Abstracts

Rationale: Encephaloceles are protrusions of brain parenchyma through osseous defects and are rare but known causes of drug resistant epilepsy (DRE). Temporal lobe encephaloceles (TEs) are increasingly identified in this group due to increase in knowledge and advances in neuroimaging .¹ Additionally, encephaloceles have been associated with increased intracranial hypertension (IIH) in individuals with increased body mass index (BMI).² Select patients become seizure-free with lesionectomy.³ We re-reviewed the MRI images in DRE patients at our center with previously reported normal MR-imaging to evaluate for encephaloceles._x000D_
Methods: We retrospectively reviewed patients at University of Maryland Epilepsy Center between January 1, 2017- April 30, 2022 with DRE and normal (non-lesional) MR imaging. A board-certified neuroradiologist re-evaluated the MRIs in this cohort of patients for presence of encephaloceles. Additionally, demographic, clinical, electrophysiologic, and neuropsychological information were also obtained.

Results: There were a total of 23 patients identified with a diagnosis of DRE and normal imaging at our center. Mean age was 43 (range 21-82) and 13 (56%) patients were females. Upon re-review of MRI, new encephaloceles were identified in six (26%) patients: five unitemporal (left) and one bitemporal. Clinically, five of these patients were female with an average BMI of 37 (21-55). Three (50%) of these patients had a diagnosis of IIH. Three (50%) patients had seizure-onset zones that were concordant with newly identified encephaloceles. Radiologically, two (33%) had a 1.5 Tesla MRI and four (66%) had a 3 Tesla MRI. Thin cuts through the temporal lobes and coronal images were used in all patients. Two (33%) patients had concordant FDG-PET studies._x000D_ _x000D_ Conclusions: At our center, six (26%) patients with DRE and normal MR imaging were identified to have a temporal encephalocele on re-review of imaging.  Encephaloceles should be actively searched for in patients with DRE. Factors that may aid in identifying previously unreported cases include increased knowledge and awareness with attention to clinical factors such as BMI. This study also reiterates the importance of early identification of the encephaloceles as they may be amenable to successful surgical treatment.

References:_x000D_ 1. Panov F, et al. Epilepsy with temporal encephalocele: Characteristics of electrocorticography and surgical outcome. Epilepsia. 2016 Feb;57(2):e33-8Epub 2015 Dec 19._x000D_ 2. Tse GT, et al. Anterior temporal encephaloceles: Elusive, important, and rewarding to treat. Epilepsia. 2020;61(12):2675. Epub 2020 Oct 23. _x000D_ 3. Sandhu MRS, et al.  Management of patients with medically intractable epilepsy and anterior temporal lobe encephaloceles. J Neurosurg. 2021 Sep 10;136(3):709-716. doi: 10.3171/2021.3.JNS21133_x000D_  _x000D_ Funding: None