The pathogenesis of olivary changes in clioquinol intoxication

Inferior olivary changes were found in the central nervous system of five patients with subacute myelo‐opticneuropathy induced by long‐term clioquinol administration. The histological findings in the olivary nuclei could not be distinguished from those seen in olivary hypertrophy due to other causes. In two of the five cases, dentate neurons were relatively well preserved. However, there were minor abnormalities in the neuropil of the dentate nuclei and amiculum olivae with loss of myelin and fibrous gliosis. These changes suggested that processes and efferent fibers of the dentato‐olivary system were degenerating and led to speculation that the olivary changes in clioquinol intoxication might be secondary to distal dominant axonopathy in the dentato‐olivary pathway.