Histopathological Findings in Brain Tissue Obtained during Epilepsy Surgery

TLDR

Detailed neuropathological information on structural brain lesions underlying seizures is essential for understanding drug‑resistant focal epilepsy, and this study reports diagnoses from 9,523 patients who underwent epilepsy surgery across 36 centers in 12 European countries over 25 years. The authors aimed to characterize the histopathological diagnoses obtained from resected brain specimens in this large cohort. Histopathological diagnoses were established by examining resected specimens either locally (41 %) or at the German Neuropathology Reference Center for Epilepsy Surgery (59 %). Among the patients, the mean epilepsy duration before surgery was 20.1 years in adults and 5.3 years in children, 71.9 % of operations involved the temporal lobe, and 36 distinct diagnoses across seven categories were identified, with hippocampal sclerosis (36.4 %, mainly adults), tumors (23.6 %, mainly ganglioglioma), and malformations of cortical development (19.8 %, mainly focal cortical dysplasia in children) being most common, while 7.7 % remained undiagnosed. Funding was provided by the European Union and other sources.

Abstract

Detailed neuropathological information on the structural brain lesions underlying seizures is valuable for understanding drug-resistant focal epilepsy.We report the diagnoses made on the basis of resected brain specimens from 9523 patients who underwent epilepsy surgery for drug-resistant seizures in 36 centers from 12 European countries over 25 years. Histopathological diagnoses were determined through examination of the specimens in local hospitals (41%) or at the German Neuropathology Reference Center for Epilepsy Surgery (59%).The onset of seizures occurred before 18 years of age in 75.9% of patients overall, and 72.5% of the patients underwent surgery as adults. The mean duration of epilepsy before surgical resection was 20.1 years among adults and 5.3 years among children. The temporal lobe was involved in 71.9% of operations. There were 36 histopathological diagnoses in seven major disease categories. The most common categories were hippocampal sclerosis, found in 36.4% of the patients (88.7% of cases were in adults), tumors (mainly ganglioglioma) in 23.6%, and malformations of cortical development in 19.8% (focal cortical dysplasia was the most common type, 52.7% of cases of which were in children). No histopathological diagnosis could be established for 7.7% of the patients.In patients with drug-resistant focal epilepsy requiring surgery, hippocampal sclerosis was the most common histopathological diagnosis among adults, and focal cortical dysplasia was the most common diagnosis among children. Tumors were the second most common lesion in both groups. (Funded by the European Union and others.).