Middle Cranial Fossa Approach for Repair of Temporal Bone Defects

Temporal bone dehiscence (TBD) refers to a defect in the floor of the middle cranial fossa over the underlying pneumatized skull base, often resulting in leakage of cerebrospinal fluid (CSF) into the middle ear and/or mastoid air cells. TBD can also occur over the superior semicircular canal. While surgical repair is generally the recommended treatment for TBD, there is controversy surrounding which techniques are the safest and most effective. In this retrospective case series, we report our experience in repair of TBD via the middle cranial fossa approach.

Thirty-four patients underwent a total of 37 surgeries during the study period. The average patient age was 52.6 ±  13.9 years. There were 25 females (74%) and 9 males. Obesity was prevalent; 21 patients (61.8%) were obese (body mass index [BMI] > 30 kg/m²), and 7 (20.6%) were overweight (BMI 25–30 kg/m²). The most common presenting symptom was hearing disturbance (70.3%), followed by otorrhea (51.4%). Other presenting symptoms included vertigo/dizziness (29.7%), headache (13.5%), and altered mental status with pneumocephalus (10.8%). Three patients (8.1%) presented with meningitis, and one patient (2.7%) presented with epilepsy. There were bilateral defects in 16 of the 34 patients (47.1%). Empty sella was noted on CT or MRI in 15 patients (45.5%). Descent of the cerebellar tonsils was noted in four patients (12.1%). Six patients (17.6%) had a known diagnosis of OSA. The mean length of stay was 3.97 ±  3.47 days (range: 2–23 days), and the average follow-up time was 19.05 ±  20.80 months (range: 1–76 months). Hearing improved with surgical intervention in 25 of 26 patients with hearing loss as a presenting symptom (96%). Surgery was effective in resolving CSF leak in 18 of 19 cases (95%). There were no iatrogenic postoperative CSF leaks. All four patients who presented with AMS/pneumocephalus had complete resolution of symptoms (100%). All three patients presenting with meningitis had no further episodes (100%). Resolution of vertigo was more variable, with 73% of patients reporting at least minimal improvement. No patients suffered any facial nerve injury. One patient (3%) suffered from dry eye ipsilateral to the MCF repair. One patient (3%) was noted to have a small, clinically silent epidural hemorrhage under the craniotomy site on postoperative CT scan. One patient (3%) had worsening of pre-existing bilateral sensorineural hearing loss on postoperative audiogram.

Patients with TBD often present with symptoms of CSF leak and encephalocele, but may also present with superior semicircular canal dehiscence. Obesity is highly prevalent and likely contributes to the pathogenesis of this disease. The patient’s intracranial pressure status in the setting of TBD may play a role in the presenting symptoms, and intracranial hypotension should be considered in the patient presenting with spontaneous otogenic pneumocephalus. Middle cranial fossa approach using a multilayer repair is highly effective with minimal risk of complications.