Impaired Glymphatic-Meningeal Lymphatic Function in Patients with Spontaneous Subarachnoid Hemorrhage.

According to animal studies, glymphatic–meningeal lymphatic dysfunction contributes to poor prognosis and the development of chronic hydrocephalus after subarachnoid hemorrhage (SAH). This study aimed to evaluate glymphatic function and meningeal lymphatic drainage signal in patients with SAH. SAH patients and healthy controls (HCs) were enrolled and underwent multimodal MRI. Glymphatic function was assessed using the diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) index, free water in white matter (FW-WM), and white matter perivascular space volume fraction (PVSVF-WM). The signal intensity (SI) of meningeal lymphatic vessels (mLVs) and deep cervical lymph nodes (dcLNs) was also quantified as an imaging surrogate of meningeal lymphatic drainage. Compared with HCs, SAH patients exhibited significant impairment of glymphatic function, characterized by a reduced DTI-ALPS index, increased FW-WM, and increased PVSVF-WM, along with reduced SI of the mLVs and dcLNs. Patients with chronic hydrocephalus showed even more pronounced impairment than those with acute SAH. Importantly, reduced DTI-ALPS index and mLV SI loss were identified as independent predictors of chronic shunt-dependent hydrocephalus. Notably, 53.8% of chronic hydrocephalus patients exhibited fluid accumulation in the mastoid air cells, inversely correlated with meningeal lymphatic drainage signal. In conclusion, SAH is associated with acute and persistent impairment of glymphatic function and reduced meningeal lymphatic drainage signal, with early MRI-derived metrics serving as potential predictors of chronic hydrocephalus and poor functional outcomes.