Impaired Olfactory Function in Patients with Mesial Temporal Lobe Epilepsy Associated with Hippocampal Sclerosis

Objectives: It has been proposed that olfactory function disorders, such as parosmia or hyposmia, were associated with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). In this study, we aimed to compare the olfactory function and its subtypes between MTLE-HS and healthy controls. Methods: We recruited 22 non-operated consecutive patients diagnosed with MTLE-HS and 22 aged and gender-matched healthy controls (HC). After a detailed clinical evaluation, we used a standardized tool, Sniffin' Sticks test, to evaluate the olfactory function. Results: The mean age was 37.5 (+/- 12.7) years in the MTLE-HS group and 36.9 (+/- 10.3) years in the HC group. There were 14 females and eight males in both groups. Threshold, discrimination, identification and TDI scores were analyzed separately for each group. The threshold and discrimination values were similar in MTLE-HS and HC groups (p=0.063). Identification and TDI scores were significantly lower in the MTLE-HS group, respectively p<0.01 and p<0.001. Conclusion: We have demonstrated the impaired olfactory function in MTLE-HS patients in the Turkish population. For the MTLE-HS patients, both peripheral changes, as well as structural or functional alterations in mesial temporal lobes and prefrontal lobes, have been proposed, and our results are in favor of central involvement.