[Consensus on the diagnosis and treatment of low-pressure hydrocephalus(2025 edition)].

Low-Pressure Hydrocephalus (LPH) is a distinct type of hydrocephalus characterized by persistently low intraventricular pressure below 70 mmH₂O (1 mmH₂O=0.009 8 kPa). Its pathophysiological mechanisms and treatment strategies differ significantly from normal-or high-pressure hydrocephalus, with fourth ventricular outflow tract obstruction and altered brain compliance potentially serving as critical pathogenesis. LPH predominantly occurs in patients with severe consciousness impairment, typically secondary to severe neurological conditions such as severe brain injuries or chronic intracranial infections. Given that the LPH usually has a long course of primary disease and insidious onset, it was poorly diagnosis and get insufficient recognition in clinic. To date, there is no accurate epidemiology of LPH, and existing studies suggest that its actual incidence may be systematically underestimated. To standardize the early identification, precise diagnosis and reasonable intervention of LPH and improve the treatment effect, the Chinese Neuroscience Society organized experts in related fields to formulate the "Consensus on the diagnosis and treatment of low pressure hydrocephalus（2025 edition）", based on the latest evidence-based medicine and specific practices in the diagnosis and treatment of LPH. The diagnosis of LPH is confirmed based on: (1) high-risk clinical history; (2) progressive ventricular enlargement accompanied by worsening neurological deficits: (3) characteristic imaging findings (ventricular system dilation, disappearance or marked narrowing of sylvian fissure cisterns and convexal subarachnoid spaces, fourth ventricular enlargement potentially demonstrating a "ball sign"); (4) ventricular puncture confirming pressure between 0 to <70 mmH₂O. For LPH management, ventriculoperitoneal shunt placement using non-antisiphon devices is recommended as the primary treatment. This should be combined with dynamic progressive valve pressure adjustments guided by serial imaging of ventricular morphology and neurological status, ultimately achieving personalized target pressure levels to ensure effective cerebrospinal fluid diversion and improved clinical outcomes.