Abstracts

Rationale: Interictal positron emission tomography (PET) using [¹⁸F] flourodeoxyglucose (FDG) is commonly used to identify the epileptogenic zone in patients with drug-resistant partial epilepsy. The development of PET/CT has decreased scan time and improved anatomic localization, with both of these being particularly important in children. Seizures are uncommon during PET scans and different ictal metabolic patterns have been reported in few children. We report on the utility of ictal PET/CT in the management of two patients with recurrent frequent non convulsive seizures. Methods: [¹⁸F] flourodeoxyglucose ictal PET/CT was performed in two children with refractory non convulsive status epilepticus. Continuous scalp EEG monitoring was used during the tracer uptake period to confirm the ictal state and to assist in the interpretation of the FDG uptake. Results: Patient #1: 32 month old with partial seizures since age 1 year presented with deteriorating level of consciousness and recurrent episodes of confusion. MRI was normal. Video EEG revealed right hemispheric almost continuous electrographic seizures. Patient had failed treatment with Midazolam drip, Phenobarbital, Isoflourane anaesthesia and Topiramate. PET/CT was performed with continuous scalp EEG recording. Two diffuse right hemispheric electrographic seizures were recorded 20 minutes and one minute prior to the injection and a third electrographic seizure was captured during the scanning. PET/CT revealed an area of hypermetabolism in the right middle frontal gyrus. The patient underwent invasive monitoring with subdural electrodes which confirmed PET scan results. The patient is seizure free at one year follow up after right frontal resection. Pathological diagnosis was non-balloon cell cortical dysplasia. Patient # 2: 10 year old with tuberous sclerosis complex and recurrent episodes of status epilepticus with minor convulsive features. He had previously failed corpus callosotomy and vagus nerve stimulation. He presented with disturbed sensorium and recurrent episodes of subtle stiffening of the left hand. Video EEG revealed frequent right hemispheric EEG seizures with no clear localization. FDG PET/CT was performed with continuous scalp EEG recording. One electrographic seizure was recorded three minutes prior to the injection and five brief electrographic seizures were recorded during scanning. FDG PET/Ct revealed multiple areas of increased uptake in the right hemisphere in the frontal and parietal regions corresponding to multiple cortical tubers. Seizures resolved with intravenous midazolam drip and intravenous Phenobarbital. Conclusions: PET/CT with continuous EEG monitoring is feasible and can provide valuable information in a selected group of children with frequent focal non convulsive seizures.