OBJECTIVE: Hippocampal sclerosis (HS) is the most common histopathological abnormality in adults with drug-resistant mesial temporal lobe epilepsy (MTLE) who are candidates for surgery. In 2013, the International League Against Epilepsy (ILAE) Task Force subdivided HS into three types: HS-ILAE type 1 (severe neuronal loss and gliosis predominantly in CA1 and CA4), HS-ILAE type 2 (CA1-predominant), and HS-ILAE type 3 (CA4-predominant). The aim of this study was to assess the association between HS-ILAE types and cognitive profiles of MTLE-HS patients. METHODS: A total of 302 patients were retrospectively included, comprised of 253 MTLE-HS patients with a postoperative ILAE classification of HS as follows: 194 HS-ILAE type 1, 57 HS-ILAE type 2, and two HS-ILAE type 3; and 49 MTLE patients without HS. Demographic variables, clinical characteristics, postoperative outcome, and cognitive performance were compared between patients with HS-ILAE type 1, with HS-ILAE type 2, and without HS, who served as internal controls. Height cognitive domains were examined: general cognition, verbal and nonverbal episodic memory, language, executive functions, short-term and working memory, perceptual-motor speed, and visuoconstructive abilities. RESULTS: The pattern of hippocampal neuronal loss was not associated with age at epilepsy onset, the presence of specific initial precipitating events, other clinical characteristics, or postoperative outcome. Patients with HS-ILAE type 1 demonstrated significantly poorer performance in visuoconstructive and language tasks compared with those with HS-ILAE type 2 or patients without HS. No significant differences were observed between groups in verbal and nonverbal episodic memory, short-term memory, executive functions, or perceptual-motor speed. SIGNIFICANCE: HS-ILAE subtype has a modest yet differential impact on patient performance, with HS-ILAE type 1 patients demonstrating overall poorer outcomes across two cognitive domains: language and visuoconstructive function. These findings suggest that cognitive impairment in MTLE-HS likely reflects a complex interplay among multiple pathological processes, including, in part, neuronal loss within specific hippocampal subfields. More targeted neuropsychological assessments focusing on the functional integrity of distinct hippocampal subregions are warranted.
Thanh et al. (2026) studied this question.