Petrous apex lesions

Petrous apex lesions

Petrous apex lesions are rare disorders of the petrous apex of the temporal bone.

The temporal bone of the skull is shaped like a triangle with the sharp end of the triangle situated deep into the skull towards the brain (see image).

Petrous apex lesions
The petrous apex (white circle).

The petrous apex is the tip of this triangle. Although the petrous apex is made out of bone it contains air pockets, called air cells, lined with mucous membrane. In these spaces there are numerous potential diseases that can occur and cause symptoms. It is also in close proximity of a lot of structures and nerves. As it is so deeply situated in the skull and near the brain a patient may develop different symptoms, all related to all the surrounding nerves.

The symptoms of petrous apex lesions include headaches, facial pain, facial numbness, weakness of mastication, pulsating tinnitus, hearing loss, dizziness, vertigo and facial nerve paralysis and more. With larger lesions, especially tumours, a lot of other symptoms may be present.

Lesions in this area include: cholesterol granuloma, cholesteatoma, mucocele, apicitis, osteomyelitis, radiotherapy for acoustic neuroma, chordoma, meningioma, glomus, chondrosarcoma and aneurism. Most commonly is the so called “leave me alone lesions” of asymmetric development, aeration and fluid accumulation.

The diagnosis of petrous apex lesions depends on imaging which include MRI as well as CT.

Petrous apex lesions
A petrous apex lesion on MRI (yellow arrow)

MRI usually looks at the lesion itself and may help do determine what likely it is. It gives a lot of information on the soft tissue. When CT is ordered the patient must understand that it is not necessarily performed to make a diagnosis but rather to determine the effect and amount of destruction on the surrounding bone the lesion causes. All of this information is then used to predict what lesion or pathological process it is. Due the location, taking a biopsy is not a viable option since this is very difficult and even dangerous.

After consulting with a specialist and when surgery is indicated, different approaches to reach the lesion or tumour is available. It can either be performed via the temporal bone from the side of the head or through the nose. Any of these approaches and options are available and excellent surgeons are available in South Africa to offer this service. If in doubt or requiring a second opinion, feel free to contact the rooms for an opinion.