Intracranial Investigation of Piriform Cortex Epilepsy During Odor Presentation

Abstract

The piriform cortex is part of the olfactory system, principally receiving input from the lateral olfactory tract and projecting to downstream components of the olfactory network, including the amygdala. Based on preclinical studies, the piriform cortex is vulnerable to injury and can be easily kindled as an onset site for seizures. While the role of the piriform cortex in human epilepsy has been studied indirectly and the subject of speculation, cases of demonstrated piriform cortex seizure onset from direct intracranial recording are rare. We present a pediatric patient with drug-resistant focal reflex epilepsy and right mesial temporal sclerosis with habitual seizures triggered by coconut aroma. The patient underwent stereoelectroencephalography with implantation of olfactory cortices including the piriform cortex. We examined the field potential effects of odorant presentation, the location of seizure onset and ability to recapitulate habitual seizures from olfactory cortices. Surgical workup resulted in resection of the patient’s right amygdala, piriform cortex, and mesial temporal pole, following which she has been seizure free for 20 months without functional decline in cognition or smell.