SMON as seen from Bombay.

Clioquinol is still consumed in India in considerable amounts but no new case reports have appeared since 1977. A review is made for a regional neurotoxicology group of an enquiry that we conducted in Bombay to gather information regarding SMON, spanning the period of 1967 to 1976. Nine patients were diagnosed with a variable degree of confidence as suffering from SMON, two from a retrospective search and seven after a prospective watch for the disease. Myelopathy with predominant more distal dysesthesia was seen more often than the full-blown picture of SMON. The peripheral neuropathy component (N) diagnosed clinically or electrophysiologically was seen only once. Pyramidal tract disturbances and resulting spasticity was as striking as posterior column disorder and sensory ataxia. Subacute myelopathy was seen in six patients, optico-myelopathy in two, and myeloneuropathy only once. It was clear that clioquinol has potential neurotoxicity, but no definitive explanation was forthcoming about the vast difference in the prevalence of SMON as reported from Japan and seen by us in Bombay.