Authors :
Presenting Author: Jian Xu, MD PhD – Henry Ford Health
Jules Constantino, MD, FRACP – Henry Ford Health
Ellen Air, MD PhD – Henry Ford Health
Gregory Barkley, MD – Henry Ford Health
Daniel Noujaim, MD – Henry Ford Health
Vibhangini Wasade, MD – Henry Ford Health
Rationale:
Temporal lobe encephaloceles (TEs) are recognized as epileptogenic and usually surgically treatable in cases of drug-resistant, unilateral temporal lobe epilepsy. However, in patients with epilepsy associated with bilateral temporal encephaloceles (BTEs), treatment strategies are less clearly established. Here, we present two cases of BTEs evaluated with stereo-electroencephalography (sEEG), which revealed epileptogenic zones localized to the mesial temporal regions, distinct from the encephaloceles themselves.
Methods:
We report two adult female patients with obesity and drug-resistant epilepsy (DRE) associated with BTEs. Both underwent comprehensive presurgical evaluation, including prolonged scalp video-EEG monitoring in the epilepsy monitoring unit (EMU), and sEEG.
Patient 1 was a 38-year-old Caucasian woman with a 20-year history of DRE. Brain MRI demonstrated features consistent with BTEs and signs of idiopathic intracranial hypertension (IIH), although lumbar puncture revealed normal opening pressure. PET imaging showed right temporal hypometabolism. Scalp EEG revealed predominantly right frontotemporal and bifrontotemporal ictal patterns, with interictal discharges localized to the right temporal lobe. sEEG implantation targeted bilateral temporal and frontal regions.
Patient 2 was a 44-year-old African-American woman with a history of childhood self-limited epilepsy and a 4-year history of DRE. MRI showed bilateral inferior temporal encephaloceles, and CT imaging identified arachnoid pits in the middle cranial fossa. Lumbar puncture showed normal opening pressure. PET scan revealed bitemporal hypometabolism, more pronounced on the right. Scalp EEG demonstrated independent interictal discharges from both temporal lobes and independent ictal onsets in right and left temporal regions. sEEG was performed with electrodes placed in bilateral temporal lobes, including the encephaloceles, and frontal regions.
Results:
sEEG monitoring in both patients confirmed bitemporal seizure onsets. In Patient 1, four focal impaired consciousness seizures were recorded, with sEEG onsets preceding clinical symptoms by up to 7 seconds. Two seizures originated from right hippocampal contacts and two from left hippocampal contacts. In Patient 2, five focal impaired consciousness seizures were captured, with three originating from right and two from left hippocampal contacts. sEEG onsets preceded clinical manifestations by 12 to 50 seconds, with ictal activity consistently appearing over hippocampal contacts at least 6 seconds before involvement of the respective encephalocele contacts. Both patients subsequently underwent implantation of a Responsive Neurostimulation (RNS) system with depth leads targeting bilateral mesial temporal regions.
Conclusions:
Bitemporal encephaloceles, although rare, can be found in cases of intractable bitemporal epilepsy. Our data suggests that the structural abnormalities of BTEs do not necessarily correspond to the epileptogenic zone and can coexist with bilateral mesial temporal epilepsy.
Funding: None.