Middle Cranial Fossa Approach for Repair of Tegmen Tympani Defects and Temporal Encephalocele

Defects in the floor of the middle cranial fossa (MCF) are commonly reported in cadaveric studies and encountered in surgical practice. Dehiscence of the bone overlying the petrous internal carotid artery (ICA), greater superficial petrosal nerve (GSPN), or geniculate ganglion is reported in 15–20% of cadaveric studies. Defects in the tegmen, if accompanied by dural defects, can result in MCF encephaloceles or cerebrospinal egress into the middle ear, with the risk of seizures, hearing loss, or meningitis. We have adopted an MCF approach to the repair of these dural and tegmen defects with excellent results.

This series of seven individuals presented with middle ear fluid collections associated with subjective hearing loss confirmed by audiometry. Cranial CT or MR imaging demonstrated defects in the tegmen tympani. The average age was 56 years (range, 26–67 years) with a M:F ratio of 6:1. Most defects occurred on the left side. The most common presenting symptoms were ipsilateral hearing loss with ipsilateral otorrhea. All patients were treated via a standard MCF approach and repair of the dural defect with a Durepair (Medtronic) graft and synthetic polymer glue (DuraSeal, Covidien). All cases but one had successful resolution of the CSF otorrhea and improvement in hearing. One patient developed a recurrent CSF otorrhea requiring a repeat surgery and developed delayed staphylococcus aureus meningitis that improved with steroids and antibiotic therapy. Facial nerve monitoring was universal, and there were no instances of facial nerve injury or malfunction. Prophylactic lumbar drain placement was used in the first four patients of the series and was eventually abandoned due to its non-use postoperatively and also to allow a CSF cushion under the temporal lobe during surgery. The middle cranial fossa approach allows for optimal exposure and treatment of CSF leaks due to tegmen defects with excellent outcomes.