Surgery of the Glomus Tympanicum (Glomus Tumor of the Middle Ear)
The size and the extent of the glomus tumor determine the procedure needed. Examination of the eardrum helps the ear surgeon to estimate the size of the tumor. In very early cases, glomus tumors can be as small as 2 to 3 mm. and appear as a red ball behind an intact tympanic membrane (eardrum).
As glomus tumors expand, they begin to fill the middle ear. Some glomus tumors of the middle ear start by growing from the floor of the ear upward. These are the tumors difficult to distinguish from glomus jugulare tumors. A CT scan or other radiologic findings are needed in these cases.
Many glomus tympanicum tumors can now be approached through the ear canal by elevating the eardrum and then destroying the tumor completely with an Argon or CO2 laser versus more radical surgeries performed in the past.
The laser is an extremely useful tool for removing glomus tumors. A larger Argon .4 to .6 mm. fiber is used instead of ordinary fibers used in ear surgery — .2 mm. in diameter. This larger fiber allows for ³blanching² (complete coagulation) of the tumor. As the laser energy is applied to the glomus tumor which is red, this energy is quickly absorbed into the outer pigment of the blood circulating through the tumor. The tumor turns white and succeeding layers of the tumor are vaporized. Along with the laser, we use a suction device which removes the char and smoke. Alternatively, CO2 laser can be utilized to vaporize the tumor (see video below).
Relatively large tumors of the middle ear can be approached by using the Argon or CO2 laser without opening the ear from behind. In using the Argon or CO2 laser, the bones of hearing can be preserved.
Larger tumors may surround the bones of hearing. In these cases, the tumor can be vaporized away from the bones of hearing without separating them in many cases.
Ib. Glomus Tympanicum Extending into Mastoid
When a glomus tumor extends into the mastoid, it becomes necessary to make an incision behind the ear and open the mastoid bone. Every attempt is made to preserve the wall that separates the middle ear from the mastoid. This approach is called an intact canal wall or facial recess approach. The mastoid is completely cleared of disease, judiciously using the laser. The facial nerve is monitored to prevent injury. The entire tumor can be removed in this manner.
Somtimes, the tumor may be attached to the jugular vein as it enters the mastoid bone. In these cases, the tumor must be completely removed from the jugular vein.
Invasion of the Jugular Vein
If the tumor appears to have invaded the jugular vein, then control of the blood vessels of the neck may be necessary with a separate incision in the neck before the tumor can be completely removed. This is the exception in glomus tumors which arise from the middle ear and mastoid, but the usual situation in glomus jugular tumors.
Ic. Invasion of the Brain
If the glomus tumor continues to expand, it may invade the brain through the bone separating the middle ear and mastoid. This bone is called the middle fossa plate, or tegmen.
If the tumor has invaded the bone and entered the brain, intracranial surgical excision of the tumor may be necessary. Depending on the size of the tumor, this part of the surgery is done in conjunction with a neurosurgeon at the peration. It can also be staged and performed at a separate operation. Staging is often chosen when very extensive tumors invade the brain.
Results of removal of glomus tumors of the middle ear and mastoid are extremely good in most cases, less so when the tumor has invaded the inner ear, facial nerve or brain. In long-standing tumors, or in very aggressive glomus tumors, the facial nerve may be invaded by the tumor itself. This condition can make it extremely difficult to separate the tumor from the facial nerve without damaging the facial nerve. In these cases, the canal wall separating the middle ear from the mastoid is generally removed when deeply invaded by tumor. A segment of the facial nerve may be removed and grafted.
II. Surgery of Glomus Jugulare Tumors
A team effort is usually preferred for glomus jugulare tumor surgery. The ear surgeon, the head and neck surgeon, and a neuroradiologist are all needed to remove glomus jugulare tumors.
Prior to surgery, the neuroradiologic evaluation is performed a day or two before surgery. The neuroradiologist (a radiologist who specializes in brain and head x-ray, studies and treatments) also performs an embolization (injection of microscopic sponge material to contain blood supply) of the tumor. The head and neck surgeon, ear surgeon and neurosurgeon, if necessary, perform a combined procedure which isolates the blood vessels in the neck. These feed the tumor. Thus, the removal of the tumor from the middle ear, mastoid and neck can now be done in a single unit. This is called an “enbloc” excision of glomus jugulare tumors. It is the best way to guarantee complete cure.
Although glomus tumors are benign tumors, they grow in extremely delicate areas: near nerves which control swallowing, the vocal cords, and the nerve that controls the facial muscles. Other nerves which also control the shoulder muscle are found in this region.
On our team, the ear surgeon performs the initial portions of the surgery isolating the facial nerve within the mastoid. The nerve is decompressed and taken out of its canal so that it can be preserved during the removal of the tumor. The bone around the capsule of the nerve is thinned using high speed air drills with constant water irrigation. Once the nerve is freed, the head and neck surgeon must identify the vessels in the neck leading to the tumor. The cranial nerves are also identified and tagged. The tumor is then removed. The ear surgeon and head and neck surgeon assist each other. In most cases, it is necessary to tie off or pack the jugular vein in the neck and the mastoid portion of the ear to prevent excessive bleeding at tumor removal.
Successful removal of the tumor may also require delicate dissection of the tumor from the carotid artery. This portion of the procedure is extremely delicate and requires the close cooperation of the head and neck surgeon, ear surgeon and, in some cases, vascular and neurosurgeons.
Using this team approach, the removal of glomus tumors has become a more successful procedure in terms of sparing vital cranial nerves. In addition, blood loss has been brought to a minimum and most patients do not require transfusion.
Glomus tumors are not highly radiosensitive (sensitive to the radiation therapy’s x-rays). However, in older patients, or those who should not undergo surgery, radiation therapy may help to arrest the growth of a glomus tumor. In the younger patient, complete surgical removal of the tumor after embolization is the preferred method of treatment.