Toxic polyneuropathy due to methyl n-butyl ketone. An industrial outbreak.

Cases of toxic distal polyneuropathy have been studied in a plant producing plastic-coated and color-printed fabrics. After the screenig of 1,157 employees, a total of 86 verified cases were detected. Of these, 11 were moderate to severe in intensity and usually with motor and sensory involvement; 38 were mild, with sensory signs prevailing; and 37 were minimal, but with characteristic electro-diagnostic abnormalities. Muscle weakness and electromyographic abnormalities were predominantly distal. Reflex loss was minimal. Sensory deficits were distal and limited to pain, touch, and temperature discrimination with occasional loss of vibration sense. The distribution of involvement severity of the disorder, and temporal course of the outbreak correlated with exposure with methyl n-butyl ketone. After elimination of this agent improvement was noted in the majority of cases.