Unusual presentation of the wartenberg syndrome as writers cramp

A 57 year old male, clerk by profession, presented to us with complaints of right thumb pain with limitations of movements at thumb, thinning of the thumb and deformity of nail. The patient had right thumb pain in doing his clerical work i.e. writing, holding files etc. typical of writers cramp. He started to experience disturbance in sleep due to pain that was radiating over the radial aspect of the hand & progressively increasing. On local examination, there was atrophy of the pulp of the thumb (Fig. 1) with relative paleness), clubbing of the nail, hardly any movement at interphalangeal joint (active or passive), swelling over the 1st MCP joint, tender with crepitus on movement, with no redness or local rise of temperature. Routine blood and urine investigations were within normal limits. X-ray of the thumb showed osteopenia of the metacarpal & phalanges, with metaphysial cystic lesion of the 1st metacarpal distal end & flattening of 1st metacarpal head. There was narrowing of the 1st MCP joint space with few osteophytes around 1st MCP joint (Fig. 2). Hence to rule out a possible vascular pathology, investigation such as colour doppler, peripheral oxygen saturation were done. A trial of peripheral vasodilator gave no relief to the patient. The MRI of hand, forearm and arm, rule out any space occupying lesion causing compression over the anterior interosseous nerve. The nerve conduction study and electromyography also showed normal pattern. Considering the severity of pain and low threshold for stimulation. Thus a pathology of superficial radial nerve was sought. Hence a trial block of superficial radial nerve at mid forearm level was given. With immediate effect the patient's pain was relieved and his movements at thumb were painless. A review of literature located one article with a case series of wartenberg syndrome, initially presented as writer's cramp. With this idea the exploration of superficial radial nerve was planned. Intra-operatively no space occupying lesion was found. Instead the superficial radial nerve was entrapped near its point of exit beneath Brachioradialis's tendinous portion (Fig. 3). The nerve was explored till 2/3rd of the forearm and was freed from the surrounding. Because of the 1st MP joint advance arthritis arthrodesis of this joint was done in same sitting (Fig. 4). The patient was given 4 weeks of thumb spica and later only MP joint immobilization was done using Aluform splint till union. At one year followup the patient is pain-free with negligible improvement in thumb appearance (Fig. 5.1, 5.2)