Normal pressure "herniation"

Introduction: Hydrocephalus with normal intracranial pressure has rarely been reported to result in herniation. Methods: Case report. Results: A 52-year-old man became acutely comatose with extensor posturing and ventriculomegaly 17 days after experiencing a primary ventricular hemorrhage. An external ventricular drain revealed normal intracranial pressure. After 24 hours without improvement with the drain set at a level of 5 mm H₂O, negative-pressure siphoning (50 mL of cerebrospinal fluid [CSF] removed) reduced ventricular size and led to dramatic clinical recovery. Conclusion: Normal pressure hydrocephalus can result in delayed brainstem herniation after ventricular hemorrhage. CSF siphoning in these patients can reverse the syndrome.