Lumbar puncture-induced negative-pressure hydrocephalus in a child with a ventriculoperitoneal shunt and ventricular obstruction: illustrative case.

backgroundNegative-pressure hydrocephalus is a rare form of symptomatic ventriculomegaly characterized by subatmospheric intracranial pressure (ICP). It can occur following lumbar puncture (LP) in patients with impaired CSF dynamics and is frequently mistaken for ventriculoperitoneal (VP) shunt malfunction. OBSERVATIONS: The authors describe the case of a 9-year-old boy with prior medulloblastoma and a VP shunt who presented with neurological decline following LP. Symptoms transiently improved following a large-volume shunt tap, but ventriculomegaly persisted despite shunt revision. ICP monitoring confirmed negative pressure, consistent with post-LP negative-pressure hydrocephalus. Management with an epidural blood patch, neck wrapping, and shunt valve adjustment resulted in clinical and radiographic improvement, notably without the need for prolonged subatmospheric external ventricular drainage. LESSONS: Negative-pressure hydrocephalus should be suspected in patients with a shunt who present with ventriculomegaly, a plausible CSF leak, low-pressure CSF, and poor response to shunt revision. The presence of fourth ventricular obstruction should further heighten suspicion. Effective management involves recognizing altered CSF pressure gradients that mimic high-pressure hydrocephalus, considering epidural blood patch placement to repair CSF leakage, using neck wrapping to augment venous pressure and raise intraventricular pressure to the valve's opening threshold, and avoiding unnecessary shunt revisions or repeat LPs in susceptible patients. https://thejns.org/doi/10.3171/CASE2654.