Vincristine-induced polyneuropathy in a child with stage I Wilms’ tumour presenting with unilateral abducens nerve palsy

A 4-year-old boy presented with right esotropia while receiving vincristine and dactinomycin for stage I Wilms’ tumour according to the National Wilms Tumour Study-5 protocol. On examination, he had isolated limitation of his right lateral gaze. CT of the brain and cerebrospinal fluid examination were normal. A nerve conduction velocity study which was performed on the peripheral nerves revealed predominant motor polyneuropathy compatible with axonal loss involving the upper limbs. The patient had received a cumulative vincristine dose of 17 mg/m 2 before developing esotropia. Vincristine-induced abducens nerve mononeuropathy and subclinical motor polyneuropathy was suspected. Unilateral esotropia markedly improved after the discontinuation of vincristine and a short course of oral pyridoxine treatment.