We know that being diagnosed with an acoustic neuroma can be scary, however Drs. Chen and Hillman have managed thousands of patients with this condition and continue to be leaders in the area of acoustic neuroma management and treatment. Both are Board Certified in Otolaryngology, Head and Neck surgery as well as received accreditation in Neurotology. They both have trained fellows, residents and other surgeons in advanced Otology and Neurotology techniques and are equipped to provide you with the best possible care. Their hands on gentle approach to providing you with information, treatment options, and post surgery care is second to none. They will take the time at your visit to answer all of your questions, review your imaging studies, and detail your treatment options. You will leave the office well informed and confident that you are in good hands.
The following is an overview of the Acoustic Tumor.
These tumors are non-malignant fibrous growths that do not spread (metastasize) to other parts of the body. They constitute six to ten percent of all brain tumors.
These growths are located deep inside the skull and are adjacent to vital brain centers. The first signs or symptoms one notices are usually related to ear function and include head noise (tinnitus) and disturbances in hearing and balance. A s the tumors enlarge, they involve other surrounding nerves having to do with more vital functions. Headache may develop as a result of increased pressure on the brain. If allowed to continue over a long period of time, this pressure on the brain is ultimately fatal.
In most cases these tumors grow slowly over a period of years. in others, the rate of growth is more rapid. In some, the symptoms are very minimal and in others, severe multiple symptoms develop rather rapidly.
The patient with an acoustic tumor has a very serious problem and one which involves life or death. For these reasons, many diagnostic procedures are used to be as certain as possible of an accurate diagnosis.
Great care is exerted before, during, and after surgery in these cases in order to preserve life. The preservation of life is the most important objective of surgery in these most difficult cases. A secondary objective of surgery is to preserve for future life as many vital structures as possible. For some, a completely normal life results following surgery. For others, minimum or at times even maximum degrees of physical handicap may persist.
To accomplish the preservation of life with a minimum of future physical disturbance, this surgery with pre and post operative care is performed and assisted by a team. This team includes Drs. Chen or Hillman, our audiologist or nerve monitorist, an internist, an anesthesiologist, a specially trained nurse, and a neurosurgeon.
SIZE OF TUMOR
The larger the tumor, the more pronounced are the symptoms. Accordingly, the larger the tumor, the more serious is the operation for its removal.
The removal of an acoustic tumor, whether large or small, is a major surgical procedure, with possibilities of grave serious complications, including death. The risk involved in the removal of these brain tumors must never be minimized.
For purposes of classification, acoustic tumors are described as small, medium, and large.
Acoustic tumors usually originate from the balance nerve between the inner ear and the brain. they may, however, primarily originate from the hearing nerve. These small tumors are still confined within the bony canal that extends from the inner ear to the brain. Through this canal pass the hearing, balance, and facial nerves and the blood vessels which supply the inner ear.
The operation for removal of a small tumor is performed under general an anesthesia using the operating microscope. If useful hearing is present, the surgical approach is made through an incision in front of and above the ear, which is known as the Middle Fossa Approach, or behind the ear which is known as Retrosigmoid Approach.
The tumor is totally removed in most cases. On rare occasions only partial removal can be accomplished. Every effort is made to preserve the hearing and still remove the tumor. In about 50% of these cases the tumor involves the hearing nerve or the artery leading to the inner ear, which results in a deaf ear post operatively.
MEDIUM SIZED TUMORS
Medium sized tumors are those which have extended from he bony canal into the brain cavity but have not yet produced pressure on the brain itself.
The operating for medium sized tumors is performed under general anesthesia using the operating microscope. The surgical approach is made through an incision behind the ear overlying the mastoid bone. this approach is known as the Translabyrinthine Approach. The mastoid and the inner ear structures are removed to expose the tumor. The tumor is then removed totally. Occasionally, only partial removal is accomplished. The mastoid bone defect is closed with fat from the abdomen.
The Translabyrinthine Approach sacrifices the hearing and balance mechanism of the inner ear. Consequently, the ear is made permanently deaf. Although the balance mechanism has been removed on the operated ear, the balance mechanism of the opposite ear usually provides stabilization for the patient in a relatively short time, one to four months after surgery.
Large tumors are those which extend out of the bony canal into the brain cavity and are sufficiently large to produce pressure on the brain and disturb the vital centers of the brain.
The operation for large sized tumors is performed under general anesthesia using the operating microscope. The surgical approach is through an incision behind the ear overlying the mastoid bone. This approach is known as translabyrinthine-suboccipital approach. The mastoid, inner ear structures, and a portion of the skull are removed to expose the tumor. The tumor is then totally removed unless vital sign changes occur. If there are changes in the blood pressure, pulse rate, or respiration rate the surgery must be terminated before the tumor is totally removed. In this case, a second operation to complete the tumor removal is usually necessary.
The mastoid bone defect is closed with fat taken from the abdomen. In some cases a bone replacement material can be used to fill the defect.
Operation for large acoustic rumors requires extensive removal of bone to properly expose the tumor and control the large blood vessels which obstruct the access to the tumor. For this reason, special vascular studies may be required with any other procedures necessary to diagnose and establish the size of the acoustic tumor.
The hearing and balance mechanism of the involved ear is removed by the surgery. The ear is, therefore, totally deaf. the balance mechanism the opposite ear usually compensates to eliminate unsteadiness in approximately one to four months.
Obviously, it is not possible to list every complication that might occur before, during, or following a surgical procedure. The following discussion of complications is included to indicate some of the complications peculiar to this type of surgery.
In general, the smaller the tumor at the time of surgery, the less chance of complications. If the tumor enlarges, the incidence of complications that may occur becomes increasingly greater.
In small tumors (usually under 1.5 cm or .6 inch), it may be possible to save still present hearing. Monitoring of hearing function during surgery is a technique currently being perfected to assist in this preservation. However, in medium or large tumors (those which protrude from the canal into the brain) the hearing usually has been partially or totally lost, and cannot be restored. This means that the problems locating the direction of sound, hearing a person speaking softly on the deaf side, and understanding speech over a high level of background noise, will continue. For some, A CROS aid will be helpful. A 30 day, money back trial will be allowed.
Ear noises usually remain the same as before surgery. IN a few instances internally produced sounds begin after tumor removal. There are several options available from our audiologists that may help some affected by tinnitus.
In surgery for all sizes of acoustic tumors, it is necessary to remove either part or all of the balance nerve, and in most cases to remove the inner ear balance mechanism. In most cases the balance mechanism has been greatly damaged by the acoustic tumor and for this reason the removal of this mechanism results in an improvement in the patient’s unsteadiness. Occasionally, however, there can be a temporary increase in the balance disturbance. When this occurs, the balance mechanism of the other ear compensates and the unsteadiness usually subsides over a period of one to four months. Some patients may, for as long as several years, notice unsteadiness when they are extremely fatigued.
At times the blood supply to a portion of the brain responsible for balance (cerebellumO is decreased by the tumor or the removal of the tumor. In this case difficulty in coordination in arm and leg movement (ataxia) may result.
Facial Nerve Function
The facial nerve stimulates movement of the muscles of facial expression as well as the muscles which close the eye. This nerve passes through the bony canal that leads from the inner ear to the brain. This nerve is often compressed and distorted by the tumor as it grows within this bony canal. By using the operating microscope, it is often possible to carefully separate the tumor away from this delicate nerve without permanent damage. In many cases, however the nerve is stretched and temporary facial weakness results. This causes a limitation of movement on the operated side of the face. This facial weakness usually clears up in one to three months following surgery, but at times may take up to a year or more.
In approximately 5% of the cases the facial nerve passes through the interior of the tumor, or the tumor may even originate from the facial nerve (facial nerve neuroma). In this case the nerve is sacrificed at the time of surgery. If the nerve is sacrificed, a nerve graft can sometimes be placed in position at the time of the tumor removal. In other cases where the facial nerve has been disturbed, a subsequent operation can be performed to improve the facial movements. In either event, once the facial nerve is disturbed, the facial movements are not totally restored regardless of the method of surgical repair that is instituted.
If it is not certain whether or not the nerve has been totally damaged, facial function is observed for a period of months following surgery. If it becomes certain that the facial nerve function will not recover, a second operation is performed to connect the facial nerve with another nerve in the neck. Either the nerve grafting or the nerve connection (anastomosis) procedure allows partial restoration of the nerve function in six months to one year.
If there has been major damage to the facial nerve, or if grafting or anastomosis has become necessary, it is often advisable to place a gold weight into the upper eyelid to help close the eye and protect it. This procedure is done under local anesthesia by an eye specialist and keeps the eye moistened as well as provides comfort and improved appearance for the patient.
Headache is often present before the removal of an acoustic tumor and it may continue to be a problem following the removal of the acoustic tumor. The usual cause of this is related o the balance mechanism of the inner ear, since it has a great deal to do with the reflex control of the neck muscles. If this is a problem in your case treatment can be instituted to help control this problem
Spinal Fluid Leak
In a small number of cases fluid from around the brain can leak out through the incision or nose. If this occurs it usually is stopped with a spinal drain temporarily for 2 to 3 days. Rarely is re-operation necessary.
As acoustic tumors enlarge they become more and more intertwined with the adjacent brain structures and with the blood vessels that supply the vital brain centers that control respiration, blood pressure, and heart function. Every effort is exerted at the time of surgery to avoid interference with the adjacent brain tissue and with this vital blood supply. If the blood supply is disturbed at the time of the surgery, serious consequences such as a loss of muscle control, paralysis or even death may ensue. In our experience, death occurs very rarely in the removal of small acoustic tumors, in less than 1% in medium or large acoustic tumors.
Postoperative Bleeding and Brain Swelling
Occasionally, bleeding or brain swelling may develop after surgery. If this occurs, a subsequent operation may be necessary to reopen the wound to arrest the bleeding and allow the brain to expand. The complication of postoperative bleeding and brain edema can result in death.
Postoperative infection following acoustic tumor surgery may be a serious complication. Many precautionary measures are taken to prevent infection from developing, including the use of high doses of antibiotics when indicated. Complications such as allergic reactions and suppression of the blood forming tissues can occur due to antibiotic administration. These antibiotic complications are rare but this risk must be taken to treat postoperative infection.
In some cases it is necessary to replace blood that is lost during the surgical procedure. Certain complications can develop due to transfusion, such as reaction of tissue and delayed hepatitis. Such complications are rare, and the advantage of the blood replacement far outweighs the risks involved.
PARTIAL VS TOTAL REMOVAL OF ACOUSTIC TUMOR
Total removal of acoustic tumors, without complications is the goal of management of these tumors
Partial removal of the tumor, regardless of its size, may be necessary if the patient’s responses during surgery indicate disturbance of the vital brain centers that control respiration, blood pressure, or heart function. If signs of vital brain center disturbance develop during surgery, it is sometimes necessary to terminate the operation before the tumor can be totally removed. This will often allow these vital brain center functions to be restored. Once they are disturbed, however, they some times do not recover.
If premature termination of the operation is necessary in the judgement of the operating surgeon, the remaining portion of the tumor may gradually enlarge to again produce symptoms. In this event, a subsequent operation might be necessary. This subsequent operation can often be then accomplished without significant changes in vital signs.
In the event your tumor is partially removed, you will be so informed. Usually the first operation reduces the size of the tumor sufficiently so that it has a chance to separate away from the vital brain centers and it can, therefore, be successfully removed at a later date. In most cases we wait four to six months and then electively operate again for tumor removal.
In other cases, a course of continued observation is restored too. In this instance the tumor will be evaluated from time to time for possible regrowth and accordingly a decision made regarding it removal.
Radiation therapy is an alternative to surgical therapy for acoustic tumors. Targeted, focused beams of radiation are used to stop the tumor growth. The major advantage of radiation therapy is that surgery is not required. The three available forms of radiation are Gamma Knife, X-Knife, and the CyberKnife. The CyberKnife can be delivered in split dosing. For small tumors, the hearing and facial nerve results are similar to surgical treatment. There are a few disadvantages however. Radiation does not remove the tumor, but simply stops its growth. One out of ten tumors will continue to grow and need surgery, which can be more difficult after radiation. Long term results are not yet known either. Finally, there is a small chance that radiation can turn these benign tumors into malignant ones. This risk is low (about 1 in 1000). Because of this, however, we typically reserve radiation treatment for older patients or for those in which an operating would be risky.
Unfortunately, there is no known cure for acoustic tumors except surgical removal. The earlier they are diagnoses and removed, the less likely the possibility of serious complications.
Many patients have unilateral hearing loss, head noise, and balance difficulties. Rarely are these symptoms due to an acoustic tumor. Unfortunately, a very careful check of all patients with these symptoms does not always result in an early diagnosis of acoustic tumors. In some cases the tumor becomes relatively large before a definite diagnosis can be established. The problem must be faced as it exists at the time of diagnosis and acceptance made of whatever risks are necessary to remove these tumors. The risks of surgery are far less than the risk of leaving the tumor untreated.
These above statements are based on our personal experiences in managing a large series of acoustic tumor cases. Should you have any questions pertaining to the problem of your tumor, please discuss them with us.