Glomus Tumors
Glomus tumors (also known as paragangliomas or chemodectomas) are rare, benign tumors that can develop in several locations in the body including areas in and around the ear. There are two types of glomus tumors related to the ear: glomus tympanicum and glomus jugulare tumors. Although glomus tumors are rare, they are among the most common benign tumors of the ear.
Glomus tumors grow from small collections of nerve-derived cells (glomus cells, also known as glomus bodies). These special cells are found in the walls of certain blood vessels and along nerves. Glomus bodies are chemoreceptors, which means that these cells can detect chemical changes in the blood. Normal glomus cells also make hormones (similar to adrenaline) that can be released into the blood stream.
Glomus tumors are typically slow growing tumors that grow along paths of low resistance. As such, glomus tumors may grow inside nerve canals, along blood vessels, and inside the eustachian tube (the tube that connects the ear to the back of the nose). These tumors also have a very rich blood supply.
Symptoms
Glomus tympanicum tumors develop inside the middle ear. The most common symptom is that of a pulsing sound as blood flows through the vessels of the tumor (pulsatile tinnitus). Other symptoms of a glomus tympanicum include a conductive hearing loss (caused by the tumor blocking sound transmission through the middle ear), ear pain and bleeding from the ear.
Diagnosis
Diagnosis is made based on the patient’s symptoms, physical examination findings and a combination of tests. A common physical examination finding is that of a reddish/bluish mass behind the ear drum (tympanic membrane) (see Figures below). A hearing test and computed tomography scan (CT) are performed routinely. CT is needed to determine the size of a tumor and the relationships of the tumor with structures within the ear. CT tomography is also useful because it can see small erosions or openings in bone.
Treatment
The vast majority of glomus tympanicum tumors are treated with surgical removal. Small glomus tympanicum tumors are removed through incisions confined to the ear canal, while larger glomus tympanicum tumors are removed through an incision behind the ear. Surgical removal of glomus tympanicum tumors is typically performed under general anesthesia on an out patient basis (same day surgery). The chance of recurrence is quite low if the tumor is completely removed.
Symptoms
Glomus jugulare tumors develop from glomus bodies on top of the jugular bulb. The jugular bulb is a region or section of the jugular vein, which is a large vein that drains venous blood from the brain through the neck and into the heart. The jugular bulb is positioned immediately below the middle ear. So, glomus jugulare tumors start their growth under the middle ear. With time, glomus jugulare tumors will often grow into the bottom of the middle ear. Larger tumors may grow around the carotid artery in the skull and even grow into the brain. The symptoms of a glomus jugulare are similar to that of a glomus tympanicum including: pulsatile tinnitus, conductive or mixed hearing loss, ear pain and/or bleeding from the ear. Because of the complex anatomy around the jugular bulb, glomus jugulare tumors may also produce numerous other symptoms.
There are several cranial nerves (nerves that come directly off of the brain) that surround the jugular bulb. Glomus jugulare tumors may compress these nerves. If these cranial nerves are affected, then symptoms of facial weakness, hoarseness, difficulty swallowing, shoulder drooping and/or tongue weakness may develop. A small percentage of glomus jugulare tumors may also produce a large amount of an adrenaline-like hormone (norepinephrine). Norepinephrine can cause symptoms such as anxiety, headache, tremor, flushing, high blood pressure, and a rapid heart rate.
Diagnosis
As with a glomus tympanicum, the diagnosis of a glomus jugulare tumor is made based on symptoms, physical findings, hearing tests and a CT of the ear/temporal bone. Physical examination may also show a reddish/bluish mass behind the ear drum (See figure). In the case of a glomus jugulare, the mass behind the ear drum is really just the “tip of the iceberg”. An MRI is also ordered to examine the size of the tumor in relationship to the surrounding soft tissue of the brain or blood vessels. Blood and urine tests are done to determine if the tumor is secreting adrenaline-like hormones. These “active” tumors are treated with special high blood pressure medications prior to surgery to prevent anesthetic complications.
Angiography (mapping out blood vessels by injecting dye directly into an artery under x-ray visualization) is performed to identify the blood vessels supplying the tumor. Angiography will also determine if the internal carotid artery or internal jugular vein is involved. Angiography also can be used to embolize (intentionally clot) the feeding vessels to decrease tumor bleeding during surgery.
Treatment
Complete surgical removal is the preferred treatment. Radiation or observation may be recommended for elderly patients or patients with poor medical health. Radiation is not recommended routinely because glomus tumors do not respond completely to radiation. Radiation does not remove the tumor. Rather, radiation keeps the tumor from growing by scarring the blood vessels within the tumor. Radiation will also make the tumor more difficult to remove surgically, if the tumor continues to grow. Finally, the radiation can damage the cochlea (the part of the ear that senses hearing) and carries a small risk of causing cancers in the same area many years later.
Glomus jugulare tumors require more extensive surgery than that for glomus tympanicum tumors. This is an exciting time because advances in surgical technique, imaging technology, and interventional radiology over that past three decades have enabled the removal of previously unresectable tumors. Surgery is often performed through incisions extending from the scalp down into the neck. Sometimes the hearing bones are removed, which causes a partial hearing loss. Depending on the size of tumor, structures such as the jugular vein, carotid artery, cranial nerves, eustachian tube, and the temporomandibular joint (jaw joint) may be exposed. Large tumors may also require a craniotomy (exposing the brain) by a neurosurgeon to remove tumor touching the brain. Hospital stay is often several days.
