Outcomes of Middle Fossa Skull Base Defects Repaired Using a Novel Combination of Materials

Introduction: Defects in the middle cranial fossa result in cerebrospinal fluid (CSF) leaks that can present a daunting challenge to skull base surgeons, both in diagnosis and treatment. Defects may arise spontaneously or may be acquired after trauma or surgical manipulations. Persistent leaks require surgical intervention to avoid possibly fatal complications including meningitis and brain herniation. Secondary to the variability in techniques and materials used for repair, outcome analysis has yielded mixed results in the literature. The objective of this study was to evaluate the safety and durability of the authors’ repair technique using a combination of three synthetic materials.

Methods: We performed a retrospective case review of patients treated for CSF leaks between January 2009 and September 2012. Inclusion criteria for the study were: neuroimaging-documented temporal bone defect, gross CSF otorrhea, and symptoms consistent with CSF leak. Ten patients were found to have been treated surgically for middle fossa CSF leaks. Hydroxyapatite cement, collagen-based dural substitute matrix, and polyethylene glycol hydrogel sealant were used in all patients for the repair.

Results: Of the 10 cases that met the inclusion criteria, four were spontaneous defects and six were acquired (one penetrating traumatic brain injury, five with previous surgical procedures). CSF otorrhea was present in nine patients (90%), and hearing loss was present in five (50%). One patient presented with rhinorrhea. Nine cases were repaired via the middle fossa approach, and one case was repaired through a combined middle fossa/transmastoid approach. In all patients, the CSF leaks were successfully repaired using all three synthetic agents with an inlay/onlay technique. The repair was supplemented by autologous graft (temporalis muscle, fascia, or pericranium) in seven cases. Mean follow-up duration was 59.1 weeks (range, 1-180 weeks). In one patient, an epidural hematoma developed at the operative site on postoperative day 7, and in another patient a superficial wound dehiscence occurred on postoperative day 48. There was no evidence of wound infections, neurovascular damage, or CSF leakage requiring reoperation during the follow-up period.

Conclusions: The middle fossa approach using a combination of hydroxyapatite cement, collagen-based dural substitute matrix, and polyethylene glycol hydrogel sealant is a safe, effective method for repairing middle fossa CSF leaks. A multilayered closure remains an important aspect to these closures.