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ABSTRACT: This 16-year retrospective study reports the data on 456 consecutive patients with 557 peripheral nerve injuries (PNIs) between 1989 and 2004. Most patients were men (74%) and the mean age was 32.4 years. In 83% of cases the PNIs were isolated; combined lesions most commonly involved the ulnar and median nerves. Upper-limb PNIs occurred in 73.5% of cases; the ulnar nerve was most often injured, either singly or in combination. Vehicle accidents affecting the brachial plexus or radial, sciatic, facial, and peroneal nerves were the most common cause of injury. Penetrating trauma commonly affected the ulnar and median nerves; falls and gunshot wounds frequently affected the ulnar, radial, and median nerves; and sports injuries, particularly soccer, affected mainly the peroneal and tibial nerves. More than half of the brachial plexus lesions after vehicular accidents were from motorcycle crashes. Muscle Nerve 34: 785–788, 2006
PERIPHERAL NERVE INJURIES: A RETROSPECTIVE SURVEY OF 456 CASES ˜ O ARIS KOUYOUMDJIAN, MD, PhD JOA Department of Neurological Sciences, State Medical School (FAMERP), Sa˜o Jose´ do Rio Preto, Sa˜o Paulo, Brazil Accepted 31 May 2006
Peripheral nerve injuries (PNIs) are a major medical problem caused mainly by motor vehicle accidents, penetrating trauma after stabbing incidents, gun-shots, and stretching or crushing after falls. Fractures of adjacent bones are commonly associated with PNIs, such as humeral fractures with radial neuropathy.11 In addition to penetrating injury causing sharp or blunt transections/lacerations, nerves may be displaced, contused, stretched, or even partially divided, leading to neuromas or lesions in continuity.6 The incidence of PNIs is frequently underestimated and, surprisingly, few large general series have been published worldwide. Electromyography (EMG) is the most appropriate diagnostic method in the evaluation of the topography and severity of PNIs. Magnetic resonance imaging also provides useful additional information about root avulsion after traction injury to the brachial plexus. Patients should be referred for electrodiagnostic consultations within a 6-month period
Abbreviations: CMAP, compound muscular action potential; CNS, central nervous system; EMG, electromyography; MUAP, motor unit action potential; PNI, peripheral nerve injury; PSW, positive sharp wave; SNAP, sensory nerve action potential Key words: electromyography; nerve conduction studies; nerve injury; peripheral neuropathy; trauma Correspondence to: J. A. Kouyoumdjian, R. Luiz Antoˆnio Silveira 1661, 15025-020 Sa˜o Jose´ do Rio Preto, SP, Brazil; e-mail:
[email protected] © 2006 Wiley Periodicals, Inc. Published online 31 July 2006 in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/mus.20624
Short Reports
after a PNI, not so early that severe axonal degeneration is missed or too late when possible surgical benefits are minimal.12 Clinical and electrophysiological changes should be carefully followed on a monthly basis to evaluate possible early reinnervation. Patients frequently have multiple injuries and various medical specialties may be involved in their care. Thus, clinical– electrophysiological correlations may be missed or misinterpreted. The purpose of this study was to analyze data from 456 patients referred for EMG after symptomatic PNI. METHODS
From January 1989 to December 2004, 456 consecutive subjects were referred for electrodiagnostic consultation due to PNIs; only the first EMG requested after trauma was considered in this study. All subjects were symptomatic, reporting either motor (weakness) or sensory (positive or negative) symptoms. Trauma to the spine with consequent acute, subacute, or chronic radiculopathy, myelopathy, or cauda equina syndrome was not evaluated in this study. From the total of 456 cases included in the study, 557 nerve lesions were identified in the face and limbs. Data on age, gender, referring specialty, and interval between injury and first EMG were obtained. All patients underwent EMG performed by the author and the results were analyzed retrospectively. Electrophysiological involvement was graded using
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Table 1. Injury categories to peripheral nerves in 437 cases involving 534 nerve trunks. Category A Vehicle accidents B Penetrating traumas C Falls D Gun-shot wounds E Car accidents involving pedestrian F Sports G Miscellaneous Total
Cases (n) 192 90 58 37 17 12 31 437
the Seddon classification.13 Neurotmesis was diagnosed on the basis of absence of sensory nerve action potential (SNAP) or compound muscular action potential (CMAP) after distal stimulation of the affected nerve, profuse fibrillation potentials and positive sharp wave potentials (PSWs), and absence of any volitionally recruited motor unit action potentials (MUAPs). In axonotmesis, mild to profuse fibrillation potentials and PSWs were present and MUAP recruitment was reduced. Neurapraxia consisted of absent or rare fibrillation potentials and PSWs, normal MUAP morphology with reduced recruitment, and normal or reduced/absent SNAP or CMAP amplitude, depending on whether stimulation was distal or proximal to the conduction block. MUAP morphology from reinnervation was also evaluated. The brachial plexus (and lumbar and lumbosacral plexus) was considered one nerve regardless of any associated root avulsion. All terminal hand branches of the median or ulnar nerves were also considered together as median or ulnar lesions. Sensory nerve injuries were considered as neurotmesis when there was no SNAP response. Patients were classified as having single or multiple PNIs; the maximum number was five affected nerves in one patient. Descriptive statistics used included means and frequencies. The protocol for the retrospective study was approved by the institutional ethics committee. RESULTS
The 456 PNI patients constituted 3.7% of all cases referred for electrodiagnostic consultations. There were 337 men (74%) and 119 women (26%). The mean age of patients was 32.4 years, ranging from 4 to 79 years; the women were slightly older than the men (36.0 vs. 31.1 years). EMG was performed within the first 180 days after PNI in 67% of cases, between 6 and 24 months in 23.5%, and at more than 2 years after injury in 9.5%. Injuries to nerves of
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Percentage 43.9 20.6 13.3 8.5 3.9 2.7 7.1
Nerves (n) 237 105 68 48 23 16 37 534
Percentage 44.4 19.7 12.7 9.0 4.3 3.0 6.9
the upper limbs represented 73.5% of instances; to lower limbs, 21.5%; and to the face, 5%. In 2 lowerlimb cases and in another 2 involving the facial nerve, nerve injuries were bilateral. PNI categories were identified in 437 of 456 cases (95.8%), or 534 nerves (Table 1). There were 377 (83%) cases with single and 79 (17%) with multiple PNIs. Multiple nerve lesions involved two nerves in 62 cases, three nerves in 13 cases, four nerves in 3 cases, and five nerves in 1 case. The most frequent isolated nerve injuries, in descending order, were to the ulnar, brachial plexus, radial, median, peroneal, and sciatic nerves. The most common two-nerve injuries were the ulnar plus median (37.1%), peroneal plus tibial (14.5%), sciatic plus femoral (6.5%), and radial plus axillary (4.8%). The most common threenerve combination was ulnar, median, and radial. The frequencies of the most common PNIs in each trauma category are given in Table 2. Neurotmesis occurred in 41% cases, axonotmesis in 45%, and neurapraxia in 14%. There were more cases of complete denervation with peroneal nerves (65%), followed by brachial plexus (51%), suprascapular (50%), sciatic (49%), facial (48%), and posterior interosseous (47%) nerves. DISCUSSION
The limitations of this work are that the data came from a private practice in which EMG consultation occurred at a variable interval after trauma, leading to underestimates of severity. The series also includes many patients without central nervous system (CNS) lesions at the time of EMG consultation. Because patients with severe CNS involvement go to rehabilitation centers, their PNIs may well be misdiagnosed as secondary medical problems.3,4,14,15 Young and male patients are more likely to suffer PNIs. In fact, 95% of motorcycle accidents involved men and more than half of brachial
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Table 2. Percentage of individual nerve injuries in the different injury categories. Trauma A
B
C
D
E
F
G
Total number
237
105
68
48
23
16
37
Axillary Brachial plexus Facial Femoral Inferior gluteal Interosseous anterior Interosseous posterior Lumbar plexus Lumbosacral plexus Median Musculocutaneous Peroneal Radial Radial superficial Sciatic Superior gluteal Suprascapular Sural Tibial Ulnar Ulnar, cutaneous dorsal
6.8 19.8 9.3 2.1 0.8 0.0 2.1 0.0 0.4 5.1 3.0 9.3 16.5 1.3 11.4 0.8 1.3 0.4 1.7 8.0 0.0
0.0 1.9 0.0 0.0 0.0 1.0 1.9 0.0 0.0 35.2 1.0 1.9 2.9 1.0 5.7 0.0 1.0 0.0 0.0 45.7 1.0
8.8 8.8 1.5 1.5 0.0 0.0 4.4 0.0 0.0 16.2 1.5 2.9 19.1 1.5 4.4 0.0 1.5 0.0 0.0 27.9 0.0
4.2 10.4 0.0 2.1 0.0 0.0 2.1 2.1 0.0 16.7 0.0 8.3 14.6 2.1 10.4 0.0 2.1 0.0 4.2 20.8 0.0
4.3 13.0 4.3 4.3 0.0 0.0 0.0 0.0 0.0 4.3 0.0 21.7 8.7 0.0 4.3 0.0 4.3 8.7 0.0 21.7 0.0
18.8 0.0 0.0 0.0 0.0 0.0 6.3 0.0 0.0 0.0 6.3 37.5 6.3 0.0 6.3 0.0 6.3 0.0 12.5 0.0 0.0
0.0 8.1 2.7 0.0 0.0 0.0 13.5 0.0 0.0 27.0 0.0 10.8 16.2 0.0 0.0 0.0 0.0 0.0 5.4 16.2 0.0
Data expressed in percent. A, vehicle accidents (car, 116 cases; motorcycle, 63 cases); B, penetrating traumas (glass wounds, 49 cases; knife, 23 cases); C, falls (stumbling, 35 cases; over animals, 17 cases); D, gun-shot wounds; E, car–pedestrian accidents; F, sports (soccer, 8 cases); G, miscellaneous. Most frequent in each category is in bold type.
plexus injuries resulting from vehicular injury resulted from motorcycle accidents. Trauma related to sports only affected men, particularly soccer players, with peroneal nerve lesions being the most common. Most PNIs related to vehicle accidents. Almost 90% of facial nerve traumas were in this category; half of these related to motorcycle accidents, probably because a helmet was not worn. Ulnar nerve injury was the most frequent nerve lesion, occurring either in isolation or in association with median nerve involvement; it was the most common nerve injury following penetrating trauma. The association of ulnar and median nerve lesions was the most frequent due to their close anatomical relationship, specifically in the distal forearm and wrist, where penetrating trauma was very common, presumably because of the greater exposure to knife and glass wounds in manual tasks. Penetrating traumas lead to transections or lacerations; the instrument involved may be sharp, when little force is necessary to divide the nerve, or blunt, requiring a greater force for transection.6 All sural nerve lesions were caused by car accidents involving pedestrian.
Short Reports
In spite of population differences, the literature is consistent in reporting a higher incidence of PNIs of the upper limbs,2,10 although the most frequently affected nerves in earlier reports were the ulnar,1 radial,10 or digital9 nerves. For the lower limbs the most frequently affected nerves are reportedly the peroneal10 or sciatic nerves.9 Men were more frequently involved, in as much as 96%,2 83%,10 80%,1 and 74.2%9 of cases. In the different reported series, the most common trauma category was variable; penetrating trauma was responsible for 89.4% in one series,9 gun-shots for 83.9% in another,2 and motor vehicle accidents for 46% in a third series.10 Most patients were from 16 to 38 years old.2,9,10 Two studies specifically referred to PNIs and sports accidents, with the upper limbs being the most frequently affected.5,7,8 The right and left sides suffer similar incidence rates for PNIs, as reported elsewhere9,10 and supported by the present findings. EMG was performed within the appropriate period of less than 180 days after PNI in 67%. EMG later than this time may be less helpful for surgical decisionmaking.
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This work was supported by a BAP research grant from the State Medical School of Sa˜o Jose´ do Rio Preto. The author thanks David A. Hewitt for help with the English.
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8. Krivickas LS, Wilbourn AJ. Sports and peripheral nerve injuries: report of 190 injuries evaluated in a single electromyography laboratory. Muscle Nerve 1998;21:1092–1094. 9. McAllister RM, Gilbert SE, Calder JS, Smith PJ. The epidemiology and management of upper limb peripheral nerve injuries in modern practice. J Hand Surg [Br] 1996;21:4 –13. 10. Noble J, Munro CA, Prasad VS, Midha R. Analysis of upper and lower extremity peripheral nerve injuries in a population of patients with multiple injuries. J Trauma 1998;45: 116 –122. 11. Robinson LR. Traumatic injury to peripheral nerves. American Association of Neuromuscular and Electrodiagnostic Medicine. Syllabus. Assessment of traumatic nerve injuries; 2005. p 1–11. 12. Robinson LR. Traumatic injury to peripheral nerves. Muscle Nerve 2000;23:863– 873. 13. Seddon HJ. Surgical disorders of the peripheral nerves. New York: Churchill Livingstone; 1975. 14. Selecki BR, Ring IT, Simpson DA, Vanderfield GK, Sewel MF. Trauma to the central and peripheral nervous systems. Part II: A statistical profile of surgical treatment New South Wales 1977. Aust NZ J Surg 1982;52:111–116. 15. Stone L, Keenan MA. Peripheral nerve injuries in the adult with traumatic brain injury. Clin Orthop Rel Res 1988;233: 136 –144.
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