Spontaneous Cerebrospinal Fluid Leaks from Multiple Anterior and Lateral Skull Base Defects

Introduction: Spontaneous cerebrospinal fluid (CSF) leaks are frequently idiopathic and appear to develop in part from elevated intracranial pressure (ICP). As this pressure is diffused throughout the cranial cavity, it is possible to develop CSF leaks in multiple locations. There are a limited number of studies on this particular situation, in which multiple defects and sites of CSF leak are present. We intend to evaluate the characteristics of this population and assess outcomes after surgical repair.

Methods: A retrospective chart review from 2014 to 2019 was performed at a tertiary medical center. Patients 18 years or older with a diagnosis of spontaneous CSF leak were eligible for study inclusion. History of skull base trauma, diagnosis of a neoplasm, chronic inflammatory disease, or iatrogenic CSF leaks were excluded. From this cohort, patients with multiple skull base defects, defined as more than one skull base defect separated by intervening bone occupying different anatomical areas in either the lateral skull base, anterior skull base, or both, were included for further analysis. Anterior and lateral skull base thickness was measured on computed tomography scans using previously defined methodologies; these values were compared with those from a cohort of single-site CSF leak patients matched for BMI.

Results: Review of our institutional experience in the past 5 years revealed a total of 292 patients with a diagnosis of spontaneous CSF leak, from which 11 (3.8%) had multifocal CSF leaks. Age did not differ between the single site and multiple site CSF groups (p = 0.36). Body mass index, however, was significantly higher (31.5 ± 0.5 vs. 46.2 ± 2.9, p < 0.0001) in the multifocal leak cohort. Furthermore, there was a higher prevalence of women (p = 0.012) and African Americans (p = 0.003). The average anterior and lateral skull base thickness in the multifocal leak cohort measured 3.5 ± 0.47 and 4.1 ± 0.43, respectively; this was not found to differ significantly from BMI-matched patients who had only one site of skull base defect and CSF leak (p = 0.56). Of the 11 patients, 4 had multiple distinct anterior skull base defects, 4 had multiple distinct lateral skull base defects, and 3 presented with a combination of anterior and lateral skull base defects. The overall success rate of repair of CSF leak was 95%; one patient experienced a recurrent leak after initial surgery. Three patients required placement of a ventriculoperitoneal shunt due to the onset of severe headaches or blurry vision after surgery. Interestingly, 50% of patients endorsed the onset of nonsevere headaches or blurry vision after surgical repair. No association between the risk of headache after repair and BMI was noted (p = 0.39).

Discussion: The data support an increased incidence of multiple skull base defects with distinct site of CSF leak in more obese subjects. African American women also had a higher risk. Surgical repair in patients with multifocal CSF leaks remains highly successful (95%) with low recurrence rates similar to that observed in the single-site CSF leak cohort. Patients with multifocal leaks are at high risk of developing symptoms such as headaches or blurry vision, suggestive of elevated ICP postoperatively.