Pseudotumour cerebri due to phenytoin in a child.

Pseudotumour cerebri is a manifestation of intracranial hypertension in an otherwise normal individual. We hereby report phenytoin-induced pseudotumour cerebri in a 9-year-old boy who received phenytoin as a prophylactic anticonvulsant following surgical removal of unifocal Langerhans cell histiocytosis involving the right frontal bone. The child was evaluated for headache and diplopia after starting phenytoin and on evaluation was found to have bilateral sixth nerve palsy. The only abnormality detected was an elevated cerebrospinal fluid pressure. Withdrawal of phenytoin resulted in complete resolution of symptoms. Despite meticulous literature search, we found only 1 other report of phenytoin induced pseudotumour cerebri. We report this case to highlight the need to consider this entity whenever a patient presents with new onset or persistent headache and visual symptoms soon after starting a medication since a high degree of suspicion is needed to arrive at the diagnosis and to take appropriate steps before it progresses to harmful complications such as vision loss.