Compression neuropathy of the palmar cutaneous branch of the median nerve by the antebrachial fascia

COMPRESSION NEUROPATHY OF THE PALMAR CUTANEOUS BRANCH OF THE MEDIAN NERVE BY THE ANTEBRACHIAL FASCIA N. SEMER, C. CRIMMINS and N. FORD JONES

From the Division of Plastic Surgery and the Department of Orthopaedic Surgery, University of California, Los Angeles, USA An isolated compression neuropathy of the palmar cutaneous branch of the median nerve is described in a woman who presented with a small tender mass over the anterior aspect of her distal forearm and complete numbness over the thenar eminence. Surgical exploration revealed thickening of the palmar cutaneous nerve as it passed upwards through the antebrachial fascia on the ulnar aspect of the flexor carpi radialis tendon. Neurolysis of two separate fascicles of the palmar cutaneous branch of the median nerve and excision of a window of antebrachiai fascia resulted in complete return of sensation over the thenar eminence.

Journal of Hand Surgery (British and European Volume, 1996) 21B: 5:666 667 The palmar cutaneous branch of the median nerve provides sensation to the thenar eminence and the proximal radial aspect of the palm. It arises from the median nerve in the distal third of the forearm, courses superficially along the ulnar side of the flexor carpi radialis (FCR), and then enters a short tunnel in the flexor retinaculum. The nerve can easily be injured in wrist lacerations or iatrogenically from surgical incisions (Taleisnik, 1973). There have been rare reports of compression neuropathies involving this nerve (A1-Qattan and Robertson, 1993; Buckmiller and Rickard, 1987; Gessini et al, 1983; Haskin, 1994; Shimizu et al, 1988; Stellbrink, 1972). An isolated entrapment of this sensory

Fig 1

nerve by the antebrachial fascia without concomitant carpal tunnel syndrome is described. CASE R E P O R T

A healthy 39-year-old right-handed woman developed a small, painful mass over the palmar aspect of her distal right forearm 3 months prior to presentation. There was no history of trauma to the extremity. The mass resolved spontaneously, but then recurred. She complained of pain, especially on wrist extension, and numbness over the thenar eminence. On physical examination, there was a small, approximately 0.75 cm, discrete mass on

Two separate fascicles of the palmar cutaneous branch of the median nerve are seen after release of the antebrachial fascia. 666

P A L M A R CUTANEOUS B R A N C H O F M E D I A N NERVE

the anterior aspect of the distal forearm and absent sensation over the thenar eminence. There were no concomitant symptoms of carpal tunnel syndrome. Surgical exploration revealed a slightly swollen superficial palmar branch of the median nerve tethered by thickened antebrachial fascia and the FCR tendon. The mass represented the coalescence of these three structures as the palmar cutaneous branch penetrated upwards through the antebrachial fascia. Two separate fascicles could be dissected from the fascia and FCR using loupe magnification, and neurolysis was performed (Fig 1). Postoperatively, the pain in her forearm resolved within 2 weeks of the operation and by 5 months she had complete return of normal sensation over the thenar eminence.

DISCUSSION

Entrapment neuropathy of the palmar cutaneous branch of the median nerve can cause significant symptoms which are quite troublesome to the patient. This entity has only been documented in six previous case reports. In six patients, a palmar wrist ganglion was implicated as the causative factor (A1-Qattan and Robertson, 1993; Buckmiller and Rickard, 1987; Gessini et al, 1983; Haskin, 1994), and in one patient the nerve was compressed by an atypical palmaris longus muscle (Stellbrink, 1972). In one patient with concomitant carpal tunnel syndrome, the fascia of the flexor digito-

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rum superficialis caused compression of the palmar sensory branch (Shimizu et al, 1988). The patient described in this report had isolated entrapment of the palmar cutaneous branch of the median nerve due to encasement by both a thickened antebrachial fascia and the FCR; this has not been previously reported. Neurolysis of the nerve from these structures and wide excision of the antebrachial fascia led to complete resolution of her symptoms. References AL-QATTAN M M and R O B E R T S O N G A (1993). Entrapment neuropathy of the palmar cutaneous nerve within its tunnel. Journal of Hand Surgery, 18B: 4 6 5 4 6 6 . B U C K M I L L E R J F and R I C K A R D T A (1987). Isolated compression neuropathy of the palmar cutaneous branch of the median nerve. Journal of Hand Surgery, 12A: 97-99. GESSINI L, J A N D O L O B, P I E T R A N G E L I A and SENESE A (1983). Compression of the palmar cutaneous nerve by ganglions of the wrist. Journal of Neurosurgical Science, 27: 241-243. HASKIN J S (1994). Ganglion-related compression neuropathy of the palmar cutaneous branch of the median nerve: a report of two cases. Journal of H a n d Surgery 19A: 827-828. SHIMIZU K, IWASAKI R, H O S H I K A W A H and Y A M A M U R O T (1988). Entrapment neuropathy of the palmar cutaneous branch of the median nerve by the fascia of flexor digitorum superficialis. Journal of H a n d Surgery, 13A: 581-583. STELLBRINK G (1972). Compression of the palmar branch of the median nerve by atypical palmaris longus muscle. Handchirurgie, 4 : 1 5 5 - 1 5 7 (in German). TALEISNIK J (1973). The palmar cutaneous branch of the median nerve and the approach to the carpal tunnel. An anatomical study. Journal of Bone and Joint Surgery, 55A: 1212-1217.

Received: 6 July 1995 Accepted after revision: 25 March 1996 N. F. Jones MD, 200 UCLA Medical Plaza, Los Angeles, California 90095-6907,USA. © 1996The British Society for Surgery of the Hand