Ulnar neuropathy at the elbow in diamond assorters.

Unilateral ulnar neuropathy at the elbow was detected in 12 men employed as diamond assorters. Asymptomatic diamond assorters were studied as controls. In the symptomatics, the ulnar neuropathy was restricted to the hand which held the eye-glass used for inspecting the diamonds. Electrophysiological studies using several parameters revealed neurapraxia sometimes combined with axonal degeneration in the ulnar nerve at the elbow, compatible with compression at that site. The most sensitive parameters of abnormality in the symptomatic subjects were segmental slowing of motor nerve conduction velocity across the elbow (P less than 0.001) and the amplitude of the compound muscle action potential obtained on stimulating the nerve above the elbow (P less than 0.001). In the 18 asymptomatic diamond assorters, electrophysiological studies revealed an ulnar neuropathy in two (again in the hand used for holding the eye-glass). Ulnar mononeuropathy at the elbow thus seems to be an occupational hazard for diamond assorters and it is worthwhile to elicit occupational history from patients presenting with an ulnar mononeuropathy, especially in Bombay and Gujarat where diamond industry is concentrated.

Simplified technique for recording human cortical & spinal evoked muscle potentials.

Muscle responses evoked on transcranial stimulation of the motor cortex (corticomotor) and motor roots (spinal) were studied in 20 healthy volunteers using a simplification of Rossini's technique and conventional EMG equipment. Cortical motor responses were consistently obtained from the contralateral upper limb with tolerable stimuli. Lower limb motor responses were inconsistent and sometimes required uncomfortably high stimulus strengths. In the upper limbs, peripheral conduction time (PCT) was estimated by the latency of the response to spinal stimulation. A comparable measure of PCT was obtained for the abductor pollicis brevis (APB) from the F-responses. The difference between the latency of the corticomotor response and the PCT was considered to represent central motor conduction time (CMCT). Corticomotor latencies were: APB 18.51 +/- 1.1 msec, biceps 9.77 +/- 0.46 msec and tibialis anterior 26.5 +/- 2.9 msec. CMCT from cortex to C8/T1 segments (APB) was 4.68 +/- 0.6 msec and between cortex and C5/C6 (biceps) 4.24 +/- 0.42 msec.