Transcanal Endoscopic Infracochlear Approach for a Petrous Apex Cholesterol Granuloma

By June 7, 2019

Deep, Nicholas1; Taufique, Zahrah1; Jethanamest, Daniel1
1 Department of Otolaryngology- Head & Neck Surgery, NYU Langone Health, New York, NY, USA

We present a case of a petrous apex cholesterol granuloma (PACG) managed via a transcanal endoscopic infracochlear approach and highlight the anatomic features that make this approach desirable over other approaches. We describe important intraoperative landmarks to permit safe access to the petrous apex.

Case report

A 51-year-old male presented with headaches and vertigo lasting several hours. He denied other neurotological symptoms. CT scan demonstrated an expansile lesion within the right petrous apex with erosion into the IAC and compression of the horizontal petrous carotid artery. MRI demonstrated a hyperintense lesion on T1 and T2 consistent with a PACG.  Audiogram confirmed serviceable hearing.  Since the petrous apex was not in direct contact with the posterior wall of the sphenoid sinus, a transsphenoidal approach was less feasible. A low-lying jugular bulb made the infracochlear air cell tract very accessible. Therefore, a transcanal endoscopic infracochlear approach was performed with successful drainage and wide marsupialization of the PACG.

The endoscopic infracochlear approach is indicated in patients with PACG and serviceable hearing. A low-lying jugular bulb makes this approach exceptionally suitable as it permits the creation of a large corridor that will remain patent and allow for aeration, which reduces the risk of recurrent PACG formation. The excellent visualization provided by the endoscope allows for the detection of subtle color changes in the bone, thereby permitting safe drilling in the infracochlear triangle. Identification of the round window, finiculus, Jacobson’s nerve, and subcochlear canaliculi are helpful landmarks to orient the surgeon when accessing the petrous apex.