Recovery of glymphatic system function in patients with temporal lobe epilepsy after surgery.

OBJECTIVES: To investigate the recovery of human glymphatic system (GS) function in patients with temporal lobe epilepsy (TLE) after successful anterior temporal lobectomy (ATL) using diffusion tensor image analysis along the perivascular space (DTI-ALPS).

METHODS: We retrospectively analysed DTI-ALPS index in 13 patients with unilateral TLE before and after ATL, and compared the index with 20 healthy controls (HCs). Two-sample t tests and paired t tests were performed to analyse differences in the DTI-ALPS index between patients and HCs. The Pearson correlation analysis was used to observe the relationship between the disease duration and GS function.

RESULTS: The DTI-ALPS index before ATL was significantly lower in the hemisphere ipsilateral to the epileptogenic foci than in the contralateral hemisphere of the patients (p < 0.001, t =  - 4.81) and in the ipsilateral hemisphere of the HCs (p = 0.007, t =  - 2.90). A significant increase in the DTI-ALPS index was found in the hemisphere ipsilateral to the epileptogenic foci after successful ATL (p = 0.01, t =  - 3.01). In addition, the DTI-ALPS index of the lesion side before ATL was significantly correlated with disease duration (p = 0.04, r =  - 0.59).

CONCLUSIONS: DTI-ALPS may be used as a quantitative biomarker evaluating surgical outcomes and TLE disease duration. DTI-ALPS index may also help localise epileptogenic foci in unilateral TLE. Overall, our study suggests that GS may potentially serve as a new method for the management of TLE and a new direction for investigating the mechanism of epilepsy.

KEY POINTS: • DTI-ALPS index may contribute to epileptogenic foci lateralisation in TLE. • DTI-ALPS index is a potential quantitative feature evaluating surgical outcomes and TLE disease duration. • The GS provides a new perspective for the study of TLE.