Phenytoin Toxicity Presenting With Ataxia and Nystagmus: A Case Report

Phenytoin has a narrow therapeutic window, and elderly patients with multiple comorbidities are more susceptible to developing toxicity.This report details a patient who developed cerebellar symptoms during admission.Elevated phenytoin levels were identified and were higher still when corrected for low serum albumin.Structural, central infective, and epileptic causes were excluded.Despite repeated dose adjustments, therapeutic levels could not be maintained.Establishing therapeutic levels may have been further complicated by declining renal function and concurrent infection, and phenobarbitone levels were also supratherapeutic.He deteriorated and subsequently died.This case highlights the need for early phenytoin level monitoring when toxicity is suspected, particularly in frail patients with hypoalbuminemia, renal impairment, or acute illness, where dose titration is challenging.