Spontaneous intracranial hypotension is caused by spontaneous spinal cerebrospinal fluid (CSF) leaks and is known for causing orthostatic headaches. It is an important cause of new headaches in young and middle-aged individuals, but initial misdiagnosis is common.
To summarize existing evidence regarding the epidemiology, pathophysiology, diagnosis, and management of spontaneous spinal CSF leaks and intracranial hypotension.
MEDLINE (1966-2005) and OLDMEDLINE (1950-1965) were searched using the terms intracranial hypotension, CSF leak, low pressure headache, and CSF hypovolemia. Reference lists of these articles and ongoing investigations in this area were used as well.
Spontaneous intracranial hypotension is caused by single or multiple spinal CSF leaks. The incidence has been estimated at 5 per 100 000 per year, with a peak around age 40 years. Women are affected more commonly than men. Mechanical factors combine with an underlying connective tissue disorder to cause the CSF leaks. An orthostatic headache is the prototypical manifestation but other headache patterns occur as well, and associated symptoms are common. Typical magnetic resonance imaging findings include subdural fluid collections, enhancement of the pachymeninges, engorgement of venous structures, pituitary hyperemia, and sagging of the brain (mnemonic: SEEPS). Myelography is the study of choice to identify the spinal CSF leak. Treatments include bed rest, epidural blood patching, percutaneous placement of fibrin sealant, and surgical CSF leak repair, but outcomes have been poorly studied and no management strategies have been studied in properly controlled randomized trials.
Spontaneous intracranial hypotension is not rare but it remains underdiagnosed. The spectrum of clinical and radiographic manifestations is varied, with diagnosis largely based on clinical suspicion, cranial magnetic resonance imaging, and myelography. Numerous treatment options are available, but much remains to be learned about this disorder.