Alterations of Glymphatic System Before and After Shunt Surgery in Patients With Idiopathic Normal Pressure Hydrocephalus: A Longitudinal Study.

AIMS: This study aimed to assess the glymphatic dysfunction in idiopathic normal pressure hydrocephalus (iNPH) patients and its recovery post-shunt surgery using diffusion tensor image analysis along perivascular spaces (DTI-ALPS).

METHODS

Thirty-five iNPH patients and forty healthy controls (HC) underwent MRI scans and neuropsychological assessments at baseline. A follow-up study, conducted three months post-shunt surgery, included fifteen iNPH patients. The DTI-ALPS index was calculated to assess the glymphatic system status. Group differences were evaluated using the Mann-Whitney U test, while the paired Wilcoxon signed-rank test was employed to compare pre-operative and post-operative ALPS indices. Multiple linear regression was utilized to analyze the association between changes in the ALPS index (ΔALPS) and alterations in clinical scores.

RESULTS

Baseline examinations disclosed iNPH patients had a lower ALPS index than HC (p < 0.0001). We found a significantly increased ALPS index at 3 months after surgery compared to baseline (p < 0.0001). Positive correlations between theΔALPS and the increments of MMSE score (ΔMMSE) were found in all iNPH patients. Baseline age and ΔALPS emerged as significant predictors of ΔMMSE, with the model explaining 68.13% of the variance (R2 = 0.6813).

CONCLUSION

Glymphatic function in iNPH was enhanced following shunt surgery, which positively impacted cognitive recovery. The DTI-ALPS index may serve as a useful predictor of shunting efficacy in iNPH patients.