[A case of lead neuropathy--importance of subclinical entrapment of nerves in lead neuropathy].

The patient was a left handed 25-year-old man who had worked in a vinyl chloride resin factory since July 1987 using lead stearate as a stabilizer. During the two years preceding hospitalization, he had been admitted three times for colicky abdominal pain with constipation and nausea. Anemia and proteinuria without causative diseases were pointed out. Because of progressive muscle weakness of hands which began since January 1989, he was admitted to our neurologic clinic on October 2 1989. Neurological examination showed severe atrophy of both small hand muscles without sensory disturbances. Left hand was predominantly affected, especially in interossei muscles. Laboratory findings are as follows; RBC 3.25 million/cu.mm: Hb 9.7 g/dl:blood lead concentration 100 micrograms/dl: urinary coproporphyrin 4503 micrograms/l: urinary delta-ALA 138 mg/l: and urinary lead excretion after 1 g CaEDTA infusion: 3938 micrograms/day. Electromyography of extensor carpi radialis, flexor carpi ulnaris and opponens showed increased polyphasic, long duration MUPs. Electromyography of dorsal interossei showed fibrillation. Nerve conduction study showed mildly decreased motor and sensory conduction velocities and markedly reduced amplitude of compound muscle action potentials (CAMPs). Investigation by inching method revealed conduction block of left ulnar nerve across elbow. After CaEDTA chelating therapy, 1 g once a week, steady improvement of muscular weakness was observed within a few months. Serial nerve condition studies revealed constant recovery of nerve conduction velocities, amplitude of CMAPs and diminution of conduction block across the left elbow. Conduction block across left elbow without sensory disturbances implies that subclinical cubital tunnel syndrome might have existed in this patients.(ABSTRACT TRUNCATED AT 250 WORDS)