Tuesday, January 18, 2011

Gamma Knife for Acoustic Neuroma


                                                                                         Email:  neuro@braintumors.in

Saturday, January 1, 2011

Surgical therapy for Acoustic Neuroma

Surgery for acoustic neuromas has been performed since the early 1900's. The initial successes were few and far between by the early pioneering neurosurgeons who treated this problem. The past twenty years have witnessed an astounding improvement in our abilities to successfully deal with these tumors while preserving the neurological function of the patient.

In contemporary surgical treatment of these tumors, the vast majority of patients lead a normal life following their surgery. The two main concerns that patients typically have is preservation of facial nerve function and of hearing. The facial nerve exits the brain stem and is anatomically in a position adjacent to the vestibulocochlear nerve. The anatomical relationships of the nerves to the structures of the inner ear and the brain stem can be seen in the section on anatomy. Preservation of facial nerve function is extremely important because of its cosmetic implications. Normal movement of the face on each side is controlled by the facial nerve. Any disruption leads to a loss of normal muscular tone and movement in that side of the face.
Preserving anatomical continuity of the nerve means that the nerve is intact and was not disrupted by the surgical procedure. Even with an intact nerve, the functional abilities of the nerve may not be complete. However, results from our series over the years have shown excellent results in terms of functional outcome of the facial nerve. In a recently reviewed series of over three hundred and eighty (380) patients who underwent a middle fossa-type approach at the House Ear Clinic, ninety-five percent (95%) of these patients maintained excellent facial nerve function after surgery. Only five percent (5%) suffered minor weakness of the facial nerve function. Preservation of facial nerve function is dependent to some degree on the size of the tumor that is removed.

One of the major recent focuses of acoustic neuroma surgery is the preservation of hearing. Major strides have been made in recent years in terms of improving the results of hearing preservation with surgery. Much like facial nerve results, the size of tumor is an influential factor. Also important is how well the patient hears prior to surgery. Hearing is determined by a test called an audiogram. This is performed by an audiologist. If the results of the audiogram indicate that the hearing level is sufficient to indicate a reasonable chance of success with saving the hearing during surgery, then a surgical approach is selected that is designed to save hearing. Otherwise, it may be advisable to choose a treatment approach that sacrifices hearing in order to obtain a total resection of the tumor.

Most patients with adequate pre-operative hearing levels have small tumors which are mostly confined to the internal auditory canal.  Continued refinements in this approach have led to superior hearing preservation results. Some patients also are candidates for a retrosigmoid approach. These are patients whom have small tumors that have only a small portion of the tumor located within the internal auditory canal. However, this is a minority of patients with acoustic neuromas who have only a small component in the internal auditory canal.  Any measurable level of hearing was preserved in eighty percent (80%) of those patients.

Email : neuro@braintumors.in

Acoustic Neuroma Treatments

The treatment goal for any benign brain tumor is to eliminate the tumor while preserving neurological function. Because of their location in proximity to delicate brain structures, acoustic neuromas are a complicated treatment problem. The best care for the patient with acoustic neuroma is provided by specialized professionals who have significant and on-going experience in their treatment. An acoustic neuroma is one of the small number or brain tumors that must be attended to by physicians who specialize in and frequently treat this condition.
The majority of patients diagnosed with acoustic neuroma do have treatment for the tumor. Because acoustic neuromas are typically benign, slow-growing tumors, the necessity for treatment is not usually urgent, allowing patients time to research their treatment options and find an experienced team to manage their care. Patients who decide to have their acoustic neuroma monitored rather than have radiation therapy or surgery for the tumor generally do not exhibit significance changes in the tumor over time as documented by MRI Scans. For those patients who require immediate treatment of their acoustic neuroma either because of its size, its growth or change in shape or the urgency of their symptoms, surgical removal of the tumor is the preferred method of treatment.

Email : neuro@braintumors.in

Forms of Acoustic Neuroma

Acoustic neuromas occur in two forms: sporadic and those associated with Neurofibromatosis Type II (NF II).
Approximately 95% of all acoustic neuromas are sporadic cases and are unilateral (affecting one ear). Patients with sporadic acoustic neuromas tend to begin having symptoms in middle age with the average being around fifty years old at diagnosis.
In contrast, those tumors associated with NF II are bilateral (affecting both ears) and account for approximately 5% of acoustic neuroma patients. NF II is a rare, genetic condition that affects one in 100,000 people in the United States. Patients with NFII develop benign tumors on both auditory nerves and may have to have both hearing nerves severed through tumor removal. Patients with NF II present at a younger age averaging around thirty years old when they first develop symptoms.

Email : neuro@braintumors.in

Diagnosis of Acoustic Neuroma

After patients have received routine auditory tests that show loss of hearing and speech discrimination (hearing sound but not understanding what is being said), the hearing care provider may perform an auditory brainstem response test (ABR, BAER or BSER). This test provides information on the passage of sound information along the path from the ear to the brain. The results may indicate that the acoustic nerve is not functioning optimally. If there is an abnormality in the ABR test, a detailed imaging test such as a CT (also called CAT) Scan or MRI is typically ordered.
A CT (CAT) Scan stands for Computerized (Axial) Tomography. The CT scanning device takes x-rays from many different angles and uses a computer to assemble them into a series of cross sections or 'slices' to provide a detailed look at the inside of the body. The CT Scan is painless but sometimes makes patients uncomfortable because they feel closed in during the time in which they are within the scanning device. The CT Scan has proven to be effective in locating acoustic neuromas, although small tumors that are still confined to the internal auditory canal may not show up on standard CT Scans. To assist in providing the clearest possible scan, for some brain scans, the patient may be given an injection of 'contrast medium' dye before the scan begins to make the images clearer.

MRI stands for Magnetic Resonance Imaging. An MRI Scan is a radiology technique that uses magnetism, radio waves, and advanced computer technology to produce images of body structures. The image and resolution produced by MRI is very detailed and can detect tiny changes of structures within the body. In the case of diagnosis for acoustic neuroma, gadolinium, a contrast agent, is used to increase the accuracy of the images. Gadolinium enhances the tumor making it easier to see. An MRI scan is a painless scan that has the advantage of avoiding x-ray radiation exposure and no known history of side effects.

Email : neuro@braintumors.in

Signs & Symptoms of Acoustic Neuroma

In the majority of patients, the first symptom of acoustic neuroma is a reduction of hearing in one ear. This hearing loss is often accompanied by tinnitus, sound in the ear that has no externally audible source, and is usually subtle and slow in progression. There may also be a feeling of fullness in the affected ear. These early symptoms are sometimes mistaken for normal changes of aging, delaying diagnosis.
Because the acoustic neuroma originates in the balance portion of the eighth nerve, a patient may experience unsteadiness and problems with balance as the tumor grows. Larger tumors can press on the trigeminal nerve causing facial numbness and tingling, which can be either occasional or constant.
Severe symptoms such as headaches, staggering and mental confusion can indicate an increase of intracranial pressure. Immediate attention is required as this pressure can be a life-threatening complication.
If you are experiencing any of these symptoms, we urge you to consult a physician so that a diagnosis can be established. If acoustic neuroma is diagnosed, early management is vital to your continued health.

Email:  neuro@braintumors.in

Acoustic Neuroma

An acoustic neuroma is a benign (non-cancerous) fibrous tissue growth that arises from the balance nerve (also called the eighth cranial nerve or vestibulocochlear nerve ) that leads from the brain to the inner ear. Acoustic neuromas are non-malignant, meaning that they do not spread to other parts of the body. An acoustic neuroma is sometimes also called a vestibular schwannoma or neurolemmoma.
Because acoustic neuromas are located deep inside the skull and are adjacent to vital brain centers in the brain stem, as these tumors grow, the affect surrounding structures in the brain that control vital functions. The brain is not invaded by the acoustic neuroma, but the tumor pushes on the brain as it enlarges. As the acoustic neuroma grows, it typically first affects a patient's hearing because it protrudes from the internal auditory canal into an area behind the temporal bone. Larger acoustic neuromas can press on another nerve in the area, the trigeminal nerve, which is the nerve affecting facial sensation. When large acoustic neuromas cause severe pressure on the brainstem and cerebellum of the brain, vital functions that sustain life can be threatened.
In the majority of cases, acoustic neuromas grow slowly over a period of years. In other cases, the growth rate is more rapid and patients develop symptoms at a faster pace. Usually the symptoms are mild and many patients are not diagnosed until some time after their acoustic neuroma has developed. Many patients also exhibit no tumor growth over a number of years when followed by yearly MRI scans.
Acoustic neuromas account for approximately 6% of all brain tumors. These tumors occur in all races of people and have a slightly higher occurrence in women.  Most acoustic neuromas occur spontaneously without any evidence of heredity and are diagnosed in patients between the ages of 30 to 60.

Email:  neuro@braintumors.in