Decreased Rate of CSF Leaks after Skull Base Fractures in the 21st Century: A Two-Institution Experience

Introduction: Cerebrospinal fluid (CSF) leaks are among the possible complications in patients with skull base fractures. CSF leaks can lead to meningitis so proper detection and management is crucial. Historically, the literature reports a rate of CSF leaks in skull base fracture patients of 10 to 30%. However, with the advent of advanced imaging modalities, such as thin slice computed tomography (CT) scanning, detection of skull base fractures has become more refined and accessible. A 2013 report from a statewide patient database of over 10,000 patients found a rate of CSF leaks in adult skull base fracture patients of <2%. To investigate further the proposed potential decrease in the rate of CSF leaks, we conduct here an institutional retrospective review.

Methods: A retrospective chart review of two major academic medical centers was conducted for the time period January 2000 through July 2018. Patients with skull base fracture were identified using ICD9/10 codes. Variables included age, gender, CSF leak within 90 days, management regimen (conservative vs. lumbar drain vs. surgical repair), meningitis within 90 days, and 1-year mortality. When ICD9/10 codes did not indicate CSF leak, but did indicate meningitis, lumbar drain, and/or surgical repair, CSF leak was considered to be present. Patients under the age of 18 years were excluded from analysis. Analysis was done in R v.3.0.1 software.

Results: Overall, there were 4,944 patients with skull base fractures, of which 202 (4.1%) developed a CSF leak within 90 days. Mean age was 49.2 (±21.9) years and 1,586 (32%) were female. Age distribution is given in [Fig. 1]. Incidence of skull base fractures by year is given in [Fig. 2]. Among CSF leaks, 85 (42%) were conservatively managed, 104 (52%) were treated with lumbar drain, and 12 (6%) required surgical repair. Meningitis developed within 90 days in 58 (29%) patients. Among meningitis patients, 32 were conservatively managed, 23 required lumbar drain, and 3 required surgical repair. The 1-year mortality for all skull base fracture patients was 535 (11%), for patients with CSF leaks was 23 (11%), and for patients with meningitis was 9 (16%).

Conclusion: In this 18-year, two-institution retrospective review of 4,944 skull base fracture patients, we found the rate of CSF leaks to be 4.1%. This is lower than the historically-cited range of 10 to 30%. Given the increased incidence of skull base fractures over recent decades, as illustrated in [Fig. 1], this decreased rate of CSF leaks may actually represent a relative decrease. This may be an effect of the advances in modern imaging modalities making it easier to more readily detect and diagnose skull base fractures. The rate of meningitis in this population was 29%, and for those who developed meningitis the 1-year mortality was 16%. This suggests that while the relative rate of CSF leaks may be decreasing in the skull base fracture population, they remain a clinically important complication.

Fig. 1 Age distribution of skull base fracture patients.

Fig. 2 Incidents of skull base fractures by year 2000 to 2007.

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