Cholesterol granulomas are rare, benign cysts that can occur at the tip of the petrous apex, a part of the skull that is next to the middle ear. The cysts are expanding masses that contain fluids, lipids, and cholesterol crystals surrounded by a fibrous lining.
Granulomas can occur throughout the body as a reaction to foreign material. They usually have no symptoms or serious effects. However, cholesterol granulomas of the petrous apex are dangerous because of their proximity to the ear and several important nerves. Permanent hearing loss, nerve damage, and bone destruction can occur if the mass is left untreated and continues to expand.
Cholesterol granulomas can form when the air cells in the petrous apex are obstructed. The obstruction creates a vacuum that causes blood to be drawn into the air cells. As red blood cells break down, cholesterol in the hemoglobin is released. The immune system reacts to the cholesterol as a foreign body, producing an inflammatory response. Associated small blood vessels rupture as a result of the inflammation. Recurrent hemorrhaging makes the mass expand.
The surgical approach depends on the location of the cyst and the status of the patient's hearing. At UPMC, the preferred surgical approach for cholesterol granulomas is the Endoscopic Endonasal Approach (EEA). This innovative, minimally invasive technique uses the nose and nasal cavities as natural corridors to access hard-to-reach or previously inoperable tumors. EEA offers the benefits of no incisions to heal, no disfigurement to the patient, and a faster recovery time.
Your physician will ask you about symptoms that you might be experiencing.
Symptoms may include:
- hearing loss in one ear
- tinnitus (ringing in the ears)
- facial twitching
- facial numbness
Upon examination of the ear with an otoscope, the eardrum may appear blue, or a brownish protrusion behind it may be evident.
Imaging studies such as MRI and CT scans aid in differentiating the cholesterol granuloma from other lesions. These studies also are useful for revealing the granuloma and in revealing its size and precise location.
Audiograms may be used to assess hearing loss.
Treatment involves drainage and ventilation of the cholesterol granuloma. In cases where the granuloma is particularly large and destructive, complete removal may be necessary. Access to the petrous apex is difficult and requires special surgical skills. The approach used depends upon the location of the mass, the skills of the surgeon, and the status of the patient's hearing.
Cholesterol granulomas of the petrous apex, particularly those with growth in the direction of the clivus, with midial expansion or with inferior expansion under the level of the internal carotid artery, can be reached directly through the Endoscopic Endonasal Approach (EEA). This state-of-the-art, minimally invasive surgical procedure uses the nose as a natural corridor to reach these lesions. There are no incisions in the skin of the face or head. In addition to being minimally invasive, EEA also preserves hearing.
Hearing may also be preserved with the infralabyrinthine or infracochlear approaches.
The translabyrinthine approach, in which an incision is made behind the ear, is rarely used. It is generally used for patients who already have severe hearing loss, as it results in complete sensorineural loss of hearing.