Abstract
We report a case involving a cholesterol granuloma of the petrous apex that was drained using the infra-labyrinthine approach.
A 16-year-old boy presented with complaints of severe headache that was not relieved by painkillers. Computed tomography (CT) scan revealed an isodense mass in the right petrous apex. On magnetic resonance imaging (MRI), T1-weighted images of the mass showed heterogeneous iso- to hyperintensity whereas T2-weighted images showed homogeneous hyperintensity, and the mass was not enhanced after gadolinium administration. A non-echo planar diffusion-weighted MR image (non-EP DWI) did not reveal hyperintensity in the mass. The mass was diagnosed as a cholesterol granuloma of the right petrous apex. The patient did not suffer from hearing loss, dizziness, facial palsy, or any other neurologic defects. The severe headache was the sole symptom noted.
Surgery was performed using the infralabyrinthine approach without any complications such as facial palsy, hearing loss, dizziness, or cerebrospinal fluid leakage. A drainage tube was indwelled between the petrous apex and mastoid cavity.
After surgery, his headache improved; however, mild recurrence was observed three months later. CT revealed a scar tissue in the mastoid cavity, which obstructed the drainage tube. The mastoid cavity was cleaned under local anesthesia, and his headache improved further.
The aims of petrous apex cholesterol granuloma surgery are drainage and aeration. Multiple approaches have been described for treating these lesions, such as middle cranial fossa, retrosigmoid, transotic/ translabyrinthine, infralabyrinthine, infracochlear, and transsphenoidal approaches. The approach selected depends on the patient's inner ear and facial nerve function, position of the blood vessels, and the site and extent of the lesion. Since the drainage route created during this approach is relatively narrow, recurrence is often observed. Therefore, further studies are required to develop an effective method to create a continual drainage route.
