An Unusual Case of Spontaneous Intracranial Hypotension Presenting as Meningoencephalitis

Spontaneous intracranial hypotension (SIH) is a rare, underdiagnosed cause of secondary headache due to cerebrospinal fluid (CSF) leakage. While typically presenting with orthostatic headache, atypical manifestations may mimic infectious or inflammatory diseases.

A 45-year-old man presented with acute alteration of consciousness, expressive aphasia, and nuchal rigidity after 1 month of orthostatic occipital headache. Brain magnetic resonance imaging (MRI) showed diffuse pachy- and leptomeningeal enhancement initially interpreted as infectious meningoencephalitis. Lumbar puncture revealed turbid, blood-stained CSF with elevated protein and neutrophilic pleocytosis, but microbiological and autoimmune studies were negative. Neurological symptoms improved with conservative management (bed rest, hydration, analgesia), and follow-up imaging confirmed full resolution. Retrospective neuroradiological review reclassified findings as SIH.

SIH can mimic infectious meningoencephalitis both clinically and in CSF appearance. Recognition of preceding orthostatic headache and characteristic MRI features is essential to avoid unnecessary antimicrobial therapy and invasive diagnostic procedures.

Spontaneous intracranial hypotension may present atypically, mimicking infectious meningoencephalitis.In any acute neurological presentation, a preceding history of orthostatic headache should prompt reconsideration of spontaneous intracranial hypotension before performing lumbar puncture.Magnetic resonance imaging meningeal enhancement is nonspecific; careful correlation with clinical features and exclusion of infectious or autoimmune causes are essential for accurate diagnosis.