Glomus tumors are rather common, benign tumors of the middle ear which arise from glomus bodies. Glomus bodies are tiny, normal structures in the middle ear which serve as baro receptors. These baroreceptors sense and help to regulate the oxygen pressure in the middle ear and mastoid. Glomus tumors are also called paraganglioms and chemodectomas. Glomus tumors in the middle ear are commonly called glomus tympanicum tumors, and glomus tumors of the jugular vein are referred to as glomus jugulare tumors.
Benign tumors of glomus bodies can occur within the middle ear or at other sites: the temporal bone and neck, or within the jugular vein (the large vein in the upper neck which drains the head toward the heart). Glomus tumors of the middle ear are more common than glomus tumors of the jugular vein. They can result from abnormal growth of a single glomus body.
Glomus tumors are highly vascular and are primarily composed of blood channels flowing through the tumor itself. They appear red on examination of the eardrum. Most glomus tumors are readily noted by a primary care physician's routine examination of the ear. They appear as a red ball or mass behind the eardrum. The eardrum may pulsate, if the glomus tumor is touching the under surface of the intact eardrum.
This symptom is called pulsatile tinnitus. Most patients with glomus tumors of the middle ear can hear a pulsing sound in the ear on the side which has the tumor. Pulsatile tinnitus occurs as the tumor enlarges and presses against the bones of hearing. It is the actual pulsation of blood which distorts the movement of the bones of hearing.
Glomus tumors can grow very large. As the glomus tumor of the middle ear expands, it can grow into the mastoid itself or through the wall that divides the middle ear from the mastoid and deeply infiltrate the bone. The tumor may also wrap around and infiltrate areas around the facial nerve, as it enlarges. It can become attached to the jugular vein and carotid artery. In these cases, the tumor is more difficult to remove and radical surgery is necessary.
If the glomus tumor fills the middle ear space, hearing loss becomes a prominent symptom. However, in small glomus tumors of the middle ear, hearing can be quite normal and there may be no symptoms at all. The tumor itself is often identified on routine exam as being a red spot behind the eardrum. The size and extent of the glomus tumor of the middle ear can be well assessed by microscopic examination. Additional medical imaging studies are necessary to define the tumor.
Depending on the size and location of the glomus tumor, treatment requires careful planning. This may require preoperative embolization of the tumor to decrease blood loss during surgery. Small tumors of the middle ear can be removed with outpatient surgery. Larger tumors require longer surgeries and hospital stays, and commonly the cooperation of a skull base team. Radiosurgery may be an appropriate adjunctive treatment in certain select cases.