Vincristine-induced subclinical peroneal neuropathy with bilateral ptosis

Abstract

Toxic vincristine-induced polyneuropathy is a common complication of treatment by this antineoplastic drug. Peripheral nerves in the extremities are often affected, but lesions of other nerves are also possible. Especially severe toxic damage occurs in children with hereditary motor sensory neuropathy. In this paper, we describe a boy aged 5 years suffering from medulloblastoma, with complete initial neurosurgical removal of the tumor, who had no cranial innervation failure or clinical signs of polyneuropathy before the introduction of vincristine therapy. Family history was negative for hereditary neuropathy. During initial radio-chemotherapy treatment, he received a total of six individual doses of vincristine. After the sixth treatment, he developed ptosis on the right eye and in a few days also on the left eye, with otherwise normal ophthalmic status, no other cranial nerve failure of signs of neuropathy, and no other toxic effects of treatment except for intermittent leukopenia, and no radiologic signs of progression on magnetic resonance imaging. The nerve conduction study showed reduced amplitude of both peroneal nerves, normal in others. We concluded that clear clinical cranial neuropathy must have developed as the result of vincristine neurotoxicity despite the findings of subclinical peroneal axonal peripheral neuropathy.