- Email: [email protected]
Measuring outcome in median nerve injuries
MEASURING
OUTCOME
IN MEDIAN
NERVE
INJURIES
C. JEROSCH-HEROLD
From the Rehabilitation Research Unit, University of Southampton, UK
Assessing the functional outcome of peripheral nerve suture in the hand requires a battery of tests which are valid, reliable and comprehensively evaluate cutaneous sensibility. This study explores the relationship between a battery of sensory tests and the patient’s capacity to perform everyday functional activities. An analysis of the interrelationship between all outcome variables reveals that the tests of sensibility do not predict the patients’ ability to use their hands in everyday activities, thus indicating that patients are able to compensate for sensory deficit through the use of vision and bilateral use of the hands. An assessment of outcome should therefore include an additional measure of performance on daily living tasks. Journal of Hand Surgery (British and European Volume, 1993) 18B: 624-628 METHODS
The assessment of recovery of functional sensibility after peripheral nerve repair to the hand remains a challenge to therapists and surgeons. Therapists are currently faced with a plethora of tests to choose from. Each test is often time-consuming and complex to administer and fatiguing for the patient. While the use of one single test may be attractive, particularly in a busy out-patient setting, such efforts have had to be abandoned in the light of the complexities of sensory neurophysiology. A battery of tests which correlate with neurophysiological parameters and integrated hand function is required to give a valid, reproducible and comprehensive assessment of sensory recovery. Such an assessment tool is an essential prerequisite for evaluating patients for further surgery, documenting progress and planning treatment, and rating compensation cases. While the literature on the validation of outcome measures for peripheral nerve repair is abundant there also still exists a controversy over the correlation between clinical sensory tests and the functional capacity of the injured hand. For example, in seeking to quantify the function of the hand in an objective manner, tests are often standardized to preclude the demonstration of compensatory strategies. Dellon (1981) suggests the taping of the little and ring fingers into the palm when testing integrated hand function for the median nerve, to stop the patient ‘cheating’. Yet if outcome measures seek to determine how well the patient is able to make use of his hands for everyday living then the strategies used to overcome residual deficit also need to be given consideration in an evaluation of outcome. Moreover, functional activities often involve bilateral use of the hands; thus while one hand may move in a much slower and less coordinated manner, both hands may function efficiently (Smith, 1973). A study was designed which sought to determine how best to assess sensory recovery in patients after peripheral nerve repair to the hand. The objectives of the study were two-fold: to compile a battery of tests which together provide a valid, reliable and comprehensive assessment of sensibility, and to establish whether the results from such tests correlate with the patient’s ability to perform activities of daily living.
A correlational design was used to investigate the strength of relationships between tests of sensibility and functional capacity of the hand 2 or more years after surgical repair of the median nerve at the wrist. Subjects acted as their own controls by comparing the results of the sensibility tests in the affected hand with the unaffected hand. Subjects 14 patients who had sustained a partial or complete median nerve lesion at the level of the wrist and who had undergone primary surgical repair at the same centre 2 or more years ago were included in the study. Fibre-end-organ relationships are considered to be sufficiently matured after 2 years for assessment of injuries at the wrist level (Mackel, 1985). Patients who had subsequently developed reflex sympathetic dystrophy or any other impairment affecting sensory-motor function of either upper limb were excluded. The age range was 19 to 61 years with a mean age of 38.1 years. Three patients were female and 11 were male. The average time since repair was 48.1 months (standard deviation 25.5 months). All patients had attended an intensive period of rehabilitation following surgery with the aim of returning to work at 6 to 12 weeks after injury depending on associated injury to the flexor tendons. None of the patients received any formal sensory re-education. Instrumentation A battery of sensory tests was compiled to provide a comprehensive assessment of the patient’s sensory recovery. The standardized method of application and rationale for their choice with reference to the literature is described here. The static two-point discrimination test (S2-PD). This was performed on the patient’s distal phalanges of the thumb, middle and ring fingers using the DellonMackinnon Diskriminator. The final threshold value for 624
MEDIAN
NERVE
625
INJURIES
each digit was determined as the smallest distance at which the patient was able to correctly discriminate seven out of ten random applications of one and two points. This test of spatial discrimination (Moberg, 1958) has been found to correlate with tests of integrated hand function (Moberg, 1962), thus indicating that it is a valid measure of functional sensibility. Subsequent studies however showed that patients with seemingly poor two-point discrimination demonstrate good integrated hand function (Wynn-Parry and Salter, 1976; McQuillan et al, 1970). One suggestion for this paradoxical observation is that the static 2-PD test measures the innervation density of the slowly-adapting receptor population. Active exploratory touch however is mediated by the quickly-adapting receptor population. The moving two-point discrimination test (M2-PD). This has been found to correlate with tests of integrated hand function (Dellon and Kallman, 1983). Dellon (1978) introduced this version of the test which involves moving the callipers over the skin’s surface. As the static and moving 2-PD tests are thought to test different neurophysiological parameters both were included in the assessment battery. Area localization (LOCAL).
This was tested using a modified version of the test used in a study by Marsh (1990) in which the territory of the injured nerve was divided into proximal, middle and distal zones and patients were asked to correctly localize a light moving touch with a cotton wool tip. Marsh (1990) found that most patients obtained very high scores, indicating that the test was possibly too easy. In this study only the distal phalanges were tested and the test rendered more difficult by dividing each phalanx into four zones giving a total of 12 zones for the median nerve distribution in each hand. Each correctly localized stimulus is given a score of 1 and any error 0.
The mod@ed pick-up test (PICKUP). This was used to obtain a measure of integrated hand function. In search of an answer to the question ‘What can the hand actually do?’ Moberg (1958) developed the pick-up test in which the patient is required to pick up small objects and place them in a container with and without vision. In order to standardize the test Dellon (1981) suggests taping the ulnar digits into the palm to avoid inadvertent use of sensorily intact areas. The objects used for this test have been varied and the norms published based on small samples (Wynn-Parry, 1966; Dellon, 1981). The version used by the author included ten small items (key, nut, bolt, nail, 50-pence piece, ten-pence piece, paperclip, safety pin, wing nut and washer). The patient is asked to pick up the ten items one at a time and place them in the container. This is then repeated and timed without vision. The average time of three trials is calculated for each hand.
Object recognition. This was also tested using the same ten items which are placed one at a time into the patient’s hand and the time taken to identify the object (GNOSIS) and the number correctly identified (OBJECTS) are recorded. The patient’s affected and unaffected hands were tested using all five assessments and the final score derived as
affected x10 unaffected A maximum score of 10 indicates normal sensibility. Using the unaffected hand as a control was considered more appropriate as many tests lack normative data and it has been established that hand dominance does not affect the scores in the two-point discrimination test (Louis et al, 1984) and the integrated hand function tests (Marsh 1990). A pilot study on 20 normal subjects was conducted to establish whether hand dominance has an effect on area localisation using a Wilcoxon signed rank test and no significant difference (P < 0.001) was found between left and right hand scores.
Activities of daily living (ADL)
Functional hand evaluations reported in the literature measure function unilaterally. However, patients sustaining injuries to the non-dominant hand would still be able to perform a unilateral task such as writing. Therefore four everyday tasks were selected which are normally performed bilaterally and irrespective of gender. They were: fastening a row of buttons on a reversible tabard, putting toothpaste on a toothbrush, taking a coin out of a purse and opening a jar of coffee. The same standardized items were used and patients were asked to perform each activity as they would normally do. The order of tasks was kept the same for every subject. Video-recordings were taken of each task being carried out for timing and for later analysis of the hand prehension patterns and strategies adopted. Patients were not informed that they were timed.
Statistical methods Univariate analysis of the results was carried out using the MINITAB (version 7.2) statistical package. The data followed a normal distribution with close means and medians, thus the use of parametric tests was considered appropriate. To facilitate the interpretation of how the variables interrelate principal component analysis was performed using the Statistical Package for the Social Sciences (SPSS PC+). This advanced statistical technique identifies a small number of factors or constructs which can be used to represent relationships among many variables.
626
THE JOURNAL OF HAND SURGERY VOL. 18B No. 5 OCTOBER 1993
RESULTS
(r= -0.4710, P=O.O42). In order to establish how all six test variables interrelate a multivariate analysis using principal component analysis with orthogonal rotation was carried out. This statistical technique is suitable for multivariate data and identifies a number of factors which can be used to interpret the relationship between several variables. In this study it was applied to see which tests grouped together to form a factor. The interpretation of what the factors represent is dependent upon which variables load highest on the factor. Two factors were extracted by computational analysis as they account for 87.6% of the variance in all the variables. The factor matrix in Table 3 gives the factor loadings for each of the seven variables. Using factors 1 and 2 to represent the x and y-axis respectively each variable is plotted using their factor loadings as coordinates (Fig 1). Given that factor 1 is determined mostly by the tests of static and moving two-point discrimination, which
The scores for the subject sample in all six sensibility variables and the ADL test are given in Table 1. The Pearson’s correlation coefficients and significance levels between the time taken to complete four tasks of ADL and the five sensibility test scores were calculated. In order to control for the possible effect of age at time of repair, delay between injury and suture, and time since repair, a partial correlation coefficient was computed for all the test variables and is given in Table 2. The negative sign of the correlation coefficient represents a positive relationship as good return of sensibility indicated by a high test score correlates with speed in ADL, that is fewer seconds to complete activities. A significant correlation was detected between ADL and moving 2-PD (r = - 0.5530, P= 0.041) ADL and localization (r = - 0.5700, P= 0.045) and ADL and the number of correctly identified objects in the gnosis test
Table l-The raw results from the subject sample. The scores on the six sensibility variables are calculated as a ratio of the unaffected hand, thus a score of 10 represents a normal score for that test and 0 that the patient is unable to perform the test Case
01 P 02 c 03 c 04 c 05 P 06 C 07 P 08 C 09 P 1oc 11c 12P 13P 14c
Sex
Age
M M F M M M M M M F M M F M
49 59 61 25 60 30 33 19 24 29 41 20 40 44
Delay follow-up Days
Months
0 0 0 1 2 10 0 1 0 0 I 1 0 1
24 56 65 21 26 48 24 25 59 90 32 26 83 89
S2PD
A42PD
Local
Pick-up
Gnosis
Objects
ADL in seconds
10 0 4 7 10 5 10 8 10 8 3 10 10 8
83.15 95.68 65.60 63.82 56.43 51.76 42.48 54.21 51.04 39.87 82.40 51.20 43.80 64.42
Scores as ratio of unaffected hand 3.3 0 0 0 9.3 0 5.6 1.5 9.2 1.0 0 6.7 5.9 0
3.3 0 0 1.1 10 0 6.8 1.9 10 2.5 0 7.9 7.2 0
10 0 1.5 10 10 8.3 10 1.5 9.2 7.5 2.5 8.3 8.0 10
8.24 0 1.1 4 8.8 2.2 8.8 5.5 10 3.5 3.8 8.0 6.4 3.65
1.23 0 2.8 2.6 10 1.0 10 3.3 10 2.2 1.8 8.9 7.3 3.4
C-complete injury. P-partial injury.
Table 2-The partial correlation coefficient and level of significance is given for all seven test variables. Coefficients highlighted in bold represent a significant relationship between two variables even after controlling for possible confounding effects of age, time since injury and delay till repair
M2PD Local Pick-up Gnosis Object ADL
SZPD
MZPD
Local
Pick-up
Gnosis
Object
0.9000 P < 0.001 0.3170 NS 0.8100 P < 0.001 0.7140 P = 0.004 0.5850 P = 0.032 - 0.5240 NS
0.3100 NS 0.7800 P < 0.001 0.6820 P=O.O06 0.5700 P = 0.033 - 0.5530 P = 0.041
0.5160 NS 0.4250 NS 0.7610 P = 0.002 - 0.5700 P = 0.045
0.6830 P < 0.001 0.6970 Pi 0.001 - 0.4330 NS
0.6000 P = 0.007 -0.3690 NS
- 0.4710 P = 0.042
NB n = 14 for all correlation coefficients.
MEDIAN
NERVE
INJURIES
Table 3-The two factors and their loadings for each test variable are given below. A large coefficient (highlighted in bold) indicates that the variable explains this factor. Factor 1 is determined by the two tests of spatial discrimination (S2-PD and MZ-PD); factor 2 is explained by the variable ADL SUBJECTS
Variables
Factor I
Factor 2
Static 2PD Moving 2PD Localization Pick-up test Gnosis Objects ADL
0.95237 0.93234 0.25315 0.88516 0.83434 0.57337 0.20366
0.20349 0.26394 0.88119 0.37462 0.39220 0.76473 0.82342
PARTIAL T COMPLETE
‘-1
VARIABLES ~ S2PD + M2PD
X GNOSIS * OBJECTS a ADL
-0.8 -0.6 -0.4 -0.2
0
FACTOR
Fig 1
0.2
0.4
0.6
0.8
0
0.2
0.4
0.6
0.8
1
1
Using the same factors with the x-axis representing factor 1 and the y-axis factor 2, the 14 cases are plotted. The clustering into two groups represents the subject sample divided into partial and complete nerve injuries. Factor 1 interpreted as the construct of sensory acuity differentiates between the two groups. Factor 2, interpreted as the ability to use sensory acuity and compensate for it, does not distinguish between the two groups as they both lie within the same co-ordinates of the y-axis.
LOCAL
. PICK-UP
‘1
-0.2
FACTOR
Fig 2
I
-0.8-0.6-0.4
1
1
Factor 1 is represented by the horizontal axis and factor 2 by the vertical axis. The variables that load highest on factor 1 are static 2-PD and moving 2-PD and thus determine the meaning of this factor. Factor 2 is determined by the variable ADL which lies closest to its axis.
are a measure of reinnervation density, this factor is of sensory acuity. interpreted as the construct by._ Consequently factor 2 which is largely determined _. the ADL test is interpreted as the construct 01 how well the patient is able to use that sensory acuity and also compensate for any lack of it through vision and sensorily intact digits. Using the factor loadings the coordinates for each subject are calculated and represented as a point on the same axis frame given in Figure 2. A clustering of subjects into two groups is evident which is in fact a differentiation of the subject sample between the complete and the partial nerve-injured patients. It is factor 1, interpreted as the construct of sensory acuity, which differentiates between partial and complete nerve lesions. However factor 2 does not distinguish between the two groups as they both lie within the same coordinates of the y-axis. This suggests that patient’s sensory acuity as assessed by the battery of tests is affected by the severity of their lesion but their ability to use their hands in activities of daily living remains unaffected.
DISCUSSION One of the objectives of the study was to develop a battery of tests which provides a valid, reliable and comprehensive assessment of outcome. Bell (1984) stated that sensory testing seeks to answer two questions: what is the sensory acuity of the hand and how well is the patient able to make use of it? The findings of this study would suggest that the battery of tests employed answered both these questions. Furthermore, through the inclusion of the timed ADL test the patient’s ability to use compensatory strategies was also assessed. It may be questioned whether both versions of the 2PD test need to be included as they are closely correlated. While the scores on the moving 2-PD test rendered slightly better scores than the static test this cannot be taken as evidence that moving 2-PD is a measure of the quickly-adapting receptors, which are believed to recover sooner and in larger numbers. Instead it has been suggested that moving the callipers of the diskriminator over the skin’s surface recruits a much larger number of receptors and thus provides improved threshold readings (Marsh, 1990). As the static 2-PD test correlates significantly with both tests of integrated hand function even when controlling for the patient’s age, delay before surgery and follow-up time, it should be used rather than the moving 2-PD test. The other objective of this study was to determine whether sensibility tests reflect the capacity of the hand to perform bilateral daily activities. The correlation between the six sensibility variables and the ADL test was significant in only three of the six variables. It is surprising that ADL did not correlate significantly with the timed pick-up test and object recognition test, particularly in view of the fact that they all use time as the critical measure. The preclusion of use of the ulnar
628
digits, the much smaller objects and the unfamiliarity of the pick-up and object recognition task may explain this. The factor analysis of the subjects further supports the findings that the sensibility tests do not predict the patient’s capacity to complete familiar everyday tasks. All patients had undergone a period of intensive rehabilitation in the 6 weeks following surgery in which early integrated use of the hand was encouraged. This may explain why patients’ ability to perform activities of daily living remained unaffected by the severity of the sensory deficit. The conclusions which may be drawn from this study are limited due to the relatively small sample on which the findings are based. A larger number of subjects could not be recruited as time was limited and the inclusion of subjects from other centres would have introduced confounding variables. The indications from this study are that tests of sensibility alone do not give an accurate and comprehensive assessment of the patient’s functional capacity after peripheral nerve repair. Therefore a measure of performance in everyday activities such as the one employed in this study should be included in an evaluation of outcome. Further research based on larger samples is required to confirm the findings of this study and also to establish the validity of sensory tests in terms of their correlation with neurophysiological parameters and integrated hand function. Acknowledgements This work was supported by a Department of Health Research Training Fellowship. The study was carried out while the author was a student on the MSc in Rehabilitation Studies course at the University of Southampton.
THE JOURNAL OF HAND SURGERY VOL. 18B No. 5 OCTOBER 1993
References BELL, J. A. Sensibility Tests: State of the Art. In: Hunter, .I. M., Schneider, L. H., Mackin, E. J. et al (Eds.): Rehabilitation of the Hand, 2nd Edn. St. Louis, C.V. Mosby, 1984 DELLON, A. L. and KALLMAN, C. H. (1983). Evaluation of functional sensation in the hand. Journal of Hand Surgery, 8: 6: 865-870. DELLON, A. L. Evaluation of Sensibility and Re-education of Sensation in the Hand. Baltimore, Williams & Wilkins, 198 1. DELLON, A. L. (1978). The moving two-point discrimination test: Clinical evaluation of the quickly adapting fibre receptor system. Journal of Hand Surgery, 3: 5: 474-481. LOUIS, D. S., GREENE, T. L., JACOBSON, K. E., RAMUSSEN, C., KOLOWICH, P. and GOLDSTEIN, S. A. (1984). Evaluation of normal values for stationary and moving two-point discrimination in the hand. Journal of Hand Surgery, 9A: 4: 552-555. MACKEL, R. (1985). Human cutaneous mechanoreceptors during regeneration: Physiology and interpretation. Annals in Neurology, 18: 165-172. MARSH, D. (1990). The validation of measures of outcome following suture of divided peripheral nerves supplying the hand. Journal of Hand Surgery, 15B: 1: 25-34. MARSH, D. The Measurement of Peripheral Nerve Function in the Upper Limb (unoublished M.D. Thesis) Cambridge Universitv. 1990. McQ-UILLAN, W. M., NEILSON, J. M.-M., BOARGMAN, A. K. and HAY, R. L. (1971). Sensory evaluation after median nerve repair. The Hand, 3: 1: 101-111. MOBERG, E. (1962). Criticisms and study of methods for examining sensibility in the hand. Neuroloev. 12: 8-19. MOBERG, E. (1958). Objective methods for determining the functional value of sensibility in the hand. Journal of Bone and Joint Surgery, 40B: 3: 454-476. SMITH, H. (1973). Smith Hand Function evaluation. American Journal of Occmxtional Therauv. 27: 5: 244-251. WYNN PARRY, C. B.-and SALTER, M. (1976). Sensory re-education after median nerve lesions. The Hand, 8: 3: 250-257. WYNN PARRY, C. B. Rehabilitation of the Hand, 2nd Edn. London, Butterworth. 1966.
Accepted: 24 March 1993 Christina Jerosch-Herold, MSc, OTR, Development, University of East An&,
DipCOT, Norwich
0
of the Hand
1993 The British
Society
for Surgery
Lecturer in Occupational NR4 7TJ, UK.
Therapy,
OPT
OUTCOME
IN MEDIAN
NERVE
INJURIES
C. JEROSCH-HEROLD
From the Rehabilitation Research Unit, University of Southampton, UK
Assessing the functional outcome of peripheral nerve suture in the hand requires a battery of tests which are valid, reliable and comprehensively evaluate cutaneous sensibility. This study explores the relationship between a battery of sensory tests and the patient’s capacity to perform everyday functional activities. An analysis of the interrelationship between all outcome variables reveals that the tests of sensibility do not predict the patients’ ability to use their hands in everyday activities, thus indicating that patients are able to compensate for sensory deficit through the use of vision and bilateral use of the hands. An assessment of outcome should therefore include an additional measure of performance on daily living tasks. Journal of Hand Surgery (British and European Volume, 1993) 18B: 624-628 METHODS
The assessment of recovery of functional sensibility after peripheral nerve repair to the hand remains a challenge to therapists and surgeons. Therapists are currently faced with a plethora of tests to choose from. Each test is often time-consuming and complex to administer and fatiguing for the patient. While the use of one single test may be attractive, particularly in a busy out-patient setting, such efforts have had to be abandoned in the light of the complexities of sensory neurophysiology. A battery of tests which correlate with neurophysiological parameters and integrated hand function is required to give a valid, reproducible and comprehensive assessment of sensory recovery. Such an assessment tool is an essential prerequisite for evaluating patients for further surgery, documenting progress and planning treatment, and rating compensation cases. While the literature on the validation of outcome measures for peripheral nerve repair is abundant there also still exists a controversy over the correlation between clinical sensory tests and the functional capacity of the injured hand. For example, in seeking to quantify the function of the hand in an objective manner, tests are often standardized to preclude the demonstration of compensatory strategies. Dellon (1981) suggests the taping of the little and ring fingers into the palm when testing integrated hand function for the median nerve, to stop the patient ‘cheating’. Yet if outcome measures seek to determine how well the patient is able to make use of his hands for everyday living then the strategies used to overcome residual deficit also need to be given consideration in an evaluation of outcome. Moreover, functional activities often involve bilateral use of the hands; thus while one hand may move in a much slower and less coordinated manner, both hands may function efficiently (Smith, 1973). A study was designed which sought to determine how best to assess sensory recovery in patients after peripheral nerve repair to the hand. The objectives of the study were two-fold: to compile a battery of tests which together provide a valid, reliable and comprehensive assessment of sensibility, and to establish whether the results from such tests correlate with the patient’s ability to perform activities of daily living.
A correlational design was used to investigate the strength of relationships between tests of sensibility and functional capacity of the hand 2 or more years after surgical repair of the median nerve at the wrist. Subjects acted as their own controls by comparing the results of the sensibility tests in the affected hand with the unaffected hand. Subjects 14 patients who had sustained a partial or complete median nerve lesion at the level of the wrist and who had undergone primary surgical repair at the same centre 2 or more years ago were included in the study. Fibre-end-organ relationships are considered to be sufficiently matured after 2 years for assessment of injuries at the wrist level (Mackel, 1985). Patients who had subsequently developed reflex sympathetic dystrophy or any other impairment affecting sensory-motor function of either upper limb were excluded. The age range was 19 to 61 years with a mean age of 38.1 years. Three patients were female and 11 were male. The average time since repair was 48.1 months (standard deviation 25.5 months). All patients had attended an intensive period of rehabilitation following surgery with the aim of returning to work at 6 to 12 weeks after injury depending on associated injury to the flexor tendons. None of the patients received any formal sensory re-education. Instrumentation A battery of sensory tests was compiled to provide a comprehensive assessment of the patient’s sensory recovery. The standardized method of application and rationale for their choice with reference to the literature is described here. The static two-point discrimination test (S2-PD). This was performed on the patient’s distal phalanges of the thumb, middle and ring fingers using the DellonMackinnon Diskriminator. The final threshold value for 624
MEDIAN
NERVE
625
INJURIES
each digit was determined as the smallest distance at which the patient was able to correctly discriminate seven out of ten random applications of one and two points. This test of spatial discrimination (Moberg, 1958) has been found to correlate with tests of integrated hand function (Moberg, 1962), thus indicating that it is a valid measure of functional sensibility. Subsequent studies however showed that patients with seemingly poor two-point discrimination demonstrate good integrated hand function (Wynn-Parry and Salter, 1976; McQuillan et al, 1970). One suggestion for this paradoxical observation is that the static 2-PD test measures the innervation density of the slowly-adapting receptor population. Active exploratory touch however is mediated by the quickly-adapting receptor population. The moving two-point discrimination test (M2-PD). This has been found to correlate with tests of integrated hand function (Dellon and Kallman, 1983). Dellon (1978) introduced this version of the test which involves moving the callipers over the skin’s surface. As the static and moving 2-PD tests are thought to test different neurophysiological parameters both were included in the assessment battery. Area localization (LOCAL).
This was tested using a modified version of the test used in a study by Marsh (1990) in which the territory of the injured nerve was divided into proximal, middle and distal zones and patients were asked to correctly localize a light moving touch with a cotton wool tip. Marsh (1990) found that most patients obtained very high scores, indicating that the test was possibly too easy. In this study only the distal phalanges were tested and the test rendered more difficult by dividing each phalanx into four zones giving a total of 12 zones for the median nerve distribution in each hand. Each correctly localized stimulus is given a score of 1 and any error 0.
The mod@ed pick-up test (PICKUP). This was used to obtain a measure of integrated hand function. In search of an answer to the question ‘What can the hand actually do?’ Moberg (1958) developed the pick-up test in which the patient is required to pick up small objects and place them in a container with and without vision. In order to standardize the test Dellon (1981) suggests taping the ulnar digits into the palm to avoid inadvertent use of sensorily intact areas. The objects used for this test have been varied and the norms published based on small samples (Wynn-Parry, 1966; Dellon, 1981). The version used by the author included ten small items (key, nut, bolt, nail, 50-pence piece, ten-pence piece, paperclip, safety pin, wing nut and washer). The patient is asked to pick up the ten items one at a time and place them in the container. This is then repeated and timed without vision. The average time of three trials is calculated for each hand.
Object recognition. This was also tested using the same ten items which are placed one at a time into the patient’s hand and the time taken to identify the object (GNOSIS) and the number correctly identified (OBJECTS) are recorded. The patient’s affected and unaffected hands were tested using all five assessments and the final score derived as
affected x10 unaffected A maximum score of 10 indicates normal sensibility. Using the unaffected hand as a control was considered more appropriate as many tests lack normative data and it has been established that hand dominance does not affect the scores in the two-point discrimination test (Louis et al, 1984) and the integrated hand function tests (Marsh 1990). A pilot study on 20 normal subjects was conducted to establish whether hand dominance has an effect on area localisation using a Wilcoxon signed rank test and no significant difference (P < 0.001) was found between left and right hand scores.
Activities of daily living (ADL)
Functional hand evaluations reported in the literature measure function unilaterally. However, patients sustaining injuries to the non-dominant hand would still be able to perform a unilateral task such as writing. Therefore four everyday tasks were selected which are normally performed bilaterally and irrespective of gender. They were: fastening a row of buttons on a reversible tabard, putting toothpaste on a toothbrush, taking a coin out of a purse and opening a jar of coffee. The same standardized items were used and patients were asked to perform each activity as they would normally do. The order of tasks was kept the same for every subject. Video-recordings were taken of each task being carried out for timing and for later analysis of the hand prehension patterns and strategies adopted. Patients were not informed that they were timed.
Statistical methods Univariate analysis of the results was carried out using the MINITAB (version 7.2) statistical package. The data followed a normal distribution with close means and medians, thus the use of parametric tests was considered appropriate. To facilitate the interpretation of how the variables interrelate principal component analysis was performed using the Statistical Package for the Social Sciences (SPSS PC+). This advanced statistical technique identifies a small number of factors or constructs which can be used to represent relationships among many variables.
626
THE JOURNAL OF HAND SURGERY VOL. 18B No. 5 OCTOBER 1993
RESULTS
(r= -0.4710, P=O.O42). In order to establish how all six test variables interrelate a multivariate analysis using principal component analysis with orthogonal rotation was carried out. This statistical technique is suitable for multivariate data and identifies a number of factors which can be used to interpret the relationship between several variables. In this study it was applied to see which tests grouped together to form a factor. The interpretation of what the factors represent is dependent upon which variables load highest on the factor. Two factors were extracted by computational analysis as they account for 87.6% of the variance in all the variables. The factor matrix in Table 3 gives the factor loadings for each of the seven variables. Using factors 1 and 2 to represent the x and y-axis respectively each variable is plotted using their factor loadings as coordinates (Fig 1). Given that factor 1 is determined mostly by the tests of static and moving two-point discrimination, which
The scores for the subject sample in all six sensibility variables and the ADL test are given in Table 1. The Pearson’s correlation coefficients and significance levels between the time taken to complete four tasks of ADL and the five sensibility test scores were calculated. In order to control for the possible effect of age at time of repair, delay between injury and suture, and time since repair, a partial correlation coefficient was computed for all the test variables and is given in Table 2. The negative sign of the correlation coefficient represents a positive relationship as good return of sensibility indicated by a high test score correlates with speed in ADL, that is fewer seconds to complete activities. A significant correlation was detected between ADL and moving 2-PD (r = - 0.5530, P= 0.041) ADL and localization (r = - 0.5700, P= 0.045) and ADL and the number of correctly identified objects in the gnosis test
Table l-The raw results from the subject sample. The scores on the six sensibility variables are calculated as a ratio of the unaffected hand, thus a score of 10 represents a normal score for that test and 0 that the patient is unable to perform the test Case
01 P 02 c 03 c 04 c 05 P 06 C 07 P 08 C 09 P 1oc 11c 12P 13P 14c
Sex
Age
M M F M M M M M M F M M F M
49 59 61 25 60 30 33 19 24 29 41 20 40 44
Delay follow-up Days
Months
0 0 0 1 2 10 0 1 0 0 I 1 0 1
24 56 65 21 26 48 24 25 59 90 32 26 83 89
S2PD
A42PD
Local
Pick-up
Gnosis
Objects
ADL in seconds
10 0 4 7 10 5 10 8 10 8 3 10 10 8
83.15 95.68 65.60 63.82 56.43 51.76 42.48 54.21 51.04 39.87 82.40 51.20 43.80 64.42
Scores as ratio of unaffected hand 3.3 0 0 0 9.3 0 5.6 1.5 9.2 1.0 0 6.7 5.9 0
3.3 0 0 1.1 10 0 6.8 1.9 10 2.5 0 7.9 7.2 0
10 0 1.5 10 10 8.3 10 1.5 9.2 7.5 2.5 8.3 8.0 10
8.24 0 1.1 4 8.8 2.2 8.8 5.5 10 3.5 3.8 8.0 6.4 3.65
1.23 0 2.8 2.6 10 1.0 10 3.3 10 2.2 1.8 8.9 7.3 3.4
C-complete injury. P-partial injury.
Table 2-The partial correlation coefficient and level of significance is given for all seven test variables. Coefficients highlighted in bold represent a significant relationship between two variables even after controlling for possible confounding effects of age, time since injury and delay till repair
M2PD Local Pick-up Gnosis Object ADL
SZPD
MZPD
Local
Pick-up
Gnosis
Object
0.9000 P < 0.001 0.3170 NS 0.8100 P < 0.001 0.7140 P = 0.004 0.5850 P = 0.032 - 0.5240 NS
0.3100 NS 0.7800 P < 0.001 0.6820 P=O.O06 0.5700 P = 0.033 - 0.5530 P = 0.041
0.5160 NS 0.4250 NS 0.7610 P = 0.002 - 0.5700 P = 0.045
0.6830 P < 0.001 0.6970 Pi 0.001 - 0.4330 NS
0.6000 P = 0.007 -0.3690 NS
- 0.4710 P = 0.042
NB n = 14 for all correlation coefficients.
MEDIAN
NERVE
INJURIES
Table 3-The two factors and their loadings for each test variable are given below. A large coefficient (highlighted in bold) indicates that the variable explains this factor. Factor 1 is determined by the two tests of spatial discrimination (S2-PD and MZ-PD); factor 2 is explained by the variable ADL SUBJECTS
Variables
Factor I
Factor 2
Static 2PD Moving 2PD Localization Pick-up test Gnosis Objects ADL
0.95237 0.93234 0.25315 0.88516 0.83434 0.57337 0.20366
0.20349 0.26394 0.88119 0.37462 0.39220 0.76473 0.82342
PARTIAL T COMPLETE
‘-1
VARIABLES ~ S2PD + M2PD
X GNOSIS * OBJECTS a ADL
-0.8 -0.6 -0.4 -0.2
0
FACTOR
Fig 1
0.2
0.4
0.6
0.8
0
0.2
0.4
0.6
0.8
1
1
Using the same factors with the x-axis representing factor 1 and the y-axis factor 2, the 14 cases are plotted. The clustering into two groups represents the subject sample divided into partial and complete nerve injuries. Factor 1 interpreted as the construct of sensory acuity differentiates between the two groups. Factor 2, interpreted as the ability to use sensory acuity and compensate for it, does not distinguish between the two groups as they both lie within the same co-ordinates of the y-axis.
LOCAL
. PICK-UP
‘1
-0.2
FACTOR
Fig 2
I
-0.8-0.6-0.4
1
1
Factor 1 is represented by the horizontal axis and factor 2 by the vertical axis. The variables that load highest on factor 1 are static 2-PD and moving 2-PD and thus determine the meaning of this factor. Factor 2 is determined by the variable ADL which lies closest to its axis.
are a measure of reinnervation density, this factor is of sensory acuity. interpreted as the construct by._ Consequently factor 2 which is largely determined _. the ADL test is interpreted as the construct 01 how well the patient is able to use that sensory acuity and also compensate for any lack of it through vision and sensorily intact digits. Using the factor loadings the coordinates for each subject are calculated and represented as a point on the same axis frame given in Figure 2. A clustering of subjects into two groups is evident which is in fact a differentiation of the subject sample between the complete and the partial nerve-injured patients. It is factor 1, interpreted as the construct of sensory acuity, which differentiates between partial and complete nerve lesions. However factor 2 does not distinguish between the two groups as they both lie within the same coordinates of the y-axis. This suggests that patient’s sensory acuity as assessed by the battery of tests is affected by the severity of their lesion but their ability to use their hands in activities of daily living remains unaffected.
DISCUSSION One of the objectives of the study was to develop a battery of tests which provides a valid, reliable and comprehensive assessment of outcome. Bell (1984) stated that sensory testing seeks to answer two questions: what is the sensory acuity of the hand and how well is the patient able to make use of it? The findings of this study would suggest that the battery of tests employed answered both these questions. Furthermore, through the inclusion of the timed ADL test the patient’s ability to use compensatory strategies was also assessed. It may be questioned whether both versions of the 2PD test need to be included as they are closely correlated. While the scores on the moving 2-PD test rendered slightly better scores than the static test this cannot be taken as evidence that moving 2-PD is a measure of the quickly-adapting receptors, which are believed to recover sooner and in larger numbers. Instead it has been suggested that moving the callipers of the diskriminator over the skin’s surface recruits a much larger number of receptors and thus provides improved threshold readings (Marsh, 1990). As the static 2-PD test correlates significantly with both tests of integrated hand function even when controlling for the patient’s age, delay before surgery and follow-up time, it should be used rather than the moving 2-PD test. The other objective of this study was to determine whether sensibility tests reflect the capacity of the hand to perform bilateral daily activities. The correlation between the six sensibility variables and the ADL test was significant in only three of the six variables. It is surprising that ADL did not correlate significantly with the timed pick-up test and object recognition test, particularly in view of the fact that they all use time as the critical measure. The preclusion of use of the ulnar
628
digits, the much smaller objects and the unfamiliarity of the pick-up and object recognition task may explain this. The factor analysis of the subjects further supports the findings that the sensibility tests do not predict the patient’s capacity to complete familiar everyday tasks. All patients had undergone a period of intensive rehabilitation in the 6 weeks following surgery in which early integrated use of the hand was encouraged. This may explain why patients’ ability to perform activities of daily living remained unaffected by the severity of the sensory deficit. The conclusions which may be drawn from this study are limited due to the relatively small sample on which the findings are based. A larger number of subjects could not be recruited as time was limited and the inclusion of subjects from other centres would have introduced confounding variables. The indications from this study are that tests of sensibility alone do not give an accurate and comprehensive assessment of the patient’s functional capacity after peripheral nerve repair. Therefore a measure of performance in everyday activities such as the one employed in this study should be included in an evaluation of outcome. Further research based on larger samples is required to confirm the findings of this study and also to establish the validity of sensory tests in terms of their correlation with neurophysiological parameters and integrated hand function. Acknowledgements This work was supported by a Department of Health Research Training Fellowship. The study was carried out while the author was a student on the MSc in Rehabilitation Studies course at the University of Southampton.
THE JOURNAL OF HAND SURGERY VOL. 18B No. 5 OCTOBER 1993
References BELL, J. A. Sensibility Tests: State of the Art. In: Hunter, .I. M., Schneider, L. H., Mackin, E. J. et al (Eds.): Rehabilitation of the Hand, 2nd Edn. St. Louis, C.V. Mosby, 1984 DELLON, A. L. and KALLMAN, C. H. (1983). Evaluation of functional sensation in the hand. Journal of Hand Surgery, 8: 6: 865-870. DELLON, A. L. Evaluation of Sensibility and Re-education of Sensation in the Hand. Baltimore, Williams & Wilkins, 198 1. DELLON, A. L. (1978). The moving two-point discrimination test: Clinical evaluation of the quickly adapting fibre receptor system. Journal of Hand Surgery, 3: 5: 474-481. LOUIS, D. S., GREENE, T. L., JACOBSON, K. E., RAMUSSEN, C., KOLOWICH, P. and GOLDSTEIN, S. A. (1984). Evaluation of normal values for stationary and moving two-point discrimination in the hand. Journal of Hand Surgery, 9A: 4: 552-555. MACKEL, R. (1985). Human cutaneous mechanoreceptors during regeneration: Physiology and interpretation. Annals in Neurology, 18: 165-172. MARSH, D. (1990). The validation of measures of outcome following suture of divided peripheral nerves supplying the hand. Journal of Hand Surgery, 15B: 1: 25-34. MARSH, D. The Measurement of Peripheral Nerve Function in the Upper Limb (unoublished M.D. Thesis) Cambridge Universitv. 1990. McQ-UILLAN, W. M., NEILSON, J. M.-M., BOARGMAN, A. K. and HAY, R. L. (1971). Sensory evaluation after median nerve repair. The Hand, 3: 1: 101-111. MOBERG, E. (1962). Criticisms and study of methods for examining sensibility in the hand. Neuroloev. 12: 8-19. MOBERG, E. (1958). Objective methods for determining the functional value of sensibility in the hand. Journal of Bone and Joint Surgery, 40B: 3: 454-476. SMITH, H. (1973). Smith Hand Function evaluation. American Journal of Occmxtional Therauv. 27: 5: 244-251. WYNN PARRY, C. B.-and SALTER, M. (1976). Sensory re-education after median nerve lesions. The Hand, 8: 3: 250-257. WYNN PARRY, C. B. Rehabilitation of the Hand, 2nd Edn. London, Butterworth. 1966.
Accepted: 24 March 1993 Christina Jerosch-Herold, MSc, OTR, Development, University of East An&,
DipCOT, Norwich
0
of the Hand
1993 The British
Society
for Surgery
Lecturer in Occupational NR4 7TJ, UK.
Therapy,
OPT