Microsurgical resection of Acoustic Neuroma is a highly complex procedure. While we cannot predict every complication that might occur, a list follows, including some very unlikely potential effects. In general, the smaller the tumor at the time of surgery the less potential that a complication will arise. As the tumor enlarges, the incidence of complication becomes greater.
In small tumors it is sometimes possible to save hearing by removing the tumor. Most tumors are larger, however, and the hearing is lost in the involved ear as a result of the surgical procedure. Therefore, following surgery the patient hears only with the remaining good ear. However, there are now new techniques to help cross the sound over from the deaf ear to the “good ear” such as CROS hearing aid or a Bone Anchored Hearing Aid (BAHA).
Tinnitus (ear noise) can be very bothersome in the ear of patients with Acoustic Neuroma. In many cases after treatment of Acoustic Neuroma, tinnitus remains the same as before surgery. Some patients may notice that tinnitus is improved after removing the tumor. In 10% of the patients the tinnitus may be more noticeable.
Taste disturbance and mouth dryness are not uncommon for a few weeks following surgery. In 5% of patients this disturbance is prolonged.
In Acoustic Neuroma surgery it is necessary to remove part or all of the balance nerve and, in some cases, to remove the inner ear balance mechanism. Because the balance nerve usually has been damaged by the tumor, its removal frequently results in improvement in any preoperative unsteadiness. Dizziness may occur, nonetheless, following surgery and may be severe for days or a few weeks. Imbalance is prolonged in 30% of the patients until the normal balance mechanism in the opposite ear compensates for the loss in the operated ear. Some patients notice unsteadiness for several years, particularly when fatigued, though this is not very common.
Acoustic tumors are in intimate contact with the facial nerve, the nerve which controls movement of the muscles which close the eyelids as well as the muscles of facial expression. Temporary paralysis of the face and muscles which close the eyelids is common following removal of an Acoustic Neuroma. Weakness may persist for six to twelve months and infrequently there may be permanent residual weakness.
Facial paralysis may result from nerve swelling or nerve damage. The facial nerve is usually compressed and distorted by the tumor in the internal auditory canal. Careful tumor removal usually results in preservation of the nerve but nerve stretching may result in swelling of the nerve with subsequent temporary paralysis. In these instances facial function is observed for a period of months following surgery. If it becomes certain that facial nerve function will not recover, a second operation may be performed to connect the facial nerve to a nerve in the neck.
During the entire surgery, special nerve monitoring of the facial nerve is performed to lessen the possibility of damage to the nerve. This nerve monitoring has improved facial nerve outcomes and is utilized throughout the case to map out the facial nerve and ensure it’s safety.
Should facial paralysis develop the eye may become dry and irritated. Care by an eye specialist may be indicated. We often recommend artificial tears eye drops and sometimes recommend taping the eye shut at night. When prolonged facial nerve paralysis is expected, implantation of a gold weight or spring into the eyelid helps keep the eye moistened as well as providing comport and improved appearance.
Acoustic Neuroma may contact the nerves which supply the eye muscles, the face, the mouth and throat. These areas may be injured with resultant double vision, numbness of the throat, weakness of the face and tongue, weakness of the shoulder, weakness of the voice and difficulty swallowing. These problems may be permanent.
Acoustic Neuroma are located adjacent to vital brain centers which control breathing, blood pressure and heart functions. As the tumor enlarges it may become attached to these brain centers and usually becomes intertwined with the blood vessels supplying these areas of the brain.
Careful tumor dissection, with the help of an operating microscope, usually avoids complications. If the blood supply to vital brain centers is disturbed, serious complications may result: loss of muscle control, paralysis, even death.
Acoustic Neuroma surgery may result in a temporary leak of cerebrospinal fluid (fluid surrounding the brain). This leak is closed prior to the completion of the surgery with fat removed from the abdomen, most often. This typically seals the leaking of spinal fluid however occasionally a leak may occur after surgery and a further procedure may be necessary to seal the leak.
Bleeding and brain swelling may develop after Acoustic Neuroma surgery. If this occurs a subsequent operation may be necessary to reopen the wound to arrest bleeding and allow the brain to expand. This complication can result in paralysis or death.
Infection may occur after surgery and can involve the brain, causing meningitis, an infection of the fluid and tissue surrounding the brain. While this is not common, when this occurs, hospitalization is prolonged. Treatment with high doses of antibiotics is often indicated.