A case of transient gait disturbance due to elevated serum concentration of perampanel at the time of infection

Perampanel (PER) is a selective, non-competitive alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist used in the treatment of pediatric epilepsy. We report a case of transient gait disturbance associated with significantly increased serum PER concentration during an infection. A 10-year-old girl with focal epilepsy caused by ulegyria was undergoing treatment with PER, levetiracetam, and lacosamide. She was introduced to our hospital with a sudden onset of gait disturbance. Laboratory findings revealed elevated levels of serum C-reactive protein and PER. Based on these findings, we suspected that the symptoms were caused by PER. The symptoms resolved rapidly and inflammatory markers and the PER concentration eventually returned to normal levels. Infection-related suppression of CYP3A4 activity has been previously suggested to increase serum PER concentration. Patients with epilepsy with structural etiologies may be more susceptible to neurological symptoms triggered by elevated PER levels, particularly during infections. Further research is necessary to elucidate the underlying mechanisms of this phenomenon and explore the role of inflammation in altered pharmacokinetics of antiseizure medications.