Surgical strategy for temporal lobe epilepsy with dual pathology and incomplete evidence from EEG and neuroimaging

Coexistence of hippocampal sclerosis (HS) and a temporal neocortical lesion, including focal cortical dysplasia, vascular malformations or benign primary brain tumors, is defined as dual pathology. In the majority of cases, the complete evidence based on electroencephalogram (EEG) and magnetic resonance imaging (MRI) for each of the dual pathological lesions is difficult to obtain. As a result, patients with dual pathology are poor surgical candidates due to potential incomplete resection of the epileptogenic zone. The current study retrospectively reviewed 24 patients with potential dual pathology and incomplete EEG and MRI evidence, aiming to provide novel surgical strategies. The results revealed a significantly worse seizure-free outcome for patients with incomplete EEG and MRI data compared with patients who received a clear diagnosis of dual pathology based on complete test results (11.1 vs. 60.0%; P<0.05). Notably, satisfying surgical (seizure-free) outcomes were still achieved in 60% of patients with unclear EEGs to locate the onset zone and clear MRI scans identifying the sclerotic hippocampus and nearby neocortical lesions, which could be resected together. In patients with multiple epileptogenic onsets or with widespread epileptic discharges, the hippocampus should be spared from resection due to concern for potential postsurgical mood or memory disorders. In conclusion, patients with resection of the sclerotic hippocampus and neocortical lesion had improved seizure-free outcomes compared with patients who received individual lesion resection. The current study aimed to provide a novel surgical strategy for neurosurgeons treating epileptic patients with dual pathology.