Reversible forms of motor neuron disease. Lead "neuritis".

A 50-year-old battery worker had clinical signs of motor neuron disease: weakness, wasting, and active reflexes. Nerve conduction velocities, electromyogram, and motor unit territory indicated that the disorder was neuronal. Biochemical abnormalities were characteristic of lead intoxication, and the clinical disorder was reversed after treatment with penicillamine. This case and others suggest that "lead neuritis" is a form of motor neuron disease, rather than a neuropathy. Except for those persons who have clearly been exposed to lead, it is doubtful that lead intoxication is responsible for more than a small number of patients with amyotrophic lateral sclerosis (ALS). Considering the prognostic implications, however, prior to making the diagnosis of ALS, lead intoxication should be considered.