Phenobarbital withdrawal seizures may occur over several weeks before remitting: Human data and hypothetical mechanism

Abstract

This case is the first report of a patient who had phenobarbital (PB) withdrawal seizures after having been seizure-free for 3 years following temporal lobe surgery. The patient had been taking PB for 14 years when a gradual taper of PB was started. When PB was at 60 mg/d, a titration of lamotrigine (LTG) was started. However, typical complex seizures occurred when the patient was on PB 60 mg/d, along with LTG 25 mg/d. PB was increased back to 90 mg/d and levetiracetam (LEV) was titrated. Seizures appeared when the patient was on PB 30 mg/d and LEV 750 mg BID and continued for 3 weeks after PB was stopped and the patient was on LEV 1000 mg BID. For the following 6 months, her aura frequency remained elevated in comparison to her baseline aura of two auras per month for the previous year before the start of the PB taper. She was followed for 24 months after her last PB withdrawal seizure. During the last 8 months, her aura frequency returned to her baseline. As suggested by animal studies, the PB withdrawal seizures and increase in aura frequency in this patient may be explained by changes in her levels of GABA A receptor subunits.