With some exceptions, especially in earlier reports in which the terms “spontaneous” and “nontraumatic” CSF leaks were used interchangeably ( 8– 13), most authors now refer to spontaneous CSF leaks as CSF leaks of unknown origin.
In the original classification( 1), high-pressure CSF leaks only included those secondary to tumors and hydrocephalus, and IIH was not mentioned. CSF leaks can be traumatic (80%) or nontraumatic (20%), the latter further subdivided into normal-pressure or high-pressure CSF. In this article, the term “CSF leak” will refer to CSF leaks at the skull base unless otherwise specified.ĬSF leaks have been variously classified in the literature, but the general principles of a categorization based on mechanisms as developed by Ommaya et al ( 1) are widely accepted. Spinal CSF leaks have only rarely been associated with intracranial hypertension ( 7) and will not be further discussed. Although most patients with CSF leaks at the level of the spine have symptoms of intracranial hypotension ( 5, 6), those with CSF leaks at the level of the anterior or middle skull base often present with isolated clear fluid leakage (rhinorrhea or otorrhea). We also discuss the management of ICP in the setting of CSF leaks and IIH.ĭEFINITION AND CLASSIFICATION OF CEREBROSPINAL FLUID LEAKSĪ CSF leak entails the egress of CSF from the subarachnoid spaces of the anterior or middle skull base into the surrounding sinonasal or middle ear cavities through a dehiscence of the lamina dura. We review the evidence regarding the association between spontaneous CSF leaks, IIH, and ICP in the pathophysiology of nontraumatic skull base defects. This highlights the need for IIH specialists to become more knowledgeable regarding spontaneous CSF leaks. Surprisingly, although IIH is routinely diagnosed and managed by neuro-ophthalmologists, very few studies regarding CSF leaks in IIH patients have been published in the ophthalmology or neurology literature ( 3, 4). In these patients, the leak acts as a “natural” CSF diversion, and these patients usually do not develop the typical symptoms and signs of intracranial hypertension. Therefore, spontaneous CSF leaks might be a presentation of idiopathic intracranial hypertension (IIH). In the 1990s, otorhinolaryngologists ( 2) emphasized that spontaneous CSF leaks might represent a subset of high-pressure CSF leaks. In the 1960s, Om-maya et al ( 1) suggested that nontraumatic CSF leaks should be categorized into those related to high ICP or normal ICP. The association between cerebrospinal fluid (CSF) leaks at the skull base and raised intracranial pressure (ICP) has been reported for more than 5 decades in the otorhinolaryngology and neurosurgery literature.
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