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[Spontaneous intracranial hypotension with severe headache and typical neuroradiological findings: report of two cases].

Intracranial hypotension causes the postural headache that sometimes follows lumbar puncture. When postural headache and associated symptoms occur after lumbar puncture, the diagnosis is usually obvious. However, similar symptoms may occur after minor trauma or without an obvious precipitating cause (spontaneous intracranial hypotension: SIH). SIH is rare, but is now increasingly recognized as a cause of postural headache. We encountered two cases of SIH showing typical neuroradiological findings. Case 1 is a 47-year-old man who was admitted with severe frontalgia. CT scan revealed vague visualization of bilateral Sylvian fissures and slit ventricles. Spinal fluid pressure was 6cm H2O in the lateral recumbent position. Cerebrospinal fluid (CSF) showed slight lymphocytic pleocytosis. We treated him as having viral meningitis. His headache improved gradually and he was discharged 2 weeks later with slight occipitalgia. One week after discharge, he complained of severe headache again and plain CT showed bilateral subdural hematoma. The subdural hematoma in both sides was evacuated and his headache improved after the operation. Follow-up CT scans two months later showed normalization of ventricle size and cisterns. Case 2 is a 52-year-old woman who was admitted with severe occipitalgia. CT scan on admission showed slit ventricles and the disappearance of the suprasellar cistern and the Sylvian fissure. Spinal fluid pressure was 3cm H2O. Gd-enhanced MRI showed remarkable meningeal enhancement and effacement of the optic chiasm suggesting brain sagging. Her headache improved 2 weeks later after strict bed rest and oral pain relief drugs. The follow-up MRI showed disappearance of abnormal meningeal enhancement and normalization of optic chiasma effacement. SIH is one of the important differential diagnoses of patients complaining of postural headache. Meningeal enhancement of gadolinium-enhanced MRI is an important finding to diagnose SIH. We have to consider SIH when diagnosing postural headache.