The term
spontaneous intracranial hypotension (SIH) defines a clinical condition characterized by debilitating postural headaches secondary to spontaneous spinal cerebrospinal fluid (CSF) leak and/or CSF hypotension. According to the
International Classification of Headache Disorders (
ICHD), third edition, SIH is diagnosed when headache has developed spontaneously and in temporal relation to a CSF leak (evident on imaging) and/or CSF hypotension (lumbar puncture opening pressure <60 mm CSF).
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