Ictal 18F-FDG PET/CT Findings in Clinically Silent Seizures Caused by a Frontoethmoidal Nasal Meningoencephalocele

A 55-year-old man presented with a 5-year history of drug-resistant epilepsy with monthly clinical seizures. Investigation revealed a left frontoethmoidal nasal meningoencephalocele secondary to osseous fibrous dysplasia. Video-EEG failed to capture scalp epileptiform activity, but a concomitant intranasal electrode recorded frequent, clinically silent electrographic seizures. This continuous intranasal EEG recording during the uptake phase of 18 F-FDG PET/CT confirmed eight localized subclinical seizures, each lasting 1–3 minutes. The PET scan demonstrated intense focal hypermetabolism at the herniated tissue tip, matching the electrographic EEG ictal activity. Complete endoscopic endonasal lesionectomy rendered the patient seizure-free for 4 years.