Irreversible Cerebellar Atrophy as a Complication of Short-Term Phenytoin Exposure: Clinical Improvement Following Discontinuation of the Culprit

Abstract

Phenytoin (diphenylhydantoin) is a widely used antiepileptic drug for controlling both generalized and partial seizures. Reversible cerebellar symptoms, including cerebellar ataxia, have been recognized as an adverse event of phenytoin use for many years. On the other hand, cerebellar degeneration has been reported with chronic use in an epileptic patient treated with this drug. We are reporting an interesting case of phenytoin induced acute pan-cerebellar syndrome with cerebellar atrophy on neuro-imaging that improved many years after discontinuation of the drug. Discontinuation of phenytoin may give a chance for the patient to recover slowly, months after stopping the drug. It is very important for the attending neurologist to educate the patients and their families on some common clinical manifestations suggestive of drug toxicity and perform a regular follow-up and clinical examination at regular intervals.

Relato de caso: Atrofia cerebelar associada à intoxicação por Fenitoína em um munícipio da região amazônica

“…Estudos prévios afirmaram também que os efeitos tóxicos da Fenitoína por via oral causam danos cerebelares e ao sistema vestibular por dose-dependente (Algahtani et al, 2020;Calsani, 2007). As doses elevadas deste anticonvulsivantes associadas ao tratamento crônico foram associadas a atrofias marcantes do cerebelo, como alterações comportamentais, aumento de frequência de crises convulsivas, hirsutismo, hiperplasia gengival, dentre outros efeitos referidos ao sistema nervoso central (Calsani, 2007;Iorga & Horowitz, 2022).…”

Incidence and Characteristics of Cerebellar Atrophy/Volume Loss in Children with Confirmed Diagnosis of Tuberous Sclerosis Complex

“…Several studies have demonstrated the correlation between cerebellar atrophy and phenytoin toxicity in patients with epilepsy [ 20 , 21 ]. Phenytoin was a widely used anti-seizure drug for controlling both generalized and partial seizures.…”

Cerebellar atrophy and ataxia caused by "White Pill" (phenytoin) poisoning: A case report

“…Phenytoin is the oldest non-sedating drug used in the treatment of epilepsy. It is primarily used for the treatment of tonic-clonic and partial seizures [4]. Phenytoin has a highly selective inhibitory effect on the motor area of the cerebral cortex.…”

“…Cerebellar atrophy, demonstrated radiologically or histologically, was common in patients who had been treated with phenytoin for a year or more [4,8], whether or not they had symptoms or clinical signs of cerebellar disturbance. Phenytoin can cause permanent cerebellar damage.…”