Idiopathic Intracranial Hypertension Presenting as Spontaneous CSF Leak

Introduction: Spontaneous cerebrospinal fluid (CSF) leaks may represent a unique clinical presentation of idiopathic intracranial hypertension (IIH), secondary to skull base erosion from chronically elevated CSF pressures. However, patients with spontaneous CSF leaks may not present with the classical symptoms of IIH, including severe headaches, papilledema, elevated opening pressures, and slit ventricles on imaging. As such, we retrospectively reviewed our own recent institutional experience and performed a literature review to further characterize patients presenting with spontaneous CSF leak and previously undiagnosed IIH.

Methods: Following a single-institution retrospective review of the last five patients treated for spontaneous CSF leak with delayed measurement of opening pressures after leak repair, we performed a systematic literature review of spontaneous CSF leak in patients previously undiagnosed with IIH, utilizing a PubMed query of “CSF leak,” and “hypertension.”

Results: Including our last five patients, the literature review yielded 21 total studies, comprised of 476 total patients meeting criteria for presentation with spontaneous CSF leak without prior history of IIH. Patient demographics included an average age of 52.1 years, 84.8% female predominance, and an average body mass index of 27.8. Out of 322 patients with available data, presenting symptoms in addition to CSF leak included significant headaches (38.5%), visual disturbances (6.5%), and signs of meningitis (6.5%). Out of 101 patients undergoing formal ophthalmologic examination, papilledema was reported in 18.8% of patients. Radiographic findings revealed empty sella in 58.9% of 331 patients and normal ventricular configuration (i.e., absence of slit ventricles) in 96.5% of 57 patients with available imaging for review. Opening pressures measured either at time of CSF leak repair or in the immediate postoperative period demonstrated an average of 21.7 cm H₂0 among 427 patients with available data. While the majority of patients underwent medical treatment postoperatively with acetazolamide, 14.3% of patients were ultimately treated with a ventriculoperitoneal shunt, due to recurrent CSF leak, significantly elevated opening pressures post-CSF leak repair, and/or intolerance of acetazolamide therapy.

Conclusion: An underlying diagnosis of IIH must be strongly suspected in patients presenting with spontaneous CSF leaks. Our experience and review of the literature suggests that these patients may present differently from typical IIH patients, including absence of a significant headache history and lack of subjective or objective evidence of visual deficits. Opening pressures may range from normal to mildly elevated ranges, reflective of attenuation of intracranial hypertension via the CSF leak. In addition, in contrast to slit ventricle morphology characteristic of typical IIH, imaging in these patients may reveal a normal ventricular configuration, as well as an empty sella, the latter reflective of long-standing undiagnosed intracranial hypertension. At our institution, we routinely perform a delayed measurement of opening pressure within 1 to 3 months after spontaneous CSF leak repair to evaluate for IIH. Additionally, all patients should undergo neurovascular imaging to rule out cerebral venous thrombosis. While medical therapy with acetazolamide for IIH is commonplace, definitive treatment via permanent CSF diversion or venous stenting may be indicated in patients exhibiting significantly elevated opening pressures postoperatively, or experiencing recurrent CSF leaks.