Direct electrical stimulation (DES) is sometimes used in epilepsy surgery to identify areas that may result in language deficits if resected. Extraoperative language mapping is usually performed using electrocorticography (ECOG) - grids and strip electrodes; however, given the better safety profile of stereoelectroencephalogaphy (SEEG), it would be desirable to determine if mapping using SEEG is also effective. We report a case series of fifteen patients that underwent language mapping with either ECOG (5), SEEG (9), or both (1). Six patients in the SEEG group underwent resection or ablation with only mapping via SEEG. No patients in the SEEG group that underwent resective or ablative surgery experienced persistent language deficits. These results suggest that language mapping with SEEG may be considered as a clinically useful alternative to language mapping with ECOG.

Objective: Resection of colloid cysts, a rare third ventricle pathology, is accepted clinical practice. Owing to their location proximal to deep gray nuclei and forniceal columns, colloid cysts have been theorized to contribute to cognitive decline. Comprehensive pre- and post-operative cognitive testing, however, has rarely been implemented. Methods: We analyzed formal neuropsychological testing performed in 20 patients undergoing endoscopic cyst resection. Pre- and post-operative performance was compared either for each individual patient or according to aggregated neuropsychological factor scores grouped via expert census. A change in performance was deemed significant if (i) it reached statistical significance and (ii) was greater than 1.5 pre-operative standard deviations. Results: Twenty patients with colloid cysts (average diameter 13.3 ± 1.3 mm) underwent matched pre- and post-operative testing. No patient had a significant change in cognitive performance. Neurocognitive metrics assessing cognitive functions typically subsumed by the temporal (p = 0.35), extratemporal (p = 0.20), occipitoparietal (p = 0.31), or frontal lobes (p = 0.11) did not change post-operatively. Similarly, no differences emerged when factor scores were generated according to composite scores of different neurocognitive domains: attention (p = 0.32), executive function (p = 0.14), language (p = 0.98), and visuospatial function (p = 0.42). Conclusions: Neuropsychological testing allows for the careful monitoring of cognitive status before and after surgery and for the identification of patients who may benefit from pre- and post-operative cognitive rehabilitation. It should also be used as a valuable surgical psychometric marker and adjuvant. No significant cognitive decline was observed in this cohort.