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Partial lacerations of median and ulnar nerves
Partial lacerations of median and ulnar nerves Twelve patients with sharp distal partial median and ulnar nerve lacerations were treated within 2 weeks of injury by end-to-end repair of the lacerated fascicular groups. After an average follow-up of 21 months, the results, based on the British Medical Research Council Rating Scale, were good: S = 3.81 and M = 4.0 (normal: S = 4.0 and M = 5.0). The function of the originally intact fascicular group s did not deteriorate. We suggest that nerve repair of partially lacerated fascicular groups is a reliable treatment method that results in good return of sensory and motor function and does not harm adjacent intact fascicular groups. (J HAND SURG 1991;16A:207-10.)
Lawrence C. Hurst, MD, Andrew Dowd, MD, Steven P. Sampson, MD, and Marie A. Badalamente, PhD, Stony Brook, N.Y.
It
has been reported that 60% of wartime nerve lacerations do not completely divide the nerve ." 2 However, in civilian practice our experience suggests that partial lacerations are uncommon . Review of the English -language literature shows no article devoted solely to the problem of partial nerve laceration. A review of the general nerve injury literature disclosed only brief comments on partial lacerations and gave no clear consensus regarding appropriate treatment. Observation alone, nerve wrapping, completing the laceration before repair, suturing of the lacerated portion alone, or nerve grafting of the transected portion have all been recomm ended. 3· 10 Th is retrospective study was undertaken to assess the value of end-to-end repair of the lacerated fascicular groups. Materials Between 1981 and 1987, 12 patients with either median or ulnar distal partial nerve lacerations were treated by early microsurgical repair ofthe lacerated fascicular groups (Table I). During the same time interval, 75 complete nerve lacerations were repaired , and 1975 From the Department of Orthopaedic Surgery, SUNY at Stony Brook School of Medicine, Health Sciences Center T-18, Stony Brook, N.Y. Received for publication Dec. 19, 1989; accepted in revised form June 5, 1990. No benefits in any form have been received or will be received from a commerci al party related directly or indirectly to the subject of this article. Reprint requests: Lawrence C. Hurst , MD. Associate Professor. Departrnent of Orthopaedic Surgery, SUNY at Stony Brook School of Medicine , Health Sciences Center T-18, Stony Brook, NY 11794. 3/1/23467
other hand procedures were performed at our hand center. Therefore, partial nerve repairs represent 0.6% of all operations and only 14% of the nerve repairs. The group with partial lacerations had II males and I female. All patients sustained sharp (knife or glass) traumatic partial lacerations. The average age was 23 years (range, 4 to 44 years). There were 10 partial lacerations of the median nerve and 2 partial lacerations of the ulnar nerve. The lacerations of the median nerve were located at the elbow (n = 1), distal forearm (n = 5), and wrist (n = 4). The ulnar nerve lacerations were located at the elbow (n = 1) and in the hand (n = I) . In all patients, the preoperative clinical examination showed an easily detectable partial nerve laceration with functional impairment. When seen initially all 12 patients had partial sensory loss and 6 patients had motor loss. The interval between injury and nerve repair averaged 14 days (range, 0 to 55 days). The estimated percentage of the nerve laceration at surgery averaged 49% (range, 10% to 75%). Follow-up averaged 21 months (range, 6 months to 4Y2 years). Surgical technique With the aid of loupe magnification, the traumatic wounds were extended proximally and distally. Once the median or ulnar partial lacerations was identified, the dissection was continued with the operative microscope and microsurgical instruments (Fig. I, A). In cases done within a week, the junction between the lacerated fascicular groups and intact fascicular groups could easily be determined at the level of the laceration (Fig. I, A [arrow]). The proximal lacerated fascicular groups were then separated as a unit from the intact groups by dissecting the internal epineural planes (Fig. 1, B). An identical dissection was then done distally THE JOURNALOF HAND SURGERY
207
The Journal of
208
HAND SURGERY
Hurst et al,
Table I. Patients with partial median and ulnar nerve lacerations Patient R. R. N.M. S. S. P. H. E. C. C.M. D. J. L. P. M.P. D. B. . J. A. A.M.
Interval-injury to surgery (days)
Age 37 15 31 27 21 29 15 23 9 44 4 22 Average age
=
23
M M M M M M M M F M M M II'Males I Female
41 37 I 55 0 18 I 6 3 I 0 9 Average interval = 14 days
Sensory result : BMRC scale 3.5 4 .0 3.0 4.0 3.5 3.75 4 .0 4.0 4.0 4 .0 4 .0 4 .0 Average sensory = 3.81
Motor result: BMRC scale 4 .0 5.0 5.0 4.0 3.0 3.0 5.0 5.0 5.0 5.0 5.0 3.0 Average rnotor = 4.0*
Maximum-follow-up (rna)
24 8 18 6 37 8 36 12 16 25 54 12 Average followup = 21 rna
'The average motor BMRCrating scale is based on the six patientswho had preoperative motor deficits .
(Fig. 1, C). The vessels on the external and internal epineurium were used to guide the dissection. In injuries seen after 1 week, the dissection was started 1 to 2 ern proximal to the laceration (Fig . 1, B [double arrow)). The external epineurium was opened and the interval between the lacerated and intact fascicular groups was enlarged. The fascicular groups were dissected as a unit into the early neuroma. The distal fascicular groups were similarly dissected. These dissections also defined the intact fascicular groups (Fig. 1, C).
Next, tension between the ends of the cut fascicular groups was assessed . In some cases, wrist flexion controlled all or part of the tension . If needed, the remaining tension was controlled by making a loop in the intact fascicular groups and holding it with a single 8-0 nylon suture in the external epineurium (Fig. 1, D). This made approximation and microsurgical suturing of the cut fascicular groups easier. Before repair, the proximal 2 to 4 rnm neuroma and distal 2 to 4 mrn glioma were resected .. The resultant true defect was usually less -than I em, although the functional gap might appear slightly larger because of fascicular elas-
ticity." Next, fascicular matching was done by comparing the distal and proximal fascicular size and orientation and by observing the epineural vessels . Rotatory alignment was determined by examining the connections of the lacerated fascicular groups to the intact groups. The repair was done using 10-0 nylon external epineuria1 sutures and an occasional internal 10-0 epineurial suture (Fig. 1, E). In four (33%) patients the 8-0 loop suture was left in place. It was removed after repair in two patients and was not used in six patients (Fig. 1, F). With experience it became apparent that clastic gap could often be controlled with wrist flexion alone. After operation, the wrist was placed in a cast or splinted in flexion for 4 weeks.
Results The sensory and motor recovery of all patients was evaluated according to Moberg's modification of the British Medical Research Council (BMRC) Rating Scale ." The intact fascicular nerve group s of each patient were evaluated separately from their repaired fascicular groups. The intact fascicular groups that were functionally normal before operation were also functionally normal at the end of the study (5 = 4.0 and M = 5.0) (Fig. 2). There was no sign of deterioration of the originally intact fascicular groups with time . According t? Moberg's sensory scale (good, fair, poor, bad) the results of repaired fascicular groups were eight good , one fair, three poor, and no bad results. The sensory result using the Moberg modification of the (BMRC) scale" averaged 5 = 3.81 (range, 3 to 4). Eight (66%) patients had 10 mm two-point discrimination or better, and 10 (83%) patients had 15 mm twopoint discrimination or better. The motor result in those six patients who had preoperative motor loss averaged M = 4.0 (Fig. 2). To assess the effect of the interval between injury and operation, all patients (n = 7) operated on within 1 week (average, 1.7 days; range, 0 to 6 days) were compared by their sensory results to the patients (n = 5) operated on after 1 week (average, 32 days, range , 9 to 55 days). The BMRC sensory grade for the repairs done within 1 week was 5 = 3.78. For repairs done after 1 week 5 = 3.85. This difference was not statistically significant (p = 0.37). To assess the potential detrimental effect of a permanent loop suture, the group (n = 4) with a permanent loop suture was compared with the group (n = 8) with no loop suture . When the loop was left in place the BMRC sensory result for the repaired fascicular nerve groups was 5 = 3.63. When the loop was not used or removed the BMRC sensory grade was 5 = 3.90. This difference was not statistically significant (p = 0.39). The
Vol. 16A, No.2 March 1991
Partial lacerations of median and ulnar nerves
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Fig. 1. Repair of partial median nerve laceration. (A), Approximately a 50% laceration. Arrow shows where dissection was started when the operation was done within I week. (8), Proximal fascicular groups mobilized. Double arrow shows where dissection was started when operation was done after I week. (e), Both lacerated fascicular groups mobilized, intact fascicular groups identified, and neurolysis done if needed. Neuroma and glioma have been excised. (D), Loop suture (8-0 nylon) controlling tension during repair. Suture in external and internal epineurium. (E), Repair completed with 10-0 nylon suture. (F), Loop suture removed. Wrist flexion used to control tension.
intact fascicular groups remained totally functional in both the loop group and the no loop groups. Only six patients had preoperative motor deficiencies. Therefore, the motor results were not used to assess the effect of the preoperative interval or the permanent loop suture. The only complication occurred in a patient who removed his cast 5 days after the operation and hyperextended his wrist. His initial result was S' = 0 and M = O. He had a secondary repeat repair. His final result was S = 3.5 and M = 3.0. Discussion The treatment alternatives for partial nerve lacerations are variable. Early authors recommended resection of the entire injured area and repair of the whole nerve if 50% or more of the nerve was cut or if the intact portion was "functionally unimportant. "2. 7. 9 Others have suggested leaving the injury alone, partie-
Fig. 2. Graphs showing average BMRC results. Bottom graph: Sensory results in intact and repaired fascicular nerve groups. Top graph: Motor results in intact and repaired fascicular nerve groups.
ularly if it was proximal, if less than one third of the nerve was cut, or if it was seen late." 7,.8 Seddon, Edshage and Millesi" 7.8 have recommended nerve grafting for treatment of partial nerve lacerations. The reason for the grafting has not always been the size of the defect. Grafting was also done to avoid jeopardizing the function of intact fascicles by kinking them.' Seddon" believed grafting was simpler and less awkward. Without the routine use of the operative microscope this might be true. Sunderland's? interfascicular connections might also be considered a hindrance to the type of dissection needed for a direct partial repair. However, Jabaley and Williams 13. 14 have clearly shown that these connections are usually between fascicles and not between the distal fascicular groups that are at the level of the surgical dissection. Repair of the lacerated fascicular groups only, if done early and with distal injuries, has been suggested by Sunderland? and others.": s. 6, 10 While advocating endto-end repair of the cut fascicular groups in early sharp injuries, these surgeons have generally been opposed to the loop suture. However, none of these authors have supported their opinion with published data. The only study that has suggested that a partial nerve laceration can be harmful to the intact portion of the nerve is an animal study of lateral neuromas.' Partial lacerations were made in primate peroneal nerves. Each laceration
210
The Journal of HAND SURGERY
Hurst et al.
caused a 50% to 75% decrease in the amplitude of the nerve action potential (NAP). The percentage of crosssectional area transected was not reported. The velocity and amplitude in the intact part of the nerve was studied over time. It is important to note that in this study the nerves were 1/01 repaired. The study showed a deterioration in function of the intact fascicles with time. The results of this retrospective clinical study indicate that if median and ulnar distal partial lacerations are repaired within 2 months, the results in the repaired fascicular groups wiII be good and entrapment neuropathy wiII not develop in the intact fascicular groups. Our average sensory grade of 3.81 and motor grade of 4.0 after partial nerve repairs compare favorably to the civilian studies of whole nerve repair recently reviewed by Dellon and Mackinnon. IS From their data the distal average ulnar and median sensory results can be calculated to be S = 3.0 and S = 3.06, respectively. The average distal ulnar and median motor results were M = 2.96 and M = 3.33, respectively. Although operative nerve conduction studies have been suggested as an adjunct for evaluating which fascicular groups are intact and which are not, 1.2.10.16 we agree with Lundborg" that usually the surgeon can make an accurate decision by microscopic observation alone. With a chronic large lateral neuroma-incontinuity, nerve action potential evaluation may be helpful if the equipment and personnel familiar with its operation are available during the surgical exploration. In summary, the fascicular groups of the distal median and ulnar nerves can be easily separated by the internal epineurial planes after sharp partial lacerations. After neuroma resection the true nerve defect is tiny (less than 4 to 8 mm) and the functional gap caused by fascicular elasticity is usually small. This gap can be dealt with by a combination of wrist flexion, a temporary loop suture, or possibly a suture jig. 18. By visualizing the partial nerve laceration with an operative microscope, a reliable judgement of the intact versus lacerated fascicular groups can be made without the evaluation of nerve action potentials. In four patients, this study has also shown that a permanent loop suture is not harmful. If tension caused by the anatomic defect created by neuroma resection or if the artificial gap, caused by fascicular elasticity, cannot be controlled by joint flexion then a loop suture should be used. Currently, we frequently use the loop suture to temporarily control fascicular elasticity while group fascicular repairs are performed. In most cases (>80%), the loop is removed after the repair is completed. Our followup has shown that the intact fascicular groups are not harmed by the adjacent repair. Finally, the results in the repaired fascicular groups are similar to those re-
ported by others after complete transection and repair of distal median and ulnar nerves. REFERENCES I. Kline D, Hackett E, May PRo Partial nerve laceration evaluated by evoked potentials. J Surg Res 1970;10:8190. 2. Kline D. Evaluation of the neuroma-in-continuity. In: OrnerG, Spinner M, ed. Managementof peripheral nerve problems. Philadelphia: WB Saunders, 1980:451-61. 3. Edshage S. In: Jewett D, McCarroll H, ed. Nerve repair and regeneration its clinical and experimental basis. St. Louis: The CV Mosby Company, 1980:279-83. 4. Millesi H. The current state of peripheral nerve surgery in the upper limb (in French and English). Ann Chir Main 1984;3:18-34. 5. Hooper G, Kuczynski K. Nerve injuries. In: Lamb D, Hooper G, Kiczynski K, cd. The practice of hand surgery, Oxford: Blackwell Scientific, 1989:196-217. 6. Lovett W, McCalla M. Nerve injuries: management and rehabilitation. Orthop Clin North Am 1983;14:767-78. 7. Sunderland S. Nerve and nerve injuries. 2nd ed. New York: Churchill Livingstone, 1978:36, 140, 190, 206-8, 470, 489, 522-4, 629. 8. Seddon H. Surgical disorders of the peripheral nerves, 2nd cd. New York: Churchill Livingstone, 1975:276-80, 298. 9. Seddon H, Riddoch G. Peripheral nerve injuries.(i) surgery of the peripheral nerves. History of the second world war. London: Her Majesty's Stationery Office, 1953:51733. 10. Williams H, Terzis J. Single fascicular recordings: an intraoperative diagnostic tool for the management of peripheral nerve lesions. Plast Reconstr Surg 1976;57: 562-9. II. Stevens W, Hall J, Young V, Weeks P. When should nerve gaps be grafted? An experimental study in rats. Plast Reconstr Surg 1985;75:707-13. 12. Orner G. The evaluation of clinical results following peripheral nerve suture. In: Orner G, Spinner M, ed. Management of peripheral nerve problems. Philadelphia: WB Saunders, 1980:431-42. 13. Jabaley ME, Wallace W, Heckler F. Internal topography of major nerves of the forearm and hand: a current view. J HAND SURG 1980;5:1-18. 14. Williams H, Jabaley M. The importance of internal anatomy of the peripheral nerves to nerve repair in the forearm and hand. Hand Clinics 1986;2:689-707. 15. Mackinnon S, Dellon A. Surgery of the peripheral nerve. 1st ed. New York: Thieme Medical, 1988:115-29. 16. Terzis J, Faibisoff B, Williams H. The nerve gap: suture under tension vs graft. Plast Reconstr Surg 1975;56:16670. 17. Lundborg G. Nerve injury and repair. New York: Churchill Livingstone, 1988:197-213. 18. Austin R, Walker F. A suture-jig for peripheral nerve repair. J Roy Col Surg Edin 1986;31(1):44-9.
Lawrence C. Hurst, MD, Andrew Dowd, MD, Steven P. Sampson, MD, and Marie A. Badalamente, PhD, Stony Brook, N.Y.
It
has been reported that 60% of wartime nerve lacerations do not completely divide the nerve ." 2 However, in civilian practice our experience suggests that partial lacerations are uncommon . Review of the English -language literature shows no article devoted solely to the problem of partial nerve laceration. A review of the general nerve injury literature disclosed only brief comments on partial lacerations and gave no clear consensus regarding appropriate treatment. Observation alone, nerve wrapping, completing the laceration before repair, suturing of the lacerated portion alone, or nerve grafting of the transected portion have all been recomm ended. 3· 10 Th is retrospective study was undertaken to assess the value of end-to-end repair of the lacerated fascicular groups. Materials Between 1981 and 1987, 12 patients with either median or ulnar distal partial nerve lacerations were treated by early microsurgical repair ofthe lacerated fascicular groups (Table I). During the same time interval, 75 complete nerve lacerations were repaired , and 1975 From the Department of Orthopaedic Surgery, SUNY at Stony Brook School of Medicine, Health Sciences Center T-18, Stony Brook, N.Y. Received for publication Dec. 19, 1989; accepted in revised form June 5, 1990. No benefits in any form have been received or will be received from a commerci al party related directly or indirectly to the subject of this article. Reprint requests: Lawrence C. Hurst , MD. Associate Professor. Departrnent of Orthopaedic Surgery, SUNY at Stony Brook School of Medicine , Health Sciences Center T-18, Stony Brook, NY 11794. 3/1/23467
other hand procedures were performed at our hand center. Therefore, partial nerve repairs represent 0.6% of all operations and only 14% of the nerve repairs. The group with partial lacerations had II males and I female. All patients sustained sharp (knife or glass) traumatic partial lacerations. The average age was 23 years (range, 4 to 44 years). There were 10 partial lacerations of the median nerve and 2 partial lacerations of the ulnar nerve. The lacerations of the median nerve were located at the elbow (n = 1), distal forearm (n = 5), and wrist (n = 4). The ulnar nerve lacerations were located at the elbow (n = 1) and in the hand (n = I) . In all patients, the preoperative clinical examination showed an easily detectable partial nerve laceration with functional impairment. When seen initially all 12 patients had partial sensory loss and 6 patients had motor loss. The interval between injury and nerve repair averaged 14 days (range, 0 to 55 days). The estimated percentage of the nerve laceration at surgery averaged 49% (range, 10% to 75%). Follow-up averaged 21 months (range, 6 months to 4Y2 years). Surgical technique With the aid of loupe magnification, the traumatic wounds were extended proximally and distally. Once the median or ulnar partial lacerations was identified, the dissection was continued with the operative microscope and microsurgical instruments (Fig. I, A). In cases done within a week, the junction between the lacerated fascicular groups and intact fascicular groups could easily be determined at the level of the laceration (Fig. I, A [arrow]). The proximal lacerated fascicular groups were then separated as a unit from the intact groups by dissecting the internal epineural planes (Fig. 1, B). An identical dissection was then done distally THE JOURNALOF HAND SURGERY
207
The Journal of
208
HAND SURGERY
Hurst et al,
Table I. Patients with partial median and ulnar nerve lacerations Patient R. R. N.M. S. S. P. H. E. C. C.M. D. J. L. P. M.P. D. B. . J. A. A.M.
Interval-injury to surgery (days)
Age 37 15 31 27 21 29 15 23 9 44 4 22 Average age
=
23
M M M M M M M M F M M M II'Males I Female
41 37 I 55 0 18 I 6 3 I 0 9 Average interval = 14 days
Sensory result : BMRC scale 3.5 4 .0 3.0 4.0 3.5 3.75 4 .0 4.0 4.0 4 .0 4 .0 4 .0 Average sensory = 3.81
Motor result: BMRC scale 4 .0 5.0 5.0 4.0 3.0 3.0 5.0 5.0 5.0 5.0 5.0 3.0 Average rnotor = 4.0*
Maximum-follow-up (rna)
24 8 18 6 37 8 36 12 16 25 54 12 Average followup = 21 rna
'The average motor BMRCrating scale is based on the six patientswho had preoperative motor deficits .
(Fig. 1, C). The vessels on the external and internal epineurium were used to guide the dissection. In injuries seen after 1 week, the dissection was started 1 to 2 ern proximal to the laceration (Fig . 1, B [double arrow)). The external epineurium was opened and the interval between the lacerated and intact fascicular groups was enlarged. The fascicular groups were dissected as a unit into the early neuroma. The distal fascicular groups were similarly dissected. These dissections also defined the intact fascicular groups (Fig. 1, C).
Next, tension between the ends of the cut fascicular groups was assessed . In some cases, wrist flexion controlled all or part of the tension . If needed, the remaining tension was controlled by making a loop in the intact fascicular groups and holding it with a single 8-0 nylon suture in the external epineurium (Fig. 1, D). This made approximation and microsurgical suturing of the cut fascicular groups easier. Before repair, the proximal 2 to 4 rnm neuroma and distal 2 to 4 mrn glioma were resected .. The resultant true defect was usually less -than I em, although the functional gap might appear slightly larger because of fascicular elas-
ticity." Next, fascicular matching was done by comparing the distal and proximal fascicular size and orientation and by observing the epineural vessels . Rotatory alignment was determined by examining the connections of the lacerated fascicular groups to the intact groups. The repair was done using 10-0 nylon external epineuria1 sutures and an occasional internal 10-0 epineurial suture (Fig. 1, E). In four (33%) patients the 8-0 loop suture was left in place. It was removed after repair in two patients and was not used in six patients (Fig. 1, F). With experience it became apparent that clastic gap could often be controlled with wrist flexion alone. After operation, the wrist was placed in a cast or splinted in flexion for 4 weeks.
Results The sensory and motor recovery of all patients was evaluated according to Moberg's modification of the British Medical Research Council (BMRC) Rating Scale ." The intact fascicular nerve group s of each patient were evaluated separately from their repaired fascicular groups. The intact fascicular groups that were functionally normal before operation were also functionally normal at the end of the study (5 = 4.0 and M = 5.0) (Fig. 2). There was no sign of deterioration of the originally intact fascicular groups with time . According t? Moberg's sensory scale (good, fair, poor, bad) the results of repaired fascicular groups were eight good , one fair, three poor, and no bad results. The sensory result using the Moberg modification of the (BMRC) scale" averaged 5 = 3.81 (range, 3 to 4). Eight (66%) patients had 10 mm two-point discrimination or better, and 10 (83%) patients had 15 mm twopoint discrimination or better. The motor result in those six patients who had preoperative motor loss averaged M = 4.0 (Fig. 2). To assess the effect of the interval between injury and operation, all patients (n = 7) operated on within 1 week (average, 1.7 days; range, 0 to 6 days) were compared by their sensory results to the patients (n = 5) operated on after 1 week (average, 32 days, range , 9 to 55 days). The BMRC sensory grade for the repairs done within 1 week was 5 = 3.78. For repairs done after 1 week 5 = 3.85. This difference was not statistically significant (p = 0.37). To assess the potential detrimental effect of a permanent loop suture, the group (n = 4) with a permanent loop suture was compared with the group (n = 8) with no loop suture . When the loop was left in place the BMRC sensory result for the repaired fascicular nerve groups was 5 = 3.63. When the loop was not used or removed the BMRC sensory grade was 5 = 3.90. This difference was not statistically significant (p = 0.39). The
Vol. 16A, No.2 March 1991
Partial lacerations of median and ulnar nerves
pr;x:~ \(:':-':::~:'::":'
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209
FOLLOW-UP MOTOR SCORES 5
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a: 0 en
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Fig. 1. Repair of partial median nerve laceration. (A), Approximately a 50% laceration. Arrow shows where dissection was started when the operation was done within I week. (8), Proximal fascicular groups mobilized. Double arrow shows where dissection was started when operation was done after I week. (e), Both lacerated fascicular groups mobilized, intact fascicular groups identified, and neurolysis done if needed. Neuroma and glioma have been excised. (D), Loop suture (8-0 nylon) controlling tension during repair. Suture in external and internal epineurium. (E), Repair completed with 10-0 nylon suture. (F), Loop suture removed. Wrist flexion used to control tension.
intact fascicular groups remained totally functional in both the loop group and the no loop groups. Only six patients had preoperative motor deficiencies. Therefore, the motor results were not used to assess the effect of the preoperative interval or the permanent loop suture. The only complication occurred in a patient who removed his cast 5 days after the operation and hyperextended his wrist. His initial result was S' = 0 and M = O. He had a secondary repeat repair. His final result was S = 3.5 and M = 3.0. Discussion The treatment alternatives for partial nerve lacerations are variable. Early authors recommended resection of the entire injured area and repair of the whole nerve if 50% or more of the nerve was cut or if the intact portion was "functionally unimportant. "2. 7. 9 Others have suggested leaving the injury alone, partie-
Fig. 2. Graphs showing average BMRC results. Bottom graph: Sensory results in intact and repaired fascicular nerve groups. Top graph: Motor results in intact and repaired fascicular nerve groups.
ularly if it was proximal, if less than one third of the nerve was cut, or if it was seen late." 7,.8 Seddon, Edshage and Millesi" 7.8 have recommended nerve grafting for treatment of partial nerve lacerations. The reason for the grafting has not always been the size of the defect. Grafting was also done to avoid jeopardizing the function of intact fascicles by kinking them.' Seddon" believed grafting was simpler and less awkward. Without the routine use of the operative microscope this might be true. Sunderland's? interfascicular connections might also be considered a hindrance to the type of dissection needed for a direct partial repair. However, Jabaley and Williams 13. 14 have clearly shown that these connections are usually between fascicles and not between the distal fascicular groups that are at the level of the surgical dissection. Repair of the lacerated fascicular groups only, if done early and with distal injuries, has been suggested by Sunderland? and others.": s. 6, 10 While advocating endto-end repair of the cut fascicular groups in early sharp injuries, these surgeons have generally been opposed to the loop suture. However, none of these authors have supported their opinion with published data. The only study that has suggested that a partial nerve laceration can be harmful to the intact portion of the nerve is an animal study of lateral neuromas.' Partial lacerations were made in primate peroneal nerves. Each laceration
210
The Journal of HAND SURGERY
Hurst et al.
caused a 50% to 75% decrease in the amplitude of the nerve action potential (NAP). The percentage of crosssectional area transected was not reported. The velocity and amplitude in the intact part of the nerve was studied over time. It is important to note that in this study the nerves were 1/01 repaired. The study showed a deterioration in function of the intact fascicles with time. The results of this retrospective clinical study indicate that if median and ulnar distal partial lacerations are repaired within 2 months, the results in the repaired fascicular groups wiII be good and entrapment neuropathy wiII not develop in the intact fascicular groups. Our average sensory grade of 3.81 and motor grade of 4.0 after partial nerve repairs compare favorably to the civilian studies of whole nerve repair recently reviewed by Dellon and Mackinnon. IS From their data the distal average ulnar and median sensory results can be calculated to be S = 3.0 and S = 3.06, respectively. The average distal ulnar and median motor results were M = 2.96 and M = 3.33, respectively. Although operative nerve conduction studies have been suggested as an adjunct for evaluating which fascicular groups are intact and which are not, 1.2.10.16 we agree with Lundborg" that usually the surgeon can make an accurate decision by microscopic observation alone. With a chronic large lateral neuroma-incontinuity, nerve action potential evaluation may be helpful if the equipment and personnel familiar with its operation are available during the surgical exploration. In summary, the fascicular groups of the distal median and ulnar nerves can be easily separated by the internal epineurial planes after sharp partial lacerations. After neuroma resection the true nerve defect is tiny (less than 4 to 8 mm) and the functional gap caused by fascicular elasticity is usually small. This gap can be dealt with by a combination of wrist flexion, a temporary loop suture, or possibly a suture jig. 18. By visualizing the partial nerve laceration with an operative microscope, a reliable judgement of the intact versus lacerated fascicular groups can be made without the evaluation of nerve action potentials. In four patients, this study has also shown that a permanent loop suture is not harmful. If tension caused by the anatomic defect created by neuroma resection or if the artificial gap, caused by fascicular elasticity, cannot be controlled by joint flexion then a loop suture should be used. Currently, we frequently use the loop suture to temporarily control fascicular elasticity while group fascicular repairs are performed. In most cases (>80%), the loop is removed after the repair is completed. Our followup has shown that the intact fascicular groups are not harmed by the adjacent repair. Finally, the results in the repaired fascicular groups are similar to those re-
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