Cerebrospinal fluid (CSF) leaks are increasingly considered an important cause of low-pressure headaches, particularly among younger patients . While rigorous epidemiological evidence is lacking, several series have documented the relative incidence of CSF leak from varying etiologies. Approximately 80% of CSF fistulae with rhinorrhea have been reported to be caused by nonsurgical trauma and 16% by surgical trauma, with the remaining 4% having nontraumatic etiology . Of course, for patients with spontaneous intracranial hypotension, the underlying CSF leak should be looked for in the spine and not at the level of the skull base . Spontaneous intracranial hypotension has been estimated to range between 1 per 50 000 to 5 per 100 000 persons in community-based and emergency department based settings, respectively [4,5]. Spontaneous intracranial hypotension affects women twice as frequently as men and typically presents in the fourth or fifth decade of life, though the specific pathophysiological reason for this demographic trend is currently unknown [6–16]. Pathogenesis The specific etiology underlying spontaneous CSF leaks remains largely unknown, but underlying structural weakness of the spinal meninges is suspected, though a history of trauma may be elicited in up to a third of patients [14,17–19]. This dural weakness, ranging from simple dural tears to meningeal diverticula, allows CSF to leak into the epidural [20,21]. Ventral spinal CSF leaks are often seen at the level of the disk space and may be associated with degenerative disk disease.
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