An acoustic neuroma is a benign tumor that grows on the nerve that connects the inner ear to the brain. It can cause hearing loss, balance problems and ringing in the ears. Radiation therapy, also known as radiosurgery or gamma-knife radiosurgery, is a common treatment for those with small tumors or who aren't up to surgery. Radiosurgery works by precisely targeting radiation beams at the tumor to avoid healthy tissue and stop the tumor from growing. The procedure does not completely remove the tumor and it does carry some risks.
Increasing Symptoms
Radiosurgery works by damaging the cells of the tumor so they eventually die or stop multiplying and the tumor stops growing, according to the International Radiosurgery Support Association. But this occurs gradually over time and so the full effects of radiosurgery, both good and bad, can take months or even years to show up. In fact, the tumor may actually swell a little in the first two years after treatment and actually increase symptoms, according to the Acoustic Neuroma Association. Patients may experience facial numbness or weakness or deafness in the treated ear. Except for the hearing loss, these effects are usually temporary. But most of the time the tumor will slowly shrink over time. About a third of tumors will shrink a year after treatment and after ten years, 90 percent will have decreased in size, according to IRSA.
Hearing Problems
Hearing loss is a possible complication of treatment. It can gradually develop up to two years after treatment but if hearing loss has not occurred at that point, it is unlikely to develop, according to the IRSA. People with smaller tumors are more likely to preserve their hearing. Up to 45 percent of radiosurgery patients experience some hearing loss, according to IRSA. Treatment does not restore hearing once it is lost to the tumor. Hearing loss may also be accompanied by ringing in the ears.
Facial Weakness
Another possible complication of radiosurgery is damage to the nerves that control some of the muscles in the face, which can cause temporary or permanent paralysis of part of the face. This occurs in less than 3 percent of patients who have their radiosurgery treatment done at an experienced center, according to IRSA. Patients may also experience dryness in the eyes and headaches, according to the Acoustic Neuroma Association.
Balance Problems
Many patients feel unsteady on their feet or have episodes of dizziness due to an acoustic neuroma. These symptoms may increase after radiosurgery, according to IRSA, but they are usually temporary and go away after time. Staying active after treatment can help reduce balance difficulties and in some cases therapy is needed to help patients cope, the Acoustic Neuroma Association notes.
Other Risks
There is a small risk that the radiation used during treatment will cause more tumors to grow or make a slow growing tumor more aggressive. According to IRSA, this risk is estimated to be 1 in 1000 patients or less. There is also a risk that the radiosurgery will create scar tissue that causes the tumor to stick to nearby nerves or other structures. This could be a problem if the tumor grows or recurs and surgery is needed to remove it because it can make it harder for the surgeon to safely cut out the tumor. Since radiosurgery does not completely remove the tumor, the patient will needed to get repeated MRIs to make sure that the tumor is not growing or becoming dangerous, according to the Acoustic Neuroma Association.
