J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.45.2.181 on 1 February 1982. Downloaded from Letters 181 at the elbow gives rise to a compression aponeurosis can be causative factors of neuropathy commonly called the pronator this syndrome.5 7 8 Radiographs excluded syndrome.1-5 We studied a patient the presence of a bony supracondylar presenting this symptom-complex caused prozess. Clinically it is not always possible by a thickened bicipital aponeurosis to assess if an entrapment is caused by the compressing the median nerve. Struthers ligament or by the bicipital A 55-year-old brick-layer noted weak- aponeurosis. Our patient's symptoms ness of his left hand and numbness of the represented the common features of the thumb, second and third finger, associated entrapment of the median nerve above the with pain at the left wrist, forearm and elbow, but did not give any suggestion arm. These symptoms had an acute onset about the structure restraining it. after a day in which the patient had Some manoeuvres are described which carried heavy building material supported are supposed to be suggestive of the exact on his left forearm. When admitted, two site of the compression :27 the entrapment months later, examination revealed a by the Struthers ligament is described as slight wasting of the thenar eminence and usually associated with forearm pain of the volar aspect of the forearm. Tinel's elicited or increased during forceful sign over the median nerve at the elbow extension of the wrist, while reproduction was positive. There was weakness of the of pain by resistence to forearm supination pronator teres, flexor digitorum sublimis, and elbow flexion is considered a positive flexor digitorum profundus to the second sign for entrapment at the bicipital and third finger, flexor pollicis longus, aponeurosis. Both these manoeuvres opponens pollicis, abductor pollicis failed to demonstrate an increase of the brevis. The hand displayed a "benediction forearm pain in our patient. The electro- Fig. Angiogram showing carotid-basilar attitude" when the patient attempted to physiological findings were consistent anastomosis (long arrow) and dural make a fist. Reduction of sensation was with a compression of the nerve in the fistula (small arrow) demonstrated over the median nerve region of the elbow3 5-7 but they could Protected by copyright. distribution in the hand. Neurological not suggest the localisation of it. consistent with the hypothesis that dural examination failed to reveal any other Only the surgical exploration of the arteriovenous fistula can be due to a abnormality. The electrophysiological nerve in the antecubital fossa located the malformation, as may be the case in the study showed denervation and neurogenic structure responsible for the entrapment, present observation. Indeed, the persis- atrophy in the flexor digitorum sublimis, showing a thickened bicipital aponeurosis tence of a trigeminal artery provides some flexor digitorum profundus, abductor compressing the nervous trunk. Thvs, indirect evidence that a structural defect pollicis brevis. Distal motor latency of the thickened bicipital aponeurosis must be may have predisposed to the disruption of median nerve was 3 6 ms in the left side regarded as a rare cause of the uncommon the middle meningeal artery following a and 3-7 ms in the right side: motor con- syndrome of median nerve entrapment traumatic accident, which would have duction velocity across the elbow was above the elbow. had little effect on a normal artery. respectively 48 ms-1 and 67 ms-1. Radio- P MARTINELLI ANDREA SPISSU graphy of the chest and of the left upper AS GABELLINI Clinica delle Malattie Nervose e Mentali, extremity was normal, as were a complete M POPPI Ospedale Civile, blood count and the sedimentation rate. R GALLASSI Via Ospedale, 54, At operation, the median nerve, explored E POZZATI 09100 Cagliari in the antecubital fossa, was found to be Institute of Neurolegy, entrapped beneath a thickened bicipital University of Bologna References aponeurosis. Section of the structure Via U. Foscolo 7-40123 Bolcgna, http://jnnp.bmj.com/ exposed a flattened portion of the nerve and 2nd Neurosurgery Division 'Jayaraman A, Garofalo M, Brinker RA, in the site of the compression, and a Bellaria Hosrital, Chusid JG. Cerebral arteriovenous it. malformation and the primitive tri- swelling of the nerve trunk just above Bologna, Italy geminal artery. Arch Neurol 1977;34: The recovery of the patient was complete 96-8. in few months. The most common causes 2 Nakamura K, Tsugane R, Ito H, Obata H, of the median nerve compression at the References Narita H. Traumatic arteriovenous elbow are an hypertrophied pronator fistula of the middle meningeal vessels. teres, the passage of the nerve under both Spinner M, Spencer P. Nerve compression J Neuirosuirg 1966 ;25 :424-9. its heads, and the kinking against the lesions of the upper extremity: a clinical on September 29, 2021 by guest. 3 Markham JW. Arteriovenous fistula of the sublimis bridge.2 7 In our patient, how- and experimental review. Clin Orhtop middle meningeal artery and the greater ever, the weakness of the pronator teres 1974 ;4 :46-67. petrosal sinus. J Neurosuirg 1961 ;18: 2 muscle suggested that the entrapment of Spinner M. Injuries to the major branches 847-8. of peripheral nerves of the forearm. the nerve was indeed above the elbow. Philadelphia: WB Saunders, 1978. Pronator syndrome due to thickened Besides acute traumatic incidents, some 3 Morris HH, Peters BH. Pronator syn- bicipital aponeurosis anatomical anomalies, such as a supra- drome: clinical and electrophysiological condylar process of the humerus, the features in seven cases. J Neurol Sir: The entrapment of the median nerve Struthers ligament or a thickened bicipital Neurosurg Psychiatry 1976;39:461-4. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.45.2.181 on 1 February 1982. Downloaded from l82 Letters 4Kopell HP, Thompson WAL. Pronator to these important facts. However, it reported by Dyck and Lambert' (see syndrome. A confirmed case and its has become evident that (a) any clinical above) as having the neural type of diagnosis. N Eng J Med 1958;259:713-5. feature, including the disorder of move- Charcot-Marie-Tooth disease. Davis 5 Laha RK, Lunsford LD, Dujovny M. to essential tremor,3 and et al9 studied many kinships and quoted Lacertus fibrosus compression of the ment similar median nerve. Case report. J Neurosurg plantar ulcers of the feet,4 could be seen others from the literature in which some 1978 ;48:838-41. in both types, (b) MCV in the lower limbs affected members had MCV in the median 6 Buchthal F, Rosenfalck A, Trojaborg A. has proven to be of less value than in the nerve above 38 m/s whereas other cases Electrophysiological findings in entrap- upper limbs,3-6 (c) internodeal length is of the same kinship had MCV values ment of the median nerve at wrist and of little value in clearly distinguishing below this (see below the "inteimediate" elbow. J Neurol Neurosurg Psychiatry subtypes,5 6 (d) onion bulbs are also type, and fig 3 of their work). It is clear 1974;37:340-60. seen in the neural type.6 Gradually the that in terms of classification, the lowering 7Laha RK, Dujovny M, De Castro SC. two different Charcot-Marie- of MCV to 38 m/s in the median nerve Entrapment of median nerve by supra- concept of condylar process of the humerus. Case Tooth diseases has lost support. Patients has apparent advantages in some kin- report. J Neurosurg 1977 ;46:252-5. having an hereditary motor and sensory ships but may not be helpful in others, 8 Smith RV. Fisher RG. Struthers ligament: neuropathy with the type of inheritance, since wherever this arbitrary dividing a source of median nerve compression natural history, symptoms and signs of line is placed in terms of MCV there seem above the elbow. Case report. J Charcot-Marie-Tooth disease that Dyck to be kinships with affected members Neurosurg 1973;38:778-9. and Lambert categorise into two different above and below the line. disorders were recognised to be a single It has been claimed that although in entity. Charcot-Marie-Tooth disease subgroups Authors with the most experience with may exist, MCV is an inadequate means this disorder have put forward a genetic to define such subgroups.10 Some authors, classification of Charcot-Marie-Tooth who are keen to maintain part of the Matters arising disease based on MCV4 7 (concordance of division suggested by Dyck and Lambert conduction velocity in the upper limbs and thus classify in terms of MCV alone, Should Charcot-Marie-Tooth disease be within each family). As with the original consider the existence of widely different genetically subgrouped on motor conduc- dividing line set by Dyck and Lambert1 2 MCV in affected individuals of the sameProtected by copyright. tion velocity? there were kinships with both types, kinships as "potential flaw" in this Thomas and Calne7 lowered the limit of genetic classification of the disease.4 Sir: Based on clinical, electrophysio- MCV in the median nerve to 38 m/s, Designating such findings as a "potential logical and morphological studies Dyck thus maintaining the division of the flaw" ignores the facts that (a) in few and Lambert divided patients with disorder into two genetically different families have electrophysiological studies Charcot-Marie-Tooth disease into what types in terms of MCV. However, been made in several affected members, they considered to be two different Harding and Thomas4 have written that and (b) when such studies are available disorders, which were reported separately in their study there were examples where some have shown widely different MCV in two papers.1 2 One was denoted hyper- MCV in the affected individuals fell "out in the upper limbs in affected members.