Acoustic Neuroma

For further information and support, please contact the Acoustic Neuroma Association of New Zealand, a mutual-aid group, organised and administered by ex-patients and their families.

Postal Address - P O Box 222, Taumarunui
Phone - 07 896 7452
Email - info@acousticneuroma.org.nz or acousticneuromaassnofnewzealand@xtra.co.nz



What is it?

A vestibular schwannoma, often called an acoustic neuroma, is a benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (8th cranial nerve). A type of schwannoma, this tumor arises from the Schwann cells responsible for the myelin sheath that helps keep peripheral nerves insulated. Approximately 3,000 cases are diagnosed each year in the United States with a prevalence of about 1 in 100,000 worldwide. It comprises 5–10% of all intracranial neoplasms in adults. Incidence peaks in the fifth and sixth decades and both sexes are affected equally.

Signs and symptoms
Acoustic neuroma usually develops gradually over a period of years, roughly 1–2 mm each year; most often, it may not come up with any obvious symptoms in the earlier stages. As a result, many patients with this tumor often fail to recognize any possible symptoms in the initial periods. They repeatedly consider the most obvious initial symptom like decreased hearing in the ears as normal changes due to aging. The earliest symptoms of acoustic neuromas include ipsilateral sensorineural hearing loss/deafness, disturbed sense of balance and altered gait, vertigo with associated nausea and vomiting, and pressure in the ear, all of which can be attributed to the disruption of normal vestibulocochlear nerve function. Additionally more than 80% of patients have reported tinnitus (most often a unilateral high-pitched ringing, sometimes a machinery-like roaring or hissing sound, like a steam kettle).

Large tumors that compress the adjacent brainstem may affect other local cranial nerves. Paradoxically, the 7th cranial nerves are rarely involved pre-operatively; involvement of the trigeminal nerve (CN V) may lead to loss of sensation in the involved side's face and mouth. The glossopharyngeal and vagus nerves are uncommonly involved, but their involvement may lead to altered gag or swallowing reflexes.

Larger tumors may lead to increased intracranial pressure, with its associated symptoms such as headache, vomiting, and altered consciousness.



Hearing loss

Patients with a severe or profound unilateral hearing loss following the removal of an acoustic neuroma tumour are significantly disabled in a number of situations such as hearing sounds from the deaf side, hearing in the presence of background noise (both in quiet and noisy surroundings) and localising sounds.

The perceived hearing handicap may even be greater in unilateral losses than in bilateral. It has also been reported that patients with unilateral hearing loss experience difficulties in group discussions and dynamic listening situations where there is limited possibility to compensate for the handicap by changing listening position.

It is recommended that the hearing difficulties after tumour removal should be thoroughly examined with each patient and rehabilitative options discussed.













Pathogenesis

Acoustic neuromas may occur idiopathically (meaning the cause is unknown), or in some cases occur as part of von Recklinghausen neurofibromatosis, in which case the neuroma may take on one of two forms.

In Neurofibromatosis type I, a schwannoma may sporadically involve the 8th nerve, usually in adult life, but may involve any other cranial nerve or the spinal root. Bilateral acoustic neuromas are rare in this type.
In Neurofibromatosis type II, bilateral acoustic neuromas are the hallmark and typically present before the age of 21. These tumors tend to involve the entire extent of the nerve and show a strong autosomal dominant inheritance. Incidence is about 5 to 10%.
The usual tumor in the adult presents as a solitary tumor, originating in the nerve. It usually arises from the vestibular portion of the 8th nerve, just within the internal auditory canal. As the tumor grows, it usually extends into the posterior fossa to occupy the angle between the cerebellum and the pons (cerebellopontine angle). Because of its position, it may also compress the 5th, 7th, and less often, the 9th and 10th cranial nerves. Later, it may compress the pons and lateral medulla, causing obstruction of the cerebrospinal fluid and increased intracranial pressure.

Schwannomas can occur in relation to other cranial nerves or spinal nerve roots, resulting in radiculopathy or spinal cord compression. Trigeminal neuromas are the second most common form of schwannomas involving cranial nerves. Schwannomas of other cranial nerves are very rare.

Diagnosis

Contrast-enhanced CT will detect almost all acoustic neuromas that are greater than 2.0 cm in diameter and project further than 1.5 cm into the cerebellopontine angle. Those tumors that are smaller may be detected by MRI with gadolinium enhancement. Audiology and vestibular tests should be concurrently evaluated using air conduction and bone conduction threshold testing to assess for sensorineural versus conduction hearing loss.


[Image - Acoustic neuroma on the right with a size of 20x22x25mm]

Treatment

Indicated treatments for acoustic neuroma include surgical removal and radiotherapy. About 25% of all acoustic neuromas are treated with medical management consisting of a periodic monitoring of the patient's neurological status, serial imaging studies, and the use of hearing aids when appropriate.

Conservative treatment

Because these neuromata grow so slowly, a physician may opt for conservative treatment beginning with an observation period. In such a case, the tumor is monitored by annual MRI to monitor growth. This route is common among patients over 70 years old. Records suggest that about 45% of acoustic neuromata do not grow detectably over the 3–5 years of observation. In rare cases, acoustical neuromata have been known to shrink spontaneously. Often people with acoustic neuromata die of other causes before the neuroma becomes life-threatening. This is especially true of elderly people possessing a small neuroma.

Since the growth rate of an acoustic neuroma rarely accelerates, annual observation is sufficient. Acoustic neuromata may cause either gradual or—less commonly—sudden hearing loss and tinnitus.


Surgery

Removal of acoustic neuromas may be performed using several approaches. Each approach has its advantages and disadvantages. Microsurgery for acoustic neuroma is the only technique that removes the tumor. Radiation treatment (discussed in another section) does not remove the tumor, but has the potential to slow or stop its growth. Surgery is the only treatment that will definitively treat balance symptoms associated with tumor growth, as the vestibular nerves are removed at surgery.

Surgery cannot repair damage that has already occurred to the facial or hearing nerves. Even after surgery, there is a small chance that the neuroma will grow back and follow-up MRI scans are necessary.

Choice of surgical approach is based on the patient's age, medical condition, size of tumor, and preoperative hearing thresholds and speech discrimination, as well as other tests such as electronystagmography, imaging, and auditory brainstem response testing. The patient's and surgeon's preferences also play a significant role.

During removal of the tumor, the tumor along with the superior and inferior vestibular nerves are removed. This results in an acute loss of vestibular input to the brain from the operated side. However, vestibular function improves rapidly due to compensation by the other ear and other balance mechanisms.

Surgery carries risk to the facial nerve which may therefore be monitored during the procedure. Best results (normal or near normal facial function) are more likely with small acoustic neuromas.

Three surgical approaches are commonly used. The first is the translabyrinthine approach, which destroys hearing in the affected ear. Thus, it is often employed in patients who already have poor speech discrimination in the affected ear. Any size tumor may be removed with this approach. There is no brain retraction with this approach, so it is often considered the safest route to remove the tumor. In patients with neurofibromatosis type 2 who undergo auditory brainstem implantation, this technique is used as it provides the most direct path of access to the lateral recess and cochlear nucleus, where the device is placed.

The two other approaches (suboccipital retrosigmoid and middle fossa) are hearing preservation approaches, which have a chance of preserving some or all of the hearing in the affected ear. Neurosurgeons often prefer the retrosigmoid approach, as they are frequently more familiar with it from training.

The middle fossa approach is used for tumors typically less than 2 cm in greatest dimension, where hearing conservation is to be attempted. This approach has the advantage over the retrosigmoid approach in its direct access to the lateral end of the internal auditory canal. Multiple reports have shown that the retrosigmoid approach cannot reach the lateral end of the internal auditory canal without violating the posterior semicircular canal, and hence destroying the hearing.
A less common approach is minimally invasive endoscopic surgery. This approach is available in specialized centers.

Acoustic neuroma surgery is highly technically demanding. It may be performed by neurosurgeons or otolaryngologists, alone or together.


Radiation therapy

Radiation therapy is done in a variety of ways, but mainly by four methods: CyberKnife, gamma knife radiosurgery, fractionated stereotactic radiotherapy, with a linear accelerator (linac), or proton therapy. In the gamma knife approach, 201 beams of gamma radiation are focused on the tumor in a single session. The damage to the tumor at the convergence point may cause it to stop growing but usually does not cause it to shrink in the long term. It may cause short-term shrinkage due to necrosis in the tumor. The damage may be to the tumor cells and/or to the tumor vasculature.
It is not clear what percentage of tumors are controlled by this method for long periods. In earlier times when higher radiation doses were used, the failure rate was about 12% (which then required surgery). Most surgeons feel that these tumors are much more difficult to remove after radiation treatment. Radiation does not remove the tumor, and when irradiated tumors are surgically removed, it is often found that they have growing tumor cells in them.

Two risks of radiation treatment are carcinogenic progression of the acoustic neuroma (conversion from benign to malignant) or induction of other tumors (such as glioblastoma) in the nearby irradiated brain tissue. The incidence of these events appears to be low, and it is often said to be one in one thousand or less (however, the incidence is markedly higher in patients with neurofibromatosis Type 2). This calculation is done by dividing the number of obvious cases of tumorigenic progression or secondary tumor reported in the medical literature by the estimated number of gamma knife procedures done in the world to date.

Due to the possibility of regrowth and the possibility of tumorigenic progression or secondary tumors, it is essential that radiation treatments for acoustic neuromas be followed by yearly MRI for the rest of the patient's life. Long-term secondary effects (for instance cognitive effects) on a scale of 10–20 years are not yet established for gamma knife surgery.
Fractionated stereotactic therapy involves a beam of ionizing radiation focused on the tumor from a moving gantry. The beam is wider and less accurate than that of the gamma knife. The total dose is also much higher than that used in gamma knife radiosurgery, but the fractionation of the dose (done on many different days) spares normal tissue. This method has not been done on as many patients as gamma knife procedures and there have not been as many years of follow-up study. This means that the tumor control by this method is not yet established, and the incidence of secondary effects of the radiation are not yet known. There are a number of variations on the linac machine, which can confuse patients. The best known are the "Peacock" which is essentially a modified collimator, and the Cyberknife which uses a miniature linac machine attached to a robot arm which is guided using x-ray imaging to check the position of the patient between each treatment shot.

A proton therapy machine uses a beam of protons to kill the tumour and a cyclotron is used to generate the beam. This is preferable to the x-rays used by the linac and gamma knife machines as the protons can be stopped before they exit the tumor, thus reducing damage to normal tissue.



International Organisations

Acoustic Neuroma Association (ANA) 
The Acoustic Neuroma Association (ANA) is a patient-focused organization that provides information and support to those affected by acoustic neuroma. An acoustic neuroma, also called a vestibular schwannoma, is a slow-growing, benign tumor that develops on the eighth cranial nerve: early symptoms include hearing loss, balance problems, and tinnitus. ANA publishes a quarterly newsletter and other consumer information, organizes local support groups, promotes research, and maintains an interactive website. Also holds a national symposium; contact ANA for date and location.

Address: 600 Peachtree Parkway, Suite 108, Cumming, GA,  30041
Phone: (770) 205-8211
Email: info@anausa.org


American Academy of Otolaryngology--Head and Neck Surgery (AAO-HNS) 
The nonprofit American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS) strives to unite, serve, and represent the interests of ear, nose, and throat specialists and their patients to the public, government, other medical specialists, and related organizations. AAO-HNS provides leaflets and geographic lists of physicians to the public at no charge. Holds annual meeting; contact AAO-HNS for date and location. AAO-HNS provides a professional bulletin, journal, directory, books, and other materials. Professional/consumer publications are available online and in print, with some in Spanish.

Address: 1650 Diagonal Road, Alexandria, VA, 22314-2857
Phone (703) 836-4444
Email: webmaster@entnet.org
 

American Neurotology Society (ANS) 
The American Neurotology Society (ANS) is composed of physicians and audiologists devoted to the fields of neurotology and otology. The purpose of ANS is to exchange and disseminate information about the physiology, pathology, and clinical management of the sensorineural systems of audition and equilibrium, and to stimulate education and basic and clinical research relating to these systems. Holds two scientific meetings per year, which are open to anyone in the health sciences and particularly to individuals with major interest areas in hearing and balance. For meeting dates and locations, contact the ANS administrative office.

Address: Administrative Office, 1980 Warson Road, Springfield, IL, 62704
Phone (217) 638-0801
Email: neurotology65@yahoo.com


American Otological Society (AOS) 
The American Otological Society (AOS) is a professional organization that works to advance and promote medical and surgical otology/neurotology, including the rehabilitation of individuals with hearing and balance disorders, and to encourage, promote, and sponsor research in otology/neurotology, lateral skull base surgery, and related disciplines. The educational mission of AOS is to foster dialogue and share information on advances in the understanding and management of otological and neurotologic disorders. Holds annual meeting for members; visit the AOS website for date and location. AOS also publishes peer-reviewed papers and discussions presented during the scientific program of its meeting as well as proceedings of its business meetings.

Address: Administrative Office, 1980 Warson Rd, Springfield, IL, 62704
Phone (217) 638-0801
Email: administrator@americanotologicalsociety.org


American Tinnitus Association (ATA) 
The American Tinnitus Association (ATA) exists to cure tinnitus by developing resources that advance tinnitus research. Founded in 1971, ATA has raised and allocated millions of dollars toward medical research projects focused on a cure for tinnitus. ATA also advocates for effective public policies that support its mission. ATA publishes a triannual magazine in April, August, and December. The magazine includes detailed articles on current research, treatment, and other information for those living with tinnitus and others interested in staying current in this field. Articles from prior issues are available on the ATA website. A consumer directory, fact sheets, and other publications for professionals and consumers also are available online and in print.

Address: P.O. Box 5, Portland, OR,  97207-0005
Phone (503) 248-9985 or 800-634-8978
Email: jennifer@ata.org, or mike@ata.org


Association of Late-Deafened Adults (ALDA) 
The Association of Late-Deafened Adults (ALDA) serves as a resource center providing information and referrals, self-help, and support groups for people deafened as adults. ALDA works to increase public awareness of the special needs of deafened adults. Holds annual conference; contact ALDA for date and location. A professional/consumer directory, proceedings of conventions, and fact sheets are available.

Address: 8038 Macintosh Lane, Rockford, IL, 61107
Phone (815) 332-1515
Email: info@alda.org or president@alda.org


Advocure NF2, Inc. 
Neurofibromatosis Type II (NF2) is a rare, genetic disease that causes tumors to grow throughout the brain and spinal cord, threatening hearing, vision, mobility, and even basic life functions such as swallowing. Advocure NF2, Inc., is a 501(c)(3) public charity and liaison group that advocates for the NF2 Crew (an online-based support community for patients and others) and the NF2 international community. Advocure NF2, Inc., monitors research and drug developments worldwide and works to expedite systemic therapy that may treat and possibly even cure NF2. Its website offers information on understanding and living with NF2, research, and other resources. A quarterly newsletter is available online.

Address: P.O. Box 4118, Clearwater, FL, 33758-4118
Email: contact@advocurenf2.org


Genetic Alliance 
Genetic Alliance improves health through the authentic engagement of communities and individuals. The organization is committed to transforming health through genetics and promoting an environment of openness centered on the health of individuals, families, and communities. Genetic Alliance’s network includes disease-specific advocacy organizations, universities, private companies, government agencies, and public policy organizations.

Address: 4301 Connecticut Avenue, NW, Suite 404, Washington, DC, 20008-2369
Voice: (202) 966-5557
Email: info@geneticalliance.org


House Research Institute 
The House Research Institute (formerly called the House Ear Institute) is a private, nonprofit 501(c)(3) organization dedicated to advancing hearing science through research and education to improve quality of life. Scientists are exploring the developing ear and ear diseases at the cellular and molecular level as well as investigating the complex ear-brain interaction. They also are working to improve hearing aids and auditory implants, clinical treatments, and intervention methods. Professional/consumer brochures, books, and audiovisuals are available.

Address: 2100 West Third Street, Los Angeles, CA, 90057
Phone (213) 483-4431
Email: webmaster@hei.org or kholguin@hei.org


The Hyperacusis Network 
The Hyperacusis Network is an international support group established to care for individuals with a decreased sound tolerance (DST). The network helps educate individuals, families, and the medical community and families about this rare auditory disorder by explaining treatment options, sharing ways to cope, and reporting on current ongoing research. In addition, the network provides a listing of clinicians worldwide who are specifically trained to diagnose and treat hyperacusis. A message board is provided so individuals can share their experiences. The network also offers hearing protection products designed specifically for hyperacusis. Fact sheets, brochures/pamphlets, online publications and resources are available through our website. Membership is free.

Address: 4417 Anapaula Lane, Green Bay, WI, 54311
Phone (920) 866-3377
Email: earhelp@yahoo.com


Hearing Health Foundation 
Hearing Health Foundation is the largest private funder of hearing research, with a mission to prevent and cure hearing loss through groundbreaking research. Since 1958, Hearing Health Foundation has given away millions of dollars to hearing and balance research, including work that led to cochlear implant technology and now through the Hearing Restoration Project is working on a cure for hearing loss. Hearing Health Foundation also publishes Hearing Health magazine, a free consumer resource on hearing loss and related technology, research, and products. To learn more, subscribe to our magazine, or support this work, visit www.hhf.org. 

Address: 363 Seventh Avenue, 10th Floor, New York, NY, 10001-3904
Phone (212) 257-6140
Email: info@hhf.org


National Institute on Deafness and Other Communication Disorders (NIDCD) 
The National Institute on Deafness and Other Communication Disorders (NIDCD), one of the National Institutes of Health, supports and conducts research and research training on the normal and disordered processes of hearing, balance, taste, smell, voice, speech, and language. The NIDCD develops health information based on scientific discovery and disseminates it to the public. In October 2008, the NIDCD launched It's a Noisy Planet. Protect Their Hearing (www.noisyplanet.nidcd.nih.gov). This national campaign is designed to increase awareness among parents of youth ages 8 to 12 about the causes and prevention of noise-induced hearing loss. The NIDCD provides a toll-free telephone service through its information clearinghouse. Fact sheets, brochures, teaching curricula, and reports are available, with many in Spanish.

Address: Office of Health Communication and Public Liaison, 31 Center Drive, MSC 2320, Bethesda, MD,  20892-2320
Phone (301) 496-7243
Email: nidcdinfo@nidcd.nih.gov


National Institute on Deafness and Other Communication Disorders (NIDCD) Information Clearinghouse 
The National Institute on Deafness and Other Communication Disorders (NIDCD) Information Clearinghouse, a service of NIDCD, is a national resource center for health information on hearing, balance, smell, taste, voice, speech, and language for health professionals, patients, and the public.

Address: 1 Communication Avenue, Bethesda, MD, 20892-3456
Email: nidcdinfo@nidcd.nih.gov
http://www.nidcd.nih.gov 


National Organization for Hearing Research Foundation (NOHR) 
The National Organization for Hearing Research Foundation (NOHR) is a 501(c)(3) public charity whose primary objective is to fund research into the prevention, causes, treatments, and cures for hearing loss and deafness. NOHR funds grant proposals that target innovative auditory projects; proposal submissions are reviewed by members of NOHR’s Scientific Review Committee. The most important review criteria for research proposals are scientific value and potential to yield significant new insights in the field of auditory science. Regeneration of sensory hair cells of the inner ear is a research funding priority, and examinations by other scientific disciplines are encouraged. Grant application information is available upon request.

Address: P.O. Box 421, Narberth, PA, 19072
Phone (610) 664-3135
Email: smsnohr@att.net


Neurofibromatosis Network 
Neurofibromatosis, Inc., (NF, Inc.) is a national nonprofit organization dedicated to all people affected by neurofibromatosis (NF) and other related disorders. NF, Inc., distributes materials on NF1 and NF2; promotes national, state, and local community involvement; supports research; has a governing board with NF2 representation; and provides real-time captioning at meetings. A toll-free helpline and website provide access to peer counseling and information 24 hours a day. A professional directory and professional/consumer publications are available.

Address: 213 Wheaton Avenue, Wheaton, IL, 60187
Phone (630) 510-1115
Email: admin@nfnetwork.org


St. Joseph Institute for the Deaf (SJI) 
St. Joseph Institute for the Deaf (SJI) is committed to the spiritual and emotional growth and personal development of hearing-impaired children and young adults. SJI teaches children with hearing loss to hear, speak, and read from birth to eighth grade, regardless of race, religion, gender, or finances. Programs include early intervention; toddler, preschool, and kindergarten through eighth-grade classes; I-Hear teletherapy services; evaluations; local district partnerships; and mainstream consultancy. SJI has an onsite audiology clinic in Chesterfield, Mo.

Address: 1809 Clarkson Road, Chesterfield, MO, 63017
Phone (636) 532-3211
Fax: (636) 532-4560
Email: info@sjid.org


Vestibular Disorders Association (VEDA) 
The Vestibular Disorders Association (VEDA) is a nonprofit organization that provides information, support, and advocacy to people with vestibular disorders and the health professionals who treat them. Such disorders include labyrinthitis, benign paroxysmal positional vertigo (BPPV), Ménière’s disease, Mal de Debarquement, ototoxicity, and perilymph fistula. Frequently reported symptoms of these disorders are dizziness, unsteadiness or imbalance, vertigo, nausea, hearing loss, visual disturbances, and tinnitus. A provider directory of health care specialists, a support group directory, resource library, and more are available on our website. Membership benefits include a quarterly newsletter and access to our member support network. 

Address: 5108 NE 15th Avenue, Portland, OR, 97211
Phone (503) 229-7705
Email: info@vestibular.org
http://www.vestibular.org 


Virginia Merrill Bloedel Hearing Research Center (VMBHRC) 
The Virginia Merrill Bloedel Hearing Research Center (VMBHRC) at the University of Washington conducts interdisciplinary research on hearing, hearing loss, and related communication disorders. Through its diverse programs that foster national and international collaboration between top experts in the field, the center advances the fight against deafness and disequilibrium on the fronts of protection, intervention, and regeneration. The center provides invaluable support to patients, the scientific community, and the general public. 

Address: University of Washington, Box 357923, Seattle, WA,  98195-7923
Phone (206) 685-2962 or (206) 616-4105
Email: bloedel@uw.edu


National Institute on Deafness and Other Communication Disorders
31 Center Drive, MSC 2320, Bethesda, MD USA 20892-2320 
E-mail: nidcdinfo@nidcd.nih.gov 

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