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Background and purpose: We aimed to evaluate (i) glymphatic system function in patients with focal epilepsy in comparison with healthy controls, and (ii) the association between anti‐seizure medication (ASM) response and glymphatic system function by using diffusion tensor image analysis along the perivascular space (DTI‐ALPS). Methods: We retrospectively enrolled 100 patients with focal epilepsy who had normal brain magnetic resonance imaging (MRI) findings, and classified them as "poor" or "good" ASM responders according to their seizure control at the time of brain MRI. We also included 79 age‐ and sex‐matched healthy controls. All patients and healthy controls underwent conventional brain MRI and diffusion tensor imaging. The DTI‐ALPS index was calculated using the DSI studio program. Results: Of the 100 patients with focal epilepsy, 38 and 62 were poor and good ASM responders, respectively. The DTI‐ALPS index differed significantly between patients with focal epilepsy and healthy controls and was significantly lower in patients with focal epilepsy (1.55 vs. 1.70; p < 0.001). The DTI‐ALPS index also differed significantly according to ASM response and was lower in poor ASM responders (1.48 vs. 1.59; p = 0.047). Furthermore, the DTI‐ALPS index was negatively correlated with age (r = −0.234, p = 0.019) and duration of epilepsy (r = −0.240, p = 0.016) in patients with focal epilepsy. Conclusion: Our study is the first to identify, in focal epilepsy patients, a greater reduction in glymphatic system function among poor ASM responders compared to good responders. To confirm our results, further prospective multicenter studies with large sample sizes are needed. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to investigate alterations of the glymphatic system function in patients with cluster headache. Methods: We enrolled patients with cluster headache and healthy controls, and they underwent brain magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI). We used the MRIcron and DSI studio programs for DTI preprocessing and DTI analysis with perivascular space (DTI‐ALPS) index calculation. Results: Fourteen patients with cluster headache and 23 healthy controls were enrolled. The DTI‐ALPS indexes of the groups were significantly different. The DTI‐ALPS index for the patients with cluster headache was lower than that for the healthy controls (1.586 vs. 1.786, p = 0.044). There was a significant negative correlation between the DTI‐ALPS index and age in the patients with cluster headache (r = −0.549, p = 0.042). However, the DTI‐ALPS index was not associated with other clinical characteristics, including disease duration and headache intensity (r = −0.405, p = 0.150; r = −0.048, p = 0.869, respectively). Conclusion: Patients with cluster headache had a lower DTI‐ALPS index than the healthy controls; this might indicate glymphatic system dysfunction in the patients with cluster headache. Further research is required to determine whether glymphatic system dysfunction is related to the pathophysiology of cluster headache. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to analyze the glymphatic system function and its relationship with clinical characteristics, global diffusion tensor imaging (DTI) parameters, and global structural connectivity in treatment‐naïve patients with newly diagnosed focal epilepsy. Methods: This retrospective single‐center study investigated patients with focal epilepsy and healthy controls. All participants underwent routine brain magnetic resonance imaging and DTI. DTI analysis along the perivascular space (DTI‐ALPS) was used to evaluate glymphatic system function. We also calculated the measures of global DTI parameters, including whole‐brain fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), and performed a graph theoretical network analysis to measure global structural connectivity. Results: A total of 109 patients with focal epilepsy and 88 healthy controls were analyzed. There were no significant differences in the DTI‐ALPS index (1.67 vs. 1.68, p = 0.861) between the groups. However, statistically significant associations were found between the DTI‐ALPS index and age (r = ‐0.242, p = 0.01), FA (r = 0.257, p = 0.007), MD (r = −0.469, p < 0.001), AD (r = −0.303, p = 0.001), RD (r = −0.434, p < 0.001), and the assortative coefficient (r = 0.230, p = 0.016) in patients with focal epilepsy. Conclusion: The main finding of this study is that DTI‐ALPS index is significantly correlated with global DTI parameters and structural connectivity measures of the brain in patients with focal epilepsy. In addition, DTI‐ALPS index decreases with age in these patients. We conclude that the DTI‐ALPS index can be used to investigate glymphatic system function in patients with focal epilepsy. [ABSTRACT FROM AUTHOR]