Spontaneous intracranial hypotension is a condition caused by low cerebrospinal fluid (CSF) pressure. Reduction in CSF pressure results in the brain sagging, increasing traction of brain structures, meninges, and blood vessels, which leads to orthostatic headaches. The causes of reduced CSF pressure are most commonly secondary to procedures (such as persistent dural leak following a lumbar puncture), trauma, or overdrainage of CSF from a shunt. Spontaneous intracranial hypotension occurs due to CSF leakage, most commonly through damaged or weakened dura. CSF leaks are more common in patients with connective tissue disorders that predispose them to dural weakness. Minor trauma, often not recognized by the patient, may cause rupture of an epidural or perineural cyst or a dural tear through which CSF can leak. Additionally, bone spurs and degenerative osseous disease of the spine have been implicated in causing spontaneous intracranial hypotension. Most CSF leaks are localized to the spine. Spontaneous intracranial hypotension can affect patients of all ages, with a median age at diagnosis of 40 years. Females are twice as likely to be affected than males (2:1).
Patients classically present with orthostatic headaches that improve while supine and worsen with standing. Headaches may be accompanied by nausea, vomiting, tinnitus, dizziness, and/or neck pain. Patients typically have a normal neurologic examination, although complications including cognitive deficits, ataxia, movement disorders, quadriparesis, and cerebral hemorrhage can occur in severe cases.
Diagnosis of spontaneous intracranial hypotension is made when patients have orthostatic headaches with evidence of a CSF leak on imaging or low CSF pressure.