sec.) % of Uninjured Hand

72

81

106

99

94

100

108

87

79

80

72

93

84

68

64

100

86

58

59

60

66

74

69

74

3.00

2.78

2.96

2.88

2.93

2.90

3.00

2.93

2.86

2.83

2.30

2.96

2.54

1.93

2.24

3.00

2.86

2.25

2.93

2.79

2.40

2.56

2.44

2.70

2.57

1

2

3

3

2

1

6

3

1

4

7

1

5

7

5

1

1

6

1

1

6

5

6

4

4

1/1

3/1

1/1

2/1

2/3

2/1

2/1

3/2

1/1

1/3

4/1

1/2

3/1

4/3

1/2

2/1

3/1

3/4

2/1

3/4

3/1

2/1

3/1

3/2

2/1

Grip Strength (Jamar), Cold Intolerance/ % of ADL VAS, Hypersensitivity, Uninjured Index, Estimation Perceived Problems, 1-4 Hand 0-3 of ADL

Integrated Sensory/Motor Functions

Individual Patient Data

Localization of Moving Touch/ Number of CorConstant Touch, rect Identified % of Correct Shape Object Items in MoPat Identified s2PD/m2PD, Identification, Identification, berg's Pick-up nr Zones mm Score 0-24 Score 0-20 Test, Score 0-12

TABLE 3B.

TABLE 4.

Semmes-Weinstein monofilaments Jamar dynamometer Shape identification test Localization of touch SolIerman's grip test Moberg's pick-up test with vision Moberg's pick-up test without vision Perception of touch/vibration according to DelIon 2PD Intrinsicmeter Object identification Moberg's pick-up test without vision + identfication Neurophysiological examination Tactilometry ADL index

Correspondence to Standardization Norms and Clinical Considerations

Fulfils Standardization Nonns"

Takes 20 Min or Less to Perfonn

Easily Accepted by Patients

Applicable to Both Median and Ulnar Nerve Injuries

Easy to Administer

yes

yes

yes

yes

yes

yes no no yes no

yes yes yes no yes

yes yes yes yes yes

yes yes yes yes no

yes yes yes yes yes

no

yes

yes

no

yes

no

yes

yes

yes

no

no no no

yes yes yes

yes yes yes

yes no no

no yes no

yes

no

no

yes

no

'no no

no yes

yes yes

yes yes

no yes

tion, we probably only need one 2PD-the classic 2PD-meticulously performed. The new computerized instruments for the 2PD test were not used in this study. There is no standardized test for localization of touch. The results of this study support previous results45 that moving touch is too easy to localize and constant touch is too hard to localize (Table 3). Moreover, localization exercises are often routine in sensory re-education programs, and a basic rule is that tests never should be used in training. 38 An identification test using real objects is too subjective. An object considered to be everyday by the therapist might not even be known by the patient. This is an instrument best suited for sensory reeducation programs. The shape-identification test indicated high sensitivity and specificity for this group of patients: 100% reached full score with the uninjured hand, and 4% reached full score with the injured hand. Since this test design is fairly new, it has not been evaluated enough to fulfill all standardization norms. Still, this test has qualities desirable in a tactile gnosis test. It is a pure sensory test for central interpretation of tactile input, it is easy to perform in a consistent way, it is applicable to both medianand ulnar-nerve injuries, it can be used when motor function is incomplete, and it contains a component of "active touch" that should be distinguished from "passive touch" or ''being touched."46 In active touch, the patient touches the item to identify, thereby activating an optimal number of receptors, and the proprioceptive information from joints and muscles strengthens the stimulus of the skin. This exploratory way of touching, combined with the other qualities of this test, make it an attractive tactile gnosis test. The definite design needs refining and further investigation. 324

JOURNAL OF HAND THERAPY

Integrated Functions and Hypersensitivity! Cold Intolerance Patients recovering from a nerve repair-median as well as ulnar-often describe themselves as fumbling. A subtle deficit is reflected in reduced sensibility, reduced sudomotor function, and unbalanced intrinsic muscles. Therefore, a test of the integrated sensory and motor functions should contain manipulative elements emphasizing the sensory as well as the motor elements. Sollerman's grip test contains such elements, and it indicated high sensitivity for these patients in three of the 20 tasks (no 4: pick up coins from purses; no 8: pick up nuts from felt-covered surface and put on bolts; no 10: fasten buttons) (Fig. 3). The results from these three tasks correlated strongly with the result of the complete grip test (rs 0.96 (p = <0.0001). One suggestion is to use these three selected tasks in evaluating integrated sensory and motor functions addressing dexterity after nerve repair with the use of pulp pinch, lateral pinch, and tripod pinch. The test fulfills standardization norms in its original performance. 3o•47 It is a time-consuming test, so using only three of the 20 tasks for this patient group would simplify it. There is a significant difference in the Sollerman's grip test results between median- and ulnarnerve injured patients. The author believes that problems with precision grip occurring 2 years or more after repair are more emphasized in mediannerve injured patients. Further investigation is needed. Moberg's pick-up test is the classic test for investigating integrated sensory and motor functions. Its advantages lie in its simplicity and in its clear illustration of deficits to both examiner and patient. The occurrence or nonoccurrence of opponens func-

• =max score Median Task or

Ulnar

(n=lm

(n=l~

1 ••••• ~ ••••••••• ••••••••••

-r~~;ey into

~:~~ 2~~• • • ~.~• • ~ • • • • • • • • • • • ~• •

FIGURE 3. Sollerman's grip test; results of injured hand.

-Open/shut zippers

3 •••••••••••••••

-Pick up coins from purse

~ •••••••••

4~~~~~rn~~~.~~~~~

-Lift wooden cubes

S • • • • • ~ • • • • • • • • • • • • ~~ • • • • •

•••• ~ •••••

.. .....

-Lift iron

6 ••••••••••••••••••• ~ •••••

-~~~~~T~~th

7 • •~ • • • • • • • ~ • • • •

-Put nuts on bolts -Tum off lid of jars

8~~~~~~~~~.~~~~~.~

~••••••••• ~

9 ••••••••••••••••••••••••• 1 0~~1!l~~~~1!l~~1£1~~~1!l • • • • 1£J• • 1!l• • buttons -Cut play-DOh 11••••• ~ ••••• ~ ••• •••••••••• -~:ig~tJ~~i~g 12• • • • • • • • • • • • • • • • • • • • • • • • • -Do up four

-Write with pen

13••••••••••••••• 11........ .• •••••••••.

16................

-i~~~d::J:I~::tI4 -~~~~clip -~~~\et~~~phone

.

15.•••••••••••••• • •••••••••

17• • • • • • • • • • • • • • • • • • • • • • • • • -Pour water fromI8 • • • • • • • • • • • • • • • • • • • • • • • • • purepac -Pour water 19• • • • • • • • • • • • • • • • • • • • • • • • • from jug -Pour water 20• • • 1'• • • • • • • • • • • • • • • • • • • • • from cup -J::-handle

tion in a grip situation reflected in Moberg's Pickup test with vision is also illustrated in the manipulativeelements in Sollerman's grip test. For the sensory elements of the test without vision, there are better tactile gnosis tests. Other tests do not offer the chance to observe compensatory strategies as in the pick-up test without vision. Its drawbacks are that observations are difficult to express in parameters other than time and also the lack of standardization. The influence from sensory input on force control is of great importance. 23 Reduced grip strength, being the motor extreme among the integrated functions, was confirmed in the statistical analysis to be of importance for the patient's opinion of his or her ADL capacity. So was cold intolerance. It is a well-known clinical fact that cold intolerance is an important factor for ADL capacity several years after nerve repair and a common reason for change of work or leisure activities. There were no significant relations between hypersensitivity and ADL capacity, perhaps because hypersensitivity is often a problem in the early phases of rehabilitation. Discomfort and pain are difficult to quantify. The fourranked quantified descriptions of perceived problems from cold intolerance and hypersensitivity

designed for this study were comprehensible to the patients. Several authors emphasize the importance of an ADL reflection in the evaluation after nerve repair. 10,4S,48,49 The ADL instrument used in the present study has not yet been}ested for reliability, but it correlated well with. the patients' estimation, on a visual analog scale, of how much the injury influenced ADL. Such ADL instruments change between cultural areas and are therefore difficult to standardize. Nevertheless, an ADL assessment should always be carried out parallel with the evaluation after nerve repair in order to guide the rehabilitation program.

CONCLUSION On the basis of the results obtained in the present study, from both a scientific and an empirical standpoint, the following test battery design is suggested for routine evaluation after nerve repair (Table 5). For assessment of reinnervation: SemmesWeinstein monofilaments and manual muscle testing; for assessment of tactile gnosis: classic 2PD and a test with the features of the shape-identification October- December 1996

325

TABLE 5.

Reinneroation (Sensory) Semmes-Weinstein monofilament minikit8

Suggested Test Battery Design After Nerve Repair

Reinneroation (Motion) Manual muscle testing 0_540

Tactile Gnosis A test with the features of the shapeidentification test'

The s2PD test

test; For assessment of integrated functions: selected parts of Sollerman's grip test and gripstrength testing with a Jamar dynamometer; for quantification of pain or discomfort: the four descriptions of perceived problems from cold intolerance and hypersensitivity. This test battery is suggested after determining the relative value of some commonly used tests. The optimal tests, however, have yet to be determined. Some of the instruments used and recommended in this study (Table 5) need further development to fulfill all the requirements for standardized tests. Also, methods for documentation and a scoring system for grading the overall result after repair of the median and ulnar nerves should be developed.

7. 8.

9. 10. 11. 12. 13.

Acknowledgments 14. This study was supported by grants from the Swedish Medical Research Council no 5188 and the Swedish Work Environment Fund. Special thanks to Professor Goran Lundborg and Dr Jan Holmberg, Department of Hand Surgery, University Hospital MAS, for reading the manuscript and providing constructive criticism; Professor lngmar Rosen, Department of Clinical Neurophysiology, University Hospital MAS, for discussing the neurophysiologic data; Ingrid Hallberg, for technical assistance (tactilometry); and Jan Ake Nilsson, Department of Statistics and Information Processing, University Hospital MAS, for statistical expert advice.

15. 16.

17. 18.

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326

JOURNAL OF HAND THERAPY

20.

21.

22. 23. 24.

Integrated Sensory and Motor Functions Three selected tasks (nos. 4, 8, 10) from Sollerman's grip test30 Grip-strength test with Jamar dynalmometer12; percentage of performance compared with uninjured hand

Pain or Discomfort Description of perceived problems from cold intolerance: none/minor, moderate, disturbing, hinders function Description of perceived problems from hypersensitivity: none/minor, moderate, disturbing, hinders function

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25. Prince vK, Butler B: Measuring sensory function of the hand in peripheral nerve injuries. Am J Occ Ther 6:385-395, 1967. 26. Lundborg G, Dahlin LB, Lundstrom R, Necking LE, Stromberg T: Vibrotactile function of the hand in compression and vibration-induced neuropathy. Sensibility index-a new measure. Scand J Plast Reconstr Surg Hand Surg 26:275281,1992. 27. Moberg E: Two-point discrimination test a valuable part of hand surgical rehabilitation in tetreplegia. Scand J Rehabil Med 22:127-134,1990. 28. Rosen B, Lundborg G, Dahlin LB, Holmberg J, Karlsson B: Nerve repair: correlation of restitution of functional sensibility with specific cognitive capacities. J Hand Surg 19B: 452-458, 1994. 29. Mannerfelt L: Studies on the hand in ulnar nerve paralysis. Acta Orthop Scand (suppl 87):61-86, 1966. 30. Sollerman C, Ejeskar A: Sollerman hand function test: a standardized method and its use in tetraplegic patients. Scand J Plast Reconstr Surg Hand Surg 29:167-173,1995. 31. Mathiowetz V, Kashman N, Volland G, Weber K, Dowe M, Rogers S: Grip and pinch strength: normative data for adults. Arch Phys Med Rehabil 66:69-74, 1985. 32. Mathiowetz V, Weber K, Volland G, Kashman N: Reliability and validity of grip and pinch strength evaluations. J Hand Surg 9A:222-226, 1984. 33. Gift AG: Visual analog scales: measurement of subjective phenomena. Nurs Res 38:286-288,1989. 34. Wewers ME, Lowe NK: A critical review of visual analogue scales in the measurement of clinical phenomena. Res Nurs Health 13:227-236, 1990. 35. Buchthal F, Rosenfalck A, Behse F: Sensory potentials of normal and diseased nerves. In Dyck PI, Thomas PK, Lambert EH, Bunge R (eds): Perpheral Neuropathy. Philadelphia, Saunders, 1984, pp. 981-1015. 36. Bell-Krotoski JA: Advances in sensibility evaluation. In Mackin EJ, Callahan A (eds): Hand Clinics. Frontiers in

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38.

39. 40.

41. 42. 43. 44. 45. 46. 47. 48. 49.

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327