Abstracts

Rationale:
Encephaloceles are protrusions of cerebral parenchyma through skull and meningeal defects that may present as “lesion negative” epilepsy. Oftentimes, they are identified after extensive pre-surgical evaluation or retrospectively. Early recognition of these subtle lesions may prove to be a potentially treatable cause of epilepsy with surgical intervention. Furthermore, the optimal surgical strategy has not been well-established, though prior studies have suggested lesionectomy and temporal lobectomy for extemporal and temporal lobe encephaloceles, respectively. We present a comprehensive review of encephalocele management at our institution by describing the characteristics, role of ancillary testing in the pre-surgical evaluation, and surgical management.
Method:
This retrospective descriptive study reviewed 33 patients with epilepsy and encephaloceles at the Cleveland Clinic between January 2000 and May 2020. Data collection included encephalocele location, characteristics, ancillary testing in the pre-surgical evaluation (EEG, MRI, PET, SPECT, MEG, MRI post processing/VBM), pathological findings, surgical management and post-surgical seizure outcomes.
Results:
Upon review of 123 adult patients with encephaloceles who presented with possible seizure, we found 33 with confirmed epilepsy. The average age was 44 (23-71) and 52% were females. Twenty five of these patients underwent surgical resections, 23 of whom had temporal, one parietal, and one frontal lobe encephaloceles. Eight patients had not undergone surgical intervention. Ancillary testing findings were reviewed in detail with the most revealing modalities illustrated on Table 1. A tailored resection sparing the hippocampus was performed in 87% (20/23) of patients with outcome (Engel I) in 65% (15/23) and at least 7-month follow-up (7-84 months). Three patients underwent temporal lobectomy including mesial structures with favorable outcomes (Engel I) achieved in two patients, with follow-up in 1-31 months. Pathology showed gliosis in 15 with co-existent focal cortical dysplasia type I in 12 out of 15 patients.
Conclusion:
Despite advances in imaging modalities for pre-surgical evaluation, encephaloceles continue to be an under-recognized etiology of refractory epilepsy. When reviewing pre-surgical ancillary testing, we found the most concordance with MRI, and PET scans followed by SPECT. In cases with conflicting results, additional assessment with invasive evaluation may be warranted. This study further expands on the importance of early identification of these lesions as they are amenable to good surgical outcomes and suggests that tailored resection sparing the hippocampus may deem positive post-surgical seizure outcomes.
Funding:
:None