Tumor regrowth is possible after treatment by either microsurgery or radiosurgery/radiotherapy. For microsurgery, advanced techniques by experienced medical teams now make the possibility very slight, but it does exist, and therefore a schedule of post-treatment checkups by MRI is recommended. Regrowth is more likely and appears to occur sooner in cases of partial removal. Regrowth following a total surgical removal is not very likely after five years have passed. At the 2007 International Conference on Vestibular Schwannoma in Barcelona, Spain, the incidence of tumor regrowth following microsurgery, with variation depending on level of experience, was quoted as 0.3 – 3%.
At the same International Conference, the incidence of tumor regrowth following radiosurgery was quoted as 2 – 6%. For Gamma Knife radiosurgery, a 1998 University of Virginia report on long-term outcomes showed tumor regrowth in 4 patients out of 162 (2.5%) three years after treatment. The failed patients underwent resection, which was described by the operating surgeons as no different in degree of difficulty from that for non-irradiated tumors in three cases and more difficult in one. In 2005, Komaki City Hospital in Japan reported on 301 patients treated by Gamma Knife during 1991-1998. The tumor control rate at median follow-up of 7.8 years was 93%. A number of the tumors were treated at 13 Gy or less. [Gy is a unit of absorbed radiation] Twenty-two patients (7%) experienced treatment failure, which “usually occurred within 3 years.” In 2007, the University of Pittsburgh Gamma Knife Center reported on 161 patients treated during 1987-2003 (dosage range of 12-13 Gy). For 145 evaluable patients, the tumor control rate at median follow-up of 24 months was 99.3%. One patient (0.01%) failed radiosurgery and underwent a resection. An earlier Pittsburgh study in 2003 reported a tumor control rate of 93.7% and a failed radiosurgery rate of 5%. This was for 13 out of 285 patients, 1987-1992, with median follow-up of 10 years.
Comparable long-term data has yet to be presented for tumor regrowth following fractionated radiotherapy (FSR). Some FSR studies have reported tumor control rates as high or higher than Gamma Knife or Linac radiosurgery; however, not all studies have been consistent for reporting on length of follow-ups, size of tumors involved and radiation dosages employed. Data on outcomes needs to be presented in ways that facilitate helpful comparisons between types of radiation treatments.
Pretreatment counseling should include the information that tumors often increase in size/swell following radiation treatment. A Mayo Clinic study (2006) reported that 30 out of 208 patients (14%) had tumors that enlarged by at least 2mm following radiosurgery. The median time to enlargement was nine months. Some of the tumors remained larger, and some regressed. Four of the patients showed progressive tumor enlargement on serial imaging and underwent additional treatment (resection, 3; radiosurgery, 1). The study concluded: “Tumor expansion after radiosurgery rarely denotes a failed procedure. . . Additional tumor treatment should be reserved only for patients who demonstrate progressive tumor enlargement on serial imaging (2% in this series).” There is little available data regarding a second radiosurgery for a failed radiosurgery. The Pittsburgh and New England Gamma Knife centers have reported some success with the approach; however, questions have been asked about the efficacy of reradiating a tumor that has perhaps already demonstrated sufficiently that it is not radioresponsive.
- See also “Update from the 5th International Conference on Vestibular Schwannoma,” by Dr. Richard Wiet, ANA Notes, Issue 103 (September 2007).
- See also, ANA Notes, Issue 62 (May 1997) for articles on tumor regrowth by Dr.Robert Wilkins (Duke University), “Regrowth of Acoustic Neuroma,” and Dr. Donald Kamerer (University of Pittsburgh), “Recurrence of Acoustic Tumors.”
- See also “Acoustic Neuromas that Enlarge after Gamma Knife Radiosurgery,” ANA/NJ Newsletter (September 2008) - click here .
Preservation of Hearing
Except for the smallest tumors, preservation of hearing in the affected ear at preoperative levels seems an elusive goal when treating acoustic neuroma. Hearing rarely improves after treatment. For microsurgery patients, preservation of hearing is not likely in removals of tumors exceeding 2.0 cm in diameter. One 1997 study of 60 patients who were candidates for “hearing preservation surgery” showed 50% success for tumors less than 1.5cm and 16% success for tumors that were larger. Another 1997 study of 179 patients showed 48% success for tumors less than 2.0cm, 25% success for medium tumors 2.0 to 3.9cm, and 0% for large tumors 4.0cm or greater. A 1997 House Ear Institute study reported 68% success using the middle fossa approach in 151 cases of tumors 0.5 to 2.5cm (mean 1.2cm). For Gamma Knife radiosurgery, a University of Virginia report in 2000 showed that 58% of 36 patients with useful hearing still retained their hearing four years after treatment. Hearing preservation was best with radiation doses of not more than 13 Gy for tumors less than 1.0cm. All patients with tumors 3.0cm and above lost hearing in the affected ear. As radiation dosages have been lowered to 12-13 Gy, there has been great improvement in hearing preservation rates. In 2004 the Gamma Knife Center at the University of Pittsburgh, for example, reported a 70-73% hearing preservation rate for 313 patients treated at 12-13 Gy. The International RadioSurgery Association’s Braintalk (vol. 9, 2004) has compared reported preservation rates: Gamma Knife and Linac radiosurgery (SRS), 70-71%; Linac fractionated radiotherapy (FSR), 47-61%; Proton beam radiosurgery, 33%; fractionated Proton beam, 31%. More recent experiences (2002-07) with FSR and low radiation dosages at Thomas Jefferson University yielded an impressive hearing preservation rate of around 80%. It will be necessary to continue to assess the effect of low dose radiation treatments on tumor growth control.
- See also "FSR Outcomes Stronger for Hearing Preservation,” by Dr. David Andrews (Thomas Jefferson University), ANA Notes, Issue 106 (June 2008).
- See also "Hearing Loss Rehabilitation for Acoustic Neuroma Patients," by Drs. Ravi Samy & Julie Honaker, ANA Notes, Issue 102 (June 2007)
Headaches as a symptom of acoustic neuroma are uncommon but may occur with medium or large tumors. Headaches following microsurgical removal of an acoustic neuroma have been unfortunately quite common and can be severe, persistent, difficult to treat and sometimes debilitating. The 1998 ANA Survey showed that 78% of 692 patients who reported headaches after surgery experienced them in a severe form, and for 64% the headaches persisted for more than three years. The 2008 ANA Survey’s data on 466 surgery patients does not allow for comparisons, but would seem to indicate that, while continuing, the headache problem has somewhat moderated.
Headaches immediately following acoustic neuroma surgery should be anticipated, but typically respond well to medication (Prednisone, Ibuprofen) and resolve within several weeks. Maintaining hydration is important. For relief from seemingly intractable headaches that persist for months or even years, some possible causes to discuss with professionals and investigate in the literature are: (a) over-medication with painkillers leading to ‘rebound’ headaches (b) headache ‘triggers’ such as caffeine, red wine, nuts, stress, tiredness, diet pills (c) occipital nerve damage or entrapment (d) craniectomy during surgery instead of cranioplasty. Some corrective measures to consider are: (a) preventive medication, Verapamil (b) muscle relaxants and neck muscle therapy (c) cranioplasty (d) alternative treatments such as massage therapy, acupuncture (e) stress reduction (f) keeping a headache diary. Achieving headache control can be difficult and is best done under the supervision of a neurologist experienced in headache management. As advised in ANA’s booklet Headache Following Acoustic Neuroma Surgery (2004): “In the most treatment-resistant cases, it may be necessary to treat post acoustic surgery headaches in a multidisciplinary pain center.”
- See also “Headache Associated with Acoustic Neuroma Treatment,” by Dr. John Ryzenman (Ohio Ear Institute), ANA Notes, Issue 101 (March 2007).
- See also “The Headache Problem Revisited” in the ANA/NJ Newsletter (April 2006) - click here.
Common complaints by AN patients include: instability when turning quickly, difficulty walking in the dark and on uneven surfaces, problems with changes in light intensity, fatigue. An excellent series of articles in ANA Notes (see below) explains: “Essentially everyone who has been treated for an acoustic neuroma experiences difficulty with balance to some degree. For some, this instability may be mild. . . For others, there may be difficulty returning to work, or even performing regular daily activities. . . .” Following treatment of the AN, the brain needs time to adjust to the loss of function of its balance system on the affected side. This period of adjustment will be brief if the tumor has been surgically removed, whereas after radiation treatment, change occurs more slowly. “A potential cause of persistent unsteadiness after radiation therapy is intermittent malfunctioning of the remaining active balance fibers within the tumor.” Patients who do not recover balance spontaneously or within a reasonable period of time should seek rehabilitation by a therapist skilled in the treatment of balance and vestibular disorders. A customized program of balance retraining is best.
- See also “Improving Balance Following Treatment for Acoustic Neuroma,” Parts I and II, by Dr. Glenn Johnson & Dawna Pidgeon, PT (Dartmouth-Hitchcock Medical Center) ANA Notes, Issues 72 & 73 (December 1999, March 2000).
- See also ANA’s booklet, Improving Balance following Treatment for Acoustic Neuroma (2004).
Depression & Memory
Depression can be set off by a traumatic situation or stressful time; undergoing testing and a long surgery under general anesthesia for a brain tumor is no picnic. There are other life-changing side effects of acoustic neuroma surgery, such as facial problems, hearing loss, tinnitus, imbalance, head pain, fatigue. All of which helps to explain why the post-surgery depression rate has been reported as higher for AN patients than for other surgeries. Depression disorders can be helped by participation in a support group, individual counseling and appropriate anti-depressant medications. Guidance by a doctor specializing in depression disorders is advisable.
Problems especially with short-term/working memory can result after a major surgery. “The true art of memory is the art of attention,” and clearly, the acoustic neuroma experience comes loaded with potential ‘attention-busters.’ There can be problems, at least temporarily, with listening, concentration, remembering, learning new things. A possible anatomic cause of memory difficulty is retraction of the temporal lobe of the brain during surgery, which can put stress on the temporal lobe’s memory circuitry. Then too, it has been theorized that a memory-important area of the brainstem, the locus ceruleus, may be disturbed by the size and/or treatment of an acoustic neuroma.
- See also “Cognitive Changes and Depression with Acoustic Neuroma,” by Dr.Elisabeth Kunkel (Thomas Jefferson University), ANA Notes, Issue 107 (September 2008).
- See also “Acoustic Neuroma & Memory Problems,” ANA/NJ Newsletter (September 2007 - click here and April 2008 - click here).
Tinnitus is a common symptom of the hearing disorder associated with acoustic neuroma. Treatment of the acoustic neuroma by either microsurgery or radiation should not be expected to cure the tinnitus. A 1998 House Ear Clinic survey of 500 patients showed that about 40% reported their tinnitus improved after surgery, 50% said it was the same, and 10% said it was worse. For 1,348 patients, the ANA 1998 Survey reported tinnitus after surgery ranging from 46% of patients with small tumors to 37% for patients with large tumors. For the ANA 2008 Survey, 60-70% of patients indicated that their tinnitus continued after treatment. The Gamma Knife Center at the University of Virginia has reported that 26 of 153 radiosurgery patients (1989-99) had tinnitus at treatment; in 3 cases the tinnitus improved while for the rest it was unchanged. There is as yet no definitive cure for tinnitus, but tinnitus sufferers have found varying levels of relief with Tinnitus Retraining Therapy (TRT) and with the more recent Neuromonics. These are treatments that take advantage of the brain’s remarkable plasticity for retraining to ignore the tinnitus.
- See also “Tinnitus and Acoustic Neuroma,” by Dr. John House (House Ear Clinic), ANA Notes, Issue 86 (June 2003).
Facial Nerve & Eye Problems
Especially for large tumors, facial weakness and eye problems continue as possible side effects for treatments of acoustic neuromas. The 2008 ANASurvey reports that, for 1,188 microsurgery patients, 24% (277) underwent subsequent treatment to correct for facial weakness, and 35% (421) required some form of eyelid surgery. For comparison, of 271 radiosurgery patients, 9% had subsequent treatment to correct facial weakness, and 9% required some form of eyelid surgery. The percentages were similarly low for FSR patients. The various types of facial nerve and eye problems that can occur, along with associated reanimation procedures and neuro-muscular retraining techniques, are described and diagramed in ANA's booklets for The Facial Nerve and Acoustic Neuroma (2002) and Eye Care after Acoustic Neuroma Surgery (2005).
Cerebrospinal Fluid (CSF) Leakage
The basic article on CSF by Dr. Albert Rhoton (University of Florida) reported that drainage of cerebrospinal fluid from the nose following acoustic neuroma surgery might occur in as many as one in eight operations, 13%. “A leak can occur because acoustic neuromas extend into the cerebrospinal fluid-filled spaces under the brain, which are opened at the time of tumor removal.” The majority of cases occur in the first days after surgery and usually resolve after a few days. The 2008 ANA Survey reported CSF leakage in 211 of 1,188 surgery cases (18%); one case was reported for radiosurgery; no cases were reported for FSR.
- See also “Drainage of Cerebrospinal Fluid from the Nose after Surgery for Acoustic Neuroma,” by Dr. Albert Rhoton, ANA Notes, Issue 92 (December 2004)
Simply defined, fatigue is the condition of being very tired because of physical or mental exertion. Prolonged or chronic fatigue, on the other hand, is a persistent tiredness and lack of energy not related to activity. In fact, one of its main characteristics is reduced motivation and capacity for any form of physical or mental activity. Probably the majority of AN patients who undergo treatment experience this more serious type of fatigue for only a relatively brief period. That is, for a time there is a dramatic decrease in energy because of the emotional impact of diagnosis and testing and/or the trauma of anesthesia and a long surgery, but usually within 3-4 months the patient bounces back and resumes normal activity. Some patients, however, may continue to feel a profound tiredness for many months or even years. Such prolonged fatigue can seriously affect emotional well-being, social ability, concentration and quality of life in general. Patients are advised to seek professional help. Acoustic neuroma patients need to keep in mind that, as life experiences accumulate, fatigue-causing conditions not related to AN may occur to complicate and confuse perceptions. Prolonged fatigue may also be caused by diabetes, hypothyroidism, fibromyalgia, shortness of breath, sleep apnea, stress, depression, iron deficiency anemia, prescription drugs, or even a special condition being defined as chronic fatigue syndrome (CFS).