Management of Low/Negative Pressure Hydrocephalus: A Systematic Review of Etiology, Pathophysiology, and Treatment.

Negative- and low-pressure hydrocephalus is an uncommon and frequently misdiagnosed condition lacking standardized diagnostic and management protocols. We conducted a systematic review of published studies from 1980 to 2024 to synthesize evidence on etiology, pathophysiology, and treatment. Thirty studies reporting 215 patients were identified, with antecedents including traumatic brain injury, aneurysmal subarachnoid hemorrhage, normal-pressure hydrocephalus, postoperative cases, and spontaneous presentations. Four interacting models were commonly described: viscoelastic brain change with reduced compliance, transmantle pressure gradients, poroelastic or glymphatic dysfunction, and impaired cerebrospinal fluid pulsatility. Management strategies centered on restoring compliance and cerebrospinal fluid pathways through subatmospheric external ventricular drainage, low-pressure or valveless shunting, targeted leak repair, and endoscopic third ventriculostomy. Outcomes were variable, but early recognition and carefully titrated drainage were repeatedly associated with clinical improvement, whereas delayed intervention, infection, and irreversible white-matter injury predicted poor recovery. This review highlights negative- and low-pressure hydrocephalus as a distinct neurosurgical entity and proposes a diagnostic and management framework, while emphasizing the urgent need for multicenter registries with standardized definitions and outcome measures to guide evidence-based care.