Abstracts

Rationale: Encephaloceles, herniation of intracranial contents through a bony defect, is rare, but increasingly identified as a source of medically refractory epilepsy. Temporal lobe encephaloceles (TLE) are commonly overlooked on initial imaging studies despite advancements in imaging modalities, only in retrospect are they recognized as a potential ictal generators. The lack of distinct ictal semiology and variable electroclinical findings associated with TLE should be reported in order to contribute to the understanding and management of these lesions. Our aim is describe these findings in TLE and recognize its potential for false localization on electroencephalogram (EEG). We report 3 such cases, 2 of which underwent surgical management. Methods: Case 1: 44 YO woman with epilepsy for 10 years. Semiology: out of body sensation, tachycardia, dilated pupils, lip smacking, right head version, progressing to generalized tonic-clonic seizure (GTC). Most of the seizures with nocturnal predominance. Case 2: 27 YO man with epilepsy for 12 years. Semiology: déjà vu, dizziness, blurry vision, visual perceptual disturbances, and out of body sensation followed by unresponsiveness and confusion.Case 3: 24 YO man with epilepsy for 8 years. Semiology Type 1: tingling/cramping sensation in left UE followed by unresponsiveness and right head version with subsequent GTC (sign of 4, right arm extended). Type 2: out of body sensation, unresponsiveness, left eye blinking, and swallowing. Results: Case 1 VEEG: Bi-temporal intermittent delta slowing (right>left), sharp waves in left frontal and vertex regions. One seizure from right temporal, 2nd seizure regional left hemispheric maximum anterior, 3rd seizure was non-localizable due to bi-temporal involvement. MRI demonstrated 0.7x0.4 cm encephalocele in the left middle cranial fossa floor and normal hippocampal anatomy. Ictal SPECT showed bilateral temporal lobes hyperperfusion. PET scan showed hypometabolism in the left anterior mesial and inferior temporal lobe. Case 2 VEEG: Right frontotemporal intermittent rhythmic slow, right frontotemporal sharp wave, and occasional left frontotemporal sharp wave. One seizure was recorded from the right frontotemporal region, 2nd seizure lateralized right hemisphere. MRI showed a 9x8 mm right anterior mesial temporal pole encephalocele with gliosis and normal hippocampal anatomy. PET scan showed hypometabolism in the right temporal lobe. Tailored lesionectomy was performed. Outcome: Engel 1 at 12 months follow up. Case 3 VEEG: Left hemispheric intermittent slow and left posterior temporal slow. Seizures were localized to the left temporal region. MRI showed a cystic lesion in the left middle cranial fossa extending into the sphenoid bone measuring 1x1.3 cm and normal hippocampal anatomy. PET showed left temporal lobe hypometabolism. Ictal SPECT was consistent with bilateral anterior temporal hyperperfusion. IOM ECoG showed paroxysmal fast activity in the region of the encephalocele. Tailored lesionectomy was performed at the left temporal pole. Outcome: Engel 1 at 15 months follow up. Conclusions: Temporal lobe encephalocele may be an under-recognized source of medically refractory epilepsy due to the variable electroclinical findings. Literature suggest less than 5% of temporal lobe encephaloceles are associated with epilepsy. Correct identification of these lesions is of significant importance as this may be the etiology of the seizures. As shown in our cases, EEG findings can be misleading. Surgical approach with multiple modalities is required to achieve good surgical outcome. Funding: No funding