Learn more about petrous apex lesions and how they are treated.
The petrous apex refers to a portion of the temporal bone situated approximately two to three inches in from the outer portion of the ear. Fluid-filled cysts, cholesteatomas, cholesterol granulomas, and other types of lesions may develop on the petrous apex and require medical intervention.
These lesions are often benign
However, location of the petrous apex can make surgical treatment complicated
The exact cause of some petrous apex lesions is not clear. It is believed that cholesterol granulomas may develop as the result of air infiltrating the bone marrow and creating pockets that then fill with blood and trigger the formation of a cyst. Cholesterol granulomas may also be linked to dysfunctions involving the Eustachian tube. The purpose of the Eustachian tube, which connects the tympanic cavity to the back of the nose, is to allow air to enter behind the eardrum while also allowing fluid and mucus to drain.
Cholesteatomas involving the petrous apex may be congenital, meaning the condition is present at birth, or it may be acquired during the patient’s lifetime. Congenital cholesteatomas are typically caused by skin cells left behind during embryonic development. The body responds by encapsulating these cells in a skin cyst known as a cholesteatoma. Acquired cholesteatomas are normally caused by Eustachian tube dysfunction, chronic ear infections, fluid that becomes trapped in the inner ear, or trauma to the ear. It is common for cholesteatomas to develop in a vacuum created in the Eustachian tube following a perforated eardrum. Both congenital and acquired cholesteatomas can become quite large and impinge on nerves and other nearby structures.
Symptoms of Petrous Apex Lesions
Small petrous apex lesions may not cause any issues or symptoms. Problems may arise when the lesions grow and impinge on other facial structures, including the ears, eyes, and facial nerves. A lesion impinging on the various facial nerves may affect sensations in the face or impact eye movement. Other symptoms may include a feeling that the ear is plugged up, foul smelling drainage coming from the ear, decreased hearing, balance issues, and pain behind the ear.
A doctor will typically arrive at a preliminary diagnosis of a petrous apex lesion based on the patient’s symptoms and the results of an initial evaluation. Computed tomography or magnetic resonance imaging scans are normally used to confirm the diagnosis and to determine the best treatment approach.
Treating Petrous Apex Lesions
The treatment of petrous apex lesions depends on the type of lesion, the severity of the patient’s symptoms, and the amount of damage that the growth has caused to the surrounding structures of the ear. Cholesterol granulomas affecting the petrous apex are fluid-filled cysts, so the primary treatment involves draining the cyst. There are a number of different approaches that the surgeon may use to access the cyst; however, the most frequently used technique is the infracochlear approach. This technique involves accessing the granuloma from a position just below the cochlea of the inner ear.
Petrous apex cholesteatomas, on the other hand, are a little more complicated since they must be completely removed. Although it is possible to access the cholesteatoma through the inner ear, it is sometimes also necessary to access it through the middle fossa located below the brain. It is possible for cholesteatomas to become so large that they break or otherwise damage the delicate bones of the middle ear. In this case, an additional surgery may be required to repair the damage once the cholesteatoma is removed.
What to Expect Following Treatment
It is normal to for the ears to feel full or plugged up for a few weeks following the procedure. Most patients find that their normal hearing returns and that they are able to return to their normal activities free of any symptoms.
Avoiding Petrous Apex Lesions
In many cases, such as with congenital cholesteatomas, there is nothing that a person can do to prevent a petrous apex lesion. The key is to seek medical attention as soon as possible after symptoms develop. Individuals should consult their doctor if they experience:
• Recurrent or chronic ear infections
• Changes in their hearing
• Issues maintaining balance
• Pain in or around their ear
• Drainage from the ears
• Trauma to the ears
• Changes in sensation or movement of the facial muscles