Mercury intoxication simulating amyotrophic lateral sclerosis.

A 54-year-old man had a syndrome resembling amyotrophic lateral sclerosis after a brief but intense exposure to elemental mercury. The syndrome resolved as his urinary mercury levels fell. Mercury toxicity must be considered not only in individuals with recent anterior horn-cell dysfunction but also with otherwise unexplained peripheral neuropathy, tremor, ataxia, and a gamut of psychiatric symptoms including confusion and depression.