Memory changes in patients with hippocampal sclerosis submitted to surgery to treat mesial temporal lobe epilepsy

This study was performed with the purpose of analysing the relationship between epileptological and surgical variables and post-operative memory performance, following surgery for refractory mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS).

Logical memory (LM) and visual memory (VM) scores for immediate and late follow-up of 201 patients operated for MTLE/HS were reviewed. Scores were standardized with a control group of 54 healthy individuals matched for age and education. The Reliable Change Index (RCI) was calculated to verify individual memory changes for late LM and VM scores. A multiple linear regression analysis was carried out with the RCI, using LM and VM scores as well as the clinical variables.

A total of 112 (56%) patients had right HS. The RCI of the right HS group demonstrated that 6 (7%) patients showed improvement while 5 (6%) patients showed decreased scores in late LM; for late VM, 7 (8%) patients presented improvement, and 2 (3%) patients showed poorer scores. RCI of the left HS group showed that 3 (3%) individuals showed improved scores, while scores of 5 (4%) patients worsened for late LM; for late VM, 3 (3%) patients presented higher scores and 6 (5%) showed lower scores. Left HS and advanced age at onset of the first epileptic seizure were predictors of late LM loss (p<.05).

Left MTLE/HS and seizure onset at advanced ages were predictive factors for the worsening of late LM. We observed poorer baseline LM function in the left HS group and improvement of LM in some patients who had resection of the right MTL. Patients in the right HS group showed a higher percentage of reliable post-operative improvement for both VM and LM scores.