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THE LONG TERM RECOVERY CURVE IN ADULTS AFTER MEDIAN OR ULNAR NERVE REPAIR: A REFERENCE INTERVAL
THE LONG TERM RECOVERY CURVE IN ADULTS AFTER MEDIAN OR ULNAR NERVE REPAIR: A REFERENCE INTERVAL B. ROSE´N and G. LUNDBORG From the Department of Hand Surgery, Malmo¨ University Hospital, Lund University, Sweden
This study presents a predicted five-year reference interval for the outcome following repair of the median or ulnar nerve in adults. Forty-four patients were examined with the use of a recently introduced model instrument for documentation after nerve repair that includes ‘‘sensory’’, ‘‘motor’’, and ‘‘pain/discomfort’’ outcomes which together constitute a summarized ‘‘total score’’. Analysis of the ‘‘total score’’ showed that follow-up time and age significantly influence the outcome. There were obvious inferior ‘‘motor’’ results after ulnar nerve injury, but these did not significantly influence the ‘‘total score’’. Significant improvements in the ‘‘total score’’ were seen throughout the follow-up period. Journal of Hand Surgery (British and European Volume, 2001) 26B: 3: 196–200
transection of the median (n ¼ 21) or ulnar (n ¼ 23) nerve at wrist or in the distal forearm, at the Department of Hand Surgery, Malmo¨ University Hospital between 1994 and 1999. They were 40 men and four women with a mean age of 35 (range, 18–72). Thirty one patients were operated on with a conventional suture technique, and 13 with silicone tube technique (Lundborg et al., 1997) All patients were informed about the principles of sensory re-education (Dellon et al., 1974; Wynn-Parry and Salter, 1976), and all were encouraged to integrate the sensory re-education exercises in their daily activities.
INTRODUCTION Transection and repair of a peripheral nerve has considerable functional consequences for the individual, due to sensory and motor loss, as well as the pain and discomfort from hyperaesthesia and cold intolerance. The outcome is influenced by both peripheral and central factors, and these need to be examined and documented in order to plan optimal interventions during rehabilitation, and to allow a valid and reliable evaluation of the outcome (Dellon, 1981; Ewing-Fess, 1986; Lundborg, 1988; McAllister and Calder, 1995). We have recently introduced a new model for quantitative documentation of the functional outcome after nerve injury and repair which uses a numerical scoring protocol (Rose´n and Lundborg, 2000). The model includes results from selected assessments, which reflect sensory, motor, and pain/discomfort domains, and produces a ‘‘total score’’ which summarizes the findings (Fig 1). The ‘‘total score’’ has a strong correlation with the patients’ opinions concerning the influence of the nerve injury on their activities of daily living. Results of validity and reliability investigations and details regarding the new model for documentation are described in a previous report (Rose´n and Lundborg, 2000). The aim of this study was to assess the changes which occurred with time in the functional outcome following median or ulnar nerve repair in adults, and to establish reference material for clinical use during the rehabilitation. The effect of age within a group of adults, as well as potential differences in outcome between patients with median and ulnar nerve repair, were also investigated.
Assessment The examinations were performed at 3, 6, 12, 24, 36–48 and 60 months postoperatively, and each patient was examined on between one and six occasions. In all, 129 assessments were performed. The assessments were done according to a standardized test procedure and were performed by experienced occupational therapists. Numerical scoring with a summarized ‘‘total score’’ was done in accordance with a new model instrument for documentation of the outcome after nerve repair. This included assessments of the sensory, motor and pain/discomfort outcomes (Fig 1). The detailed procedure of the assessments and the scoring system are described in a previous report (Rose´n and Lundborg, 2000).
Sensory outcome
MATERIAL AND METHODS
.
Patients The study included 44 consecutive adults who underwent rehabilitation after surgery for complete
.
196
The pocket version of Semmes–Weinstein monofilaments was used in the manner described by Bell-Krotoski (1995). Tactile gnosis was assessed using both static twopoint discrimination (s2PD) according to Moberg
OUTCOME OF NERVE REPAIR
197
198
.
THE JOURNAL OF HAND SURGERY VOL. 26B No. 3 JUNE 2001
(ASHT, 1992; Moberg, 1990), and the STI-testTM (Shape/Texture Identification test) (Rose´n and Lundborg, 1998). Finger dexterity was assessed with three parts of the Sollerman hand function test (pick up coins from purses, put nuts on bolts, and do up buttons (Sollerman and Ejeska¨r, 1995).
Motor outcome .
.
Muscle strength was assessed with Manual Muscle Strength Testing according to the MRC system (Brandsma et al., 1995; MRC, 1954). For median nerve injuries the power of thumb palmar abduction was assessed, and for ulnar nerve injuries index and little finger abduction, and little finger adduction were examined. Grip strength was measured using a Jamar dynamometer as described by Mathiowetz et al. (1984).
Pain/discomfort outcome The patients were asked to grade problems due to hyperaesthesia and cold intolerance on a 0–3 scale (Fig 1) (Rose´n, 1996). Analysis An analysis of covariance (ANCOVA) was performed on the repeated measurements of the ‘‘total score’’ (sum of sensory, motor and pain/discomfort outcome scores). Two factors (age and nerve) were used, and follow-up time was covariat. Additional analyses of the separate domains with Spearman’s correlation were done to investigate the influence of age. Residual analysis with log of time fulfilled the assumption of normality for ANCOVA analysis. RESULTS Age at surgery and the length of follow-up significantly influenced the ‘‘total score’’ (P 5 0.001). Raw data from the ‘‘motor’’ outcome showed obviously worse results for the patients with ulnar nerve injuries at all follow up times (Fig 2). However, the ‘‘total scores’’ for the median and ulnar nerves were not significantly different.
Fig 2 Raw data for the results in the sensory, motor, and pain/ discomfort domains in patients with median or ulnar nerve repairs at the six follow-up occasions. (The boxes represent quartiles and the whiskers the nonoutliers range.)
A reference interval for the outcome after nerve repair, as measured by our model, is presented in Fig 3. Corrections were made for the influences of age at surgery and follow-up time. The comparison of the scores between each follow-up time showed significant changes in the ‘‘total score’’ at
3————————————————————————————————————————————————————————————— Fig 1 The suggested numerical test protocol, illustrated here by the follow-up results of a man with ulnar nerve repair at the wrist. Instructions for use of the protocol: To make a general view of the results easier, the results from each instrument are expressed as the quotient between the obtained and normal results. For example in ‘‘sensory innervation’’, the results from the monofilament test in the marked critical sites for the relevant nerve (median: tip of thumb and index fingers, and proximal phalanx of index finger; ulnar: tip and base of little finger and base of hypothenar, are quantified as 0–5 according to instructions in the ‘‘Instrument and quantification’’ column. The results are then added together to give a maximum of 15 points. The patient’s score is then calculated by dividing the obtained result with the normal (15) outcome. Scores for the following assessments are calculated in the same manner. Since the three domains (sensory, motor, pain/ discomfort) do not contain an identical number of assessment instruments, the mean score for each domain is calculated. The maximum score in each domain is therefore 1. The mean scores from the three domains are finally summarised as a ‘‘total score’’, and the maximum score is consequently 3.
OUTCOME OF NERVE REPAIR
199
Table 1—Medians and interquatile ranges of the oucome scores for the sensory, motor and pain/discomfort domains (0–1), and the summarized total score (0–3) Months postoperatively n Sensory Motor Pain/discomfort Total score
Fig 3 Estimated predicted values for ‘‘total score’’ after repair of the median or ulnar nerve in the distal forearm or at the wrist in adults. The shaded area represents the 95% individual prediction interval.
all the follow-up intevals (P = 0.001), Table 1. There was no significant interaction (P = 0.8) between the injured nerve and the follow-up time: in other words the recovery, as expressed by the ‘‘total score’’, did not differ significantly during the follow-up between the median and ulnar nerve injured patients. Additional analyses of the influence of age at each follow-up time showed that age correlated significantly (P 0.02) with the results from the sensory domain. Younger adults had significantly better results from the 6 months follow-up onwards, and the influence of age on the sensory outcome became stronger with time. The correlation coefficient was 0.45 at the 6 month followup, and 0.71 at the 60 month follow-up. Age did not influence the motor and pain/discomfort outcomes. DISCUSSION Age was an influencing factor within this adult group, and a closer analysis showed that this significantly influenced the sensory recovery. It is well known that the recovery after nerve repair in children is superior to that in adults (Birch and Raji, 1991; O¨nne, 1962), and this is often explained by the better capacity of children to adapt to the reorganization of the central nervous system that follows nerve repair (Almquist et al., 1983; Florence et al., 1996; Hudson et al., 1997; Lundborg, 2000). With sensory re-education adults can to some extent use the plasticity of the brain to learn to interpret the new pattern of the sensory cortex representation when touching different objects (Dellon, 1997; Imai et al., 1991; Jenkins et al., 1990; Wynn-Parry and Salter,
3 21
6 26
12 27
24 18
36/48 22
60 15
0.21 0.32 0.40 0.42 0.46 0.58 (0.15) (0.17) (0.12) (0.19) (0.16) (0.19) 0.38 0.41 0.60 0.75 0.81 0.85 (0.35) (0.45) (0.37) (0.34) (0.18) (0.23) 0.50 0.42 0.50 0.50 0.67 0.83 (0.31) (0.33) (0.33) (0.33) (0.50) (0.42) 1.2 1.3 1.6 1.7 1.9 2.2 (0.3) (0.5) (0.5) (0.5) (0.4) (0.5)
1976). Cognitive capacity factors may also play a role in the adaptation to the altered cortical representation (Rose´n et al., 1994). This study also illustrates the larger motor component of the ulnar nerve, and there was a considerable difference in the recovery of motor function after median and ulnar nerve repairs. However, the longitudinal design of the study with repeated measurements required corrections for length of follow-up and age and, after this had been considered, the ‘‘injured nerve’’ was not a significant predictor of the ‘‘total score’’. The pros and cons of the dilutive effect when summarizing several outcome results has been discussed in our previous report of this model (Rose´n and Lundborg, 2000). One could argue that the ‘‘total score’’ is of less clinical significance than the outcomes for each of the three separate domains (‘‘sensory’’, ‘‘motor’’, and ‘‘pain/ discomfort’’). But the ‘‘total score’’ has the strongest relationship with the ability to perform activities of daily living (Rose´n and Lundborg, 2000). Significant improvements occurred in the ‘‘total score’’ throughout the follow-up, for up to 5 years after the repair. This may be due to continuing regeneration and reinnervation and the long term maturation process for nerve fibres and mechanoreceptors. Alternatively it may reflect a physiological and psychological adaptation to the new situation. A valid criticism of this study is that not all patients were examined at each follow-up time, but this was corrected for in the statistical analyses. Our method of assessing recovery was only designed in 1994, and thus some of our early patients were not assessed early in their recovery. In addition practical issues, such as long distances to travel, also caused dropout of patients. Our results might change if a larger population was studied, and trends seen in this study might then become clearer. The model for documenting the recovery on which the present results are based provides an overview of the recovery with information on the overall disability level, as well as more detailed information on impairment level (WHO, 1980; WHO, 1999). Information from individual assessments is provided as numerical data and we have produced a 95% reference interval, which
200
enables a detailed focus on the temporal aspects of the process of regeneration and recovery. This allows prediction of the expected recovery in adults during their rehabilitation after nerve repair. Acknowledgements Grants from the Swedish Medical Research Council (no. 5188), Lund University, The Swedish Foundation for Health Care Sciences and Allergy Research supported this study. Special thanks to Jan A˚ke Nilsson, Department of Statistics and Information processing, University Hospital MAS for statistical expert advice, and to Ingela Carlsson, Rosmarie Jutemark, Marianne Neving, Magnus Sko¨ldba¨ck at the Rehabilitation Unit, Department of Hand Surgery, University Hospital MAS, for help in collecting data.
References Almquist EE, Smith OA, Fry L (1983). Nerve conduction velocity, microscopic, and electron microscopy studies comparing repaired adult and baby monkey median nerves. Journal of Hand Surgery, 8: 404–410. American Society of Hand Therapists (ASHT). Clinical Assessment Recommendations. 2nd edn. 1992. www.asht.org. Bell-Krotoski JA. Sensibility testing: Current Concepts. In: Hunter JM, Mackin EJ, Callahan AD (Eds). Rehabilitation of the Hand. St Louis CV Mosby Compnay, 1995: 109–128. Birch R, Raji A (1991). Repair of median and ulnar nerves – primary suture is best. Journal of Bone and Joint Surgery, 73B: 154–157. Brandsma JW, Schreuders TA, Birke JA, Piefer A, Oostendorp R (1995). Manual muscle testing. Intra- and interobserver reliability of the intrinsic muscles of the hand. Journal of Hand Therapy, 8: 185–190. Dellon AL. Somatosensory testing and rehabilitation. The American Occupational Therapy Association, Inc. Bethseda, 1997. Dellon AL. Sensibility and re-education of sensation in the hand. Baltimore, Williams & Wilkins, 1981. Dellon AL, Curtis R, Edgerton MT (1974). Reeducation of sensation in the hand after nerve injury and repair. Plastic & Reconstructive Surgery, 53: 297–305. Ewing-Fess E (1986). The need for reliability and validity in hand assessment instruments. Journal of Hand Surgery, 11A: 621–623. Florence SL, Jain N, Pospichal MW, Beck PD, Sly DL, Kaas JH (1996). Central reorganization of sensory pathways following peripheral nerve regeneration in fetal monkeys. Nature, 381: 69. Hudson DA, Bolitho DG, Hodgetts K (1997). Primary epineural repair of the median nerve in children. Journal of Hand Surgery, 22B: 54–56. Imai H, Tajima T, Natsumi Y (1991). Succesful re-education of functional sensibility after median nerve repair at the wrist. Journal of Hand Surgery, 16A: 60–65. Jenkins WM, Merzenich MM, Ochs MT, Allard T, Guic-Robles E (1990). Functional reorganization of primary somatosensory cortex in adult owl
THE JOURNAL OF HAND SURGERY VOL. 26B No. 3 JUNE 2001 monkeys after behaviorally controlled tactile stimulation. Journal of Neurophysiology, 63: 82–104. Lundborg G. Nerve injury and repair. Edinburgh, Churchill Livingstone, 1988. Lundborg G (2000). Brain plasticity and hand surgery – an overview. Journal of Hand Surgery, 25B: 242–252. Lundborg G, Rose´n B, Dahlin L, Danielsen N, Holmberg J (1997). Tubular versus conventional repair of median and ulnar nerves in the human forearm: Early results from a prospective, randomized, clinical study. Journal of Hand Surgery, 22A: 99–106. Mathiowetz V, Kashman N, Volland G, Weber K, Dowe M, Rogers S (1985). Grip and pinch strength. Normative data for adults. Archives of Physical Medicine and Rehabilitation, 66: 69–74. McAllister RMR, Calder JS (1995). Paradoxical clinical consequenses of peripheral nerve injury: a review of anatomical, neurophysiological and psychological mechanisms. British Journal of Plastic Surgery, 48: 384–395. Medical Research Council (MRC) Results of nerve suture. In: Seddon HJ (Ed.) Peripheral nerve injuries, London, Her Majesty’s Stationery Office, 1954. Moberg E (1990). Two-point discrimination test: a valuable part of hand surgical rehabilitation in tetreplegia. Scandinavian Journal of Rehabilitation Medicine, 22: 127–134. O¨nne L (1962). Recovery of sensibility and sudomotor activity in the hand after nerve suture. Acta Chirurgica Scandinavica, Suppl 300 1. Rose´n B (1996). Recovery of sensory and motor function. A rationale for evaluation. Journal of Hand Therapy, 9: 315–327. Rose´n B, Lundborg G (1998). A new tactile gnosis instrument in sensibility testing. Journal of Hand Therapy, 11: 251–257. Rose´n B, Lundborg G (2000). A model instrument for the documentation of outcome after nerve repair. Journal of Hand Surgery, 25A: 535–543. Rose´n B, Lundborg G, Dahlin LB, Holmberg J, Karlsson B (1994). Nerve repair: correlation of restitution of functional sensibility with specific cognitive capacities. Journal of Hand Surgery, 19B: 452–458. Sollerman C, Ejeska¨r, A (1995). Sollerman hand function test: a standardized method and its use in tetraplegic patients. Scandinavian Journal of Plastic and Reconstructive Surgery, 29: 167–173. WHO. International classification of impairments, disabilities, and handicaps: a manual of classification relating to the consequences of disease. Geneva, 1980. WHO. International classification of functioning and disability. A manual of classification relating to the consequences of disease (ICIDH-2). Geneva, 1999. Wynn-Parry CB, Salter M (1976). Sensory re-education after median nerve lesions. The Hand, 8: 250–257. Received: 17 February 2000 Accepted after revision: 24 January 2001 Ms Birgitta Rose´n, Department of Hand Surgery, Malmo¨ University Hospital, S-205 02 Malmo¨, Sweden. E-mail: [email protected] # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2001.0567, available online at http://www.idealibrary.com on
This study presents a predicted five-year reference interval for the outcome following repair of the median or ulnar nerve in adults. Forty-four patients were examined with the use of a recently introduced model instrument for documentation after nerve repair that includes ‘‘sensory’’, ‘‘motor’’, and ‘‘pain/discomfort’’ outcomes which together constitute a summarized ‘‘total score’’. Analysis of the ‘‘total score’’ showed that follow-up time and age significantly influence the outcome. There were obvious inferior ‘‘motor’’ results after ulnar nerve injury, but these did not significantly influence the ‘‘total score’’. Significant improvements in the ‘‘total score’’ were seen throughout the follow-up period. Journal of Hand Surgery (British and European Volume, 2001) 26B: 3: 196–200
transection of the median (n ¼ 21) or ulnar (n ¼ 23) nerve at wrist or in the distal forearm, at the Department of Hand Surgery, Malmo¨ University Hospital between 1994 and 1999. They were 40 men and four women with a mean age of 35 (range, 18–72). Thirty one patients were operated on with a conventional suture technique, and 13 with silicone tube technique (Lundborg et al., 1997) All patients were informed about the principles of sensory re-education (Dellon et al., 1974; Wynn-Parry and Salter, 1976), and all were encouraged to integrate the sensory re-education exercises in their daily activities.
INTRODUCTION Transection and repair of a peripheral nerve has considerable functional consequences for the individual, due to sensory and motor loss, as well as the pain and discomfort from hyperaesthesia and cold intolerance. The outcome is influenced by both peripheral and central factors, and these need to be examined and documented in order to plan optimal interventions during rehabilitation, and to allow a valid and reliable evaluation of the outcome (Dellon, 1981; Ewing-Fess, 1986; Lundborg, 1988; McAllister and Calder, 1995). We have recently introduced a new model for quantitative documentation of the functional outcome after nerve injury and repair which uses a numerical scoring protocol (Rose´n and Lundborg, 2000). The model includes results from selected assessments, which reflect sensory, motor, and pain/discomfort domains, and produces a ‘‘total score’’ which summarizes the findings (Fig 1). The ‘‘total score’’ has a strong correlation with the patients’ opinions concerning the influence of the nerve injury on their activities of daily living. Results of validity and reliability investigations and details regarding the new model for documentation are described in a previous report (Rose´n and Lundborg, 2000). The aim of this study was to assess the changes which occurred with time in the functional outcome following median or ulnar nerve repair in adults, and to establish reference material for clinical use during the rehabilitation. The effect of age within a group of adults, as well as potential differences in outcome between patients with median and ulnar nerve repair, were also investigated.
Assessment The examinations were performed at 3, 6, 12, 24, 36–48 and 60 months postoperatively, and each patient was examined on between one and six occasions. In all, 129 assessments were performed. The assessments were done according to a standardized test procedure and were performed by experienced occupational therapists. Numerical scoring with a summarized ‘‘total score’’ was done in accordance with a new model instrument for documentation of the outcome after nerve repair. This included assessments of the sensory, motor and pain/discomfort outcomes (Fig 1). The detailed procedure of the assessments and the scoring system are described in a previous report (Rose´n and Lundborg, 2000).
Sensory outcome
MATERIAL AND METHODS
.
Patients The study included 44 consecutive adults who underwent rehabilitation after surgery for complete
.
196
The pocket version of Semmes–Weinstein monofilaments was used in the manner described by Bell-Krotoski (1995). Tactile gnosis was assessed using both static twopoint discrimination (s2PD) according to Moberg
OUTCOME OF NERVE REPAIR
197
198
.
THE JOURNAL OF HAND SURGERY VOL. 26B No. 3 JUNE 2001
(ASHT, 1992; Moberg, 1990), and the STI-testTM (Shape/Texture Identification test) (Rose´n and Lundborg, 1998). Finger dexterity was assessed with three parts of the Sollerman hand function test (pick up coins from purses, put nuts on bolts, and do up buttons (Sollerman and Ejeska¨r, 1995).
Motor outcome .
.
Muscle strength was assessed with Manual Muscle Strength Testing according to the MRC system (Brandsma et al., 1995; MRC, 1954). For median nerve injuries the power of thumb palmar abduction was assessed, and for ulnar nerve injuries index and little finger abduction, and little finger adduction were examined. Grip strength was measured using a Jamar dynamometer as described by Mathiowetz et al. (1984).
Pain/discomfort outcome The patients were asked to grade problems due to hyperaesthesia and cold intolerance on a 0–3 scale (Fig 1) (Rose´n, 1996). Analysis An analysis of covariance (ANCOVA) was performed on the repeated measurements of the ‘‘total score’’ (sum of sensory, motor and pain/discomfort outcome scores). Two factors (age and nerve) were used, and follow-up time was covariat. Additional analyses of the separate domains with Spearman’s correlation were done to investigate the influence of age. Residual analysis with log of time fulfilled the assumption of normality for ANCOVA analysis. RESULTS Age at surgery and the length of follow-up significantly influenced the ‘‘total score’’ (P 5 0.001). Raw data from the ‘‘motor’’ outcome showed obviously worse results for the patients with ulnar nerve injuries at all follow up times (Fig 2). However, the ‘‘total scores’’ for the median and ulnar nerves were not significantly different.
Fig 2 Raw data for the results in the sensory, motor, and pain/ discomfort domains in patients with median or ulnar nerve repairs at the six follow-up occasions. (The boxes represent quartiles and the whiskers the nonoutliers range.)
A reference interval for the outcome after nerve repair, as measured by our model, is presented in Fig 3. Corrections were made for the influences of age at surgery and follow-up time. The comparison of the scores between each follow-up time showed significant changes in the ‘‘total score’’ at
3————————————————————————————————————————————————————————————— Fig 1 The suggested numerical test protocol, illustrated here by the follow-up results of a man with ulnar nerve repair at the wrist. Instructions for use of the protocol: To make a general view of the results easier, the results from each instrument are expressed as the quotient between the obtained and normal results. For example in ‘‘sensory innervation’’, the results from the monofilament test in the marked critical sites for the relevant nerve (median: tip of thumb and index fingers, and proximal phalanx of index finger; ulnar: tip and base of little finger and base of hypothenar, are quantified as 0–5 according to instructions in the ‘‘Instrument and quantification’’ column. The results are then added together to give a maximum of 15 points. The patient’s score is then calculated by dividing the obtained result with the normal (15) outcome. Scores for the following assessments are calculated in the same manner. Since the three domains (sensory, motor, pain/ discomfort) do not contain an identical number of assessment instruments, the mean score for each domain is calculated. The maximum score in each domain is therefore 1. The mean scores from the three domains are finally summarised as a ‘‘total score’’, and the maximum score is consequently 3.
OUTCOME OF NERVE REPAIR
199
Table 1—Medians and interquatile ranges of the oucome scores for the sensory, motor and pain/discomfort domains (0–1), and the summarized total score (0–3) Months postoperatively n Sensory Motor Pain/discomfort Total score
Fig 3 Estimated predicted values for ‘‘total score’’ after repair of the median or ulnar nerve in the distal forearm or at the wrist in adults. The shaded area represents the 95% individual prediction interval.
all the follow-up intevals (P = 0.001), Table 1. There was no significant interaction (P = 0.8) between the injured nerve and the follow-up time: in other words the recovery, as expressed by the ‘‘total score’’, did not differ significantly during the follow-up between the median and ulnar nerve injured patients. Additional analyses of the influence of age at each follow-up time showed that age correlated significantly (P 0.02) with the results from the sensory domain. Younger adults had significantly better results from the 6 months follow-up onwards, and the influence of age on the sensory outcome became stronger with time. The correlation coefficient was 0.45 at the 6 month followup, and 0.71 at the 60 month follow-up. Age did not influence the motor and pain/discomfort outcomes. DISCUSSION Age was an influencing factor within this adult group, and a closer analysis showed that this significantly influenced the sensory recovery. It is well known that the recovery after nerve repair in children is superior to that in adults (Birch and Raji, 1991; O¨nne, 1962), and this is often explained by the better capacity of children to adapt to the reorganization of the central nervous system that follows nerve repair (Almquist et al., 1983; Florence et al., 1996; Hudson et al., 1997; Lundborg, 2000). With sensory re-education adults can to some extent use the plasticity of the brain to learn to interpret the new pattern of the sensory cortex representation when touching different objects (Dellon, 1997; Imai et al., 1991; Jenkins et al., 1990; Wynn-Parry and Salter,
3 21
6 26
12 27
24 18
36/48 22
60 15
0.21 0.32 0.40 0.42 0.46 0.58 (0.15) (0.17) (0.12) (0.19) (0.16) (0.19) 0.38 0.41 0.60 0.75 0.81 0.85 (0.35) (0.45) (0.37) (0.34) (0.18) (0.23) 0.50 0.42 0.50 0.50 0.67 0.83 (0.31) (0.33) (0.33) (0.33) (0.50) (0.42) 1.2 1.3 1.6 1.7 1.9 2.2 (0.3) (0.5) (0.5) (0.5) (0.4) (0.5)
1976). Cognitive capacity factors may also play a role in the adaptation to the altered cortical representation (Rose´n et al., 1994). This study also illustrates the larger motor component of the ulnar nerve, and there was a considerable difference in the recovery of motor function after median and ulnar nerve repairs. However, the longitudinal design of the study with repeated measurements required corrections for length of follow-up and age and, after this had been considered, the ‘‘injured nerve’’ was not a significant predictor of the ‘‘total score’’. The pros and cons of the dilutive effect when summarizing several outcome results has been discussed in our previous report of this model (Rose´n and Lundborg, 2000). One could argue that the ‘‘total score’’ is of less clinical significance than the outcomes for each of the three separate domains (‘‘sensory’’, ‘‘motor’’, and ‘‘pain/ discomfort’’). But the ‘‘total score’’ has the strongest relationship with the ability to perform activities of daily living (Rose´n and Lundborg, 2000). Significant improvements occurred in the ‘‘total score’’ throughout the follow-up, for up to 5 years after the repair. This may be due to continuing regeneration and reinnervation and the long term maturation process for nerve fibres and mechanoreceptors. Alternatively it may reflect a physiological and psychological adaptation to the new situation. A valid criticism of this study is that not all patients were examined at each follow-up time, but this was corrected for in the statistical analyses. Our method of assessing recovery was only designed in 1994, and thus some of our early patients were not assessed early in their recovery. In addition practical issues, such as long distances to travel, also caused dropout of patients. Our results might change if a larger population was studied, and trends seen in this study might then become clearer. The model for documenting the recovery on which the present results are based provides an overview of the recovery with information on the overall disability level, as well as more detailed information on impairment level (WHO, 1980; WHO, 1999). Information from individual assessments is provided as numerical data and we have produced a 95% reference interval, which
200
enables a detailed focus on the temporal aspects of the process of regeneration and recovery. This allows prediction of the expected recovery in adults during their rehabilitation after nerve repair. Acknowledgements Grants from the Swedish Medical Research Council (no. 5188), Lund University, The Swedish Foundation for Health Care Sciences and Allergy Research supported this study. Special thanks to Jan A˚ke Nilsson, Department of Statistics and Information processing, University Hospital MAS for statistical expert advice, and to Ingela Carlsson, Rosmarie Jutemark, Marianne Neving, Magnus Sko¨ldba¨ck at the Rehabilitation Unit, Department of Hand Surgery, University Hospital MAS, for help in collecting data.
References Almquist EE, Smith OA, Fry L (1983). Nerve conduction velocity, microscopic, and electron microscopy studies comparing repaired adult and baby monkey median nerves. Journal of Hand Surgery, 8: 404–410. American Society of Hand Therapists (ASHT). Clinical Assessment Recommendations. 2nd edn. 1992. www.asht.org. Bell-Krotoski JA. Sensibility testing: Current Concepts. In: Hunter JM, Mackin EJ, Callahan AD (Eds). Rehabilitation of the Hand. St Louis CV Mosby Compnay, 1995: 109–128. Birch R, Raji A (1991). Repair of median and ulnar nerves – primary suture is best. Journal of Bone and Joint Surgery, 73B: 154–157. Brandsma JW, Schreuders TA, Birke JA, Piefer A, Oostendorp R (1995). Manual muscle testing. Intra- and interobserver reliability of the intrinsic muscles of the hand. Journal of Hand Therapy, 8: 185–190. Dellon AL. Somatosensory testing and rehabilitation. The American Occupational Therapy Association, Inc. Bethseda, 1997. Dellon AL. Sensibility and re-education of sensation in the hand. Baltimore, Williams & Wilkins, 1981. Dellon AL, Curtis R, Edgerton MT (1974). Reeducation of sensation in the hand after nerve injury and repair. Plastic & Reconstructive Surgery, 53: 297–305. Ewing-Fess E (1986). The need for reliability and validity in hand assessment instruments. Journal of Hand Surgery, 11A: 621–623. Florence SL, Jain N, Pospichal MW, Beck PD, Sly DL, Kaas JH (1996). Central reorganization of sensory pathways following peripheral nerve regeneration in fetal monkeys. Nature, 381: 69. Hudson DA, Bolitho DG, Hodgetts K (1997). Primary epineural repair of the median nerve in children. Journal of Hand Surgery, 22B: 54–56. Imai H, Tajima T, Natsumi Y (1991). Succesful re-education of functional sensibility after median nerve repair at the wrist. Journal of Hand Surgery, 16A: 60–65. Jenkins WM, Merzenich MM, Ochs MT, Allard T, Guic-Robles E (1990). Functional reorganization of primary somatosensory cortex in adult owl
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