Do Most Patients With a Spontaneous Cerebrospinal Fluid Leak Have Idiopathic Intracranial Hypertension?

Background: The association between cerebrospinal fluid (CSF) leaks at the skull base and raised intracranial pressure (ICP) has been reported since the 1960s. It has been suggested that spontaneous CSF leaks might represent a variant of idiopathic intracranial hypertension (IIH). We review the evidence regarding the association between spontaneous CSF leaks and IIH, and the role of ICP in the pathophysiology of nontraumatic skull base defects. We also discuss the management of ICP in the setting of CSF leaks and IIH. Evidence Acquisition: References were identified by searches of PubMed from 1955 to September 2018 with the terms "idiopathic intracranial hypertension" and "cerebrospinal fluid leak." Additional references were identified using the terms "pseudotumor cerebri," "intracranial hypertension," "benign intracranial hypertension," and by hand search of relevant articles. Results: A CSF leak entails the egress of CSF from the subarachnoid spaces of the skull base into the surrounding cavitary structures. Striking overlaps exist regarding demographic, clinical, and radiological characteristics between IIH patients and those with spontaneous CSF leaks, suggesting that some (if not most) of these patients have IIH. However, determining whether a patient with spontaneous CSF leak may have IIH may be difficult, as signs and symptoms of raised ICP may be obviated by the leak. The pathophysiology is unknown but might stem from progressive erosion of the thin bone of the skull base by persistent pulsatile high CSF pressure. Currently, there is no consensus regarding the management of ICP after spontaneous CSF leak repair when IIH is suspected. Conclusions: IIH is becoming more widely recognized as a cause of spontaneous CSF leaks, but the causal relationship remains poorly characterized. Systematic evaluation and follow-up of patients with spontaneous CSF leaks by neuro-ophthalmologists will help clarify the relation between IIH and spontaneous CSF leaks. Address correspondence to Valérie Biousse, MD, Neuro-Ophthalmology Unit, Emory Eye Center, The Emory Clinic, 1365-B Clifton Road NE, Atlanta, GA 30322; E-mail: vbiouss@emory.edu Supported in part by an unrestricted departmental grant (Department of Ophthalmology) from Research to Prevent Blindness, Inc., New York, and by NIH/NEI core grant P30-EY06360 (Department of Ophthalmology). N. J. Newman received the Research to Prevent Blindness Lew R. Wasserman Merit Award. J. M. Levy is supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under Award Numbers UL1TR002378 and KL2TR002381. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors report no conflicts of interest. © 2019 by North American Neuro-Ophthalmology Society

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