Acoustic Neuroma
An acoustic neuroma is a benign tumor of the eighth cranial nerve, the acoustic nerve. The acoustic nerve is involved with the sense of hearing and with control of balance. It is located in the base of the skull near the brainstem. About 2,500 new cases of acoustic neuromas are diagnosed per year.

The most frequent and earliest symptom of an acoustic neuroma is hearing loss. This is due to pressure of the lesion on the eighth cranial nerve. The hearing loss is on the side of the tumor; the other side is unaffected. The hearing loss often is subtle at first; however, in some cases the loss can be quite rapid. Other symptoms can include tinnitus or ringing in the ear, dizziness and balance difficulty. If the tumor is large it may cause facial numbness or weakness. Rarely, patients may complain of headache. This is also most likely if the tumor is large.

A neurosurgeon may suspect a patient has an acoustic neuroma in cases of hearing loss in one ear. To confirm a diagnosis, a neurosurgeon will do an MRI. This imaging technique accurately identifies the location and size of the tumor, which is important in determining appropriate treatment.

Treatment options for acoustic neuromas include observation, which may be appropriate in some cases, surgery or radiation. The physician will go over all possible treatment options with the patient and recommend which is most appropriate.

Observation may be appropriate when the tumor is small, noted incidentally, or if the patient is medically too unstable from another cause to undergo intervention. Observation will usually involve serial MRI examinations at scheduled points in the future. In some cases where the patient has usable hearing in the affected ear, observation is appropriate to extend the ability to hear from the affected ear.

Surgical intervention is recommended for total removal of the lesion. This involves a craniotomy where a portion of the skull is removed to allow access to the brain and is then returned to position afterwards. This is also the only approach where the tissue can be examined and a definitive determination made as to its tissue type. The surgery is done with the operating microscope, which aids in identification of surrounding structures. In some cases hearing may be preserved; in many patients, hearing loss is so severe before surgery that it cannot be preserved. The postoperative course involves 24-36 hours in the intensive care unit and about five days in the hospital.

Stereotactic radiosurgery with the gamma knife is used for patients who do not wish to undergo a craniotomy and for patients who are not medically able to withstand surgery. This is a one-day procedure done while the patient is sedated but awake. The goal of radiosurgery is to halt progression of tumor growth. This occurs over time. Since the tumor is not removed, an absolute determination of the makeup of the tumor cannot be determined. Most patients have the procedure and are discharged home the same day or early the next morning. The gamma knife has been in use at St. Luke’s Medical Center, an affiliate of Midwest Neurosurgical Associates, since 1999. Approximately 50 patients are treated each year.

For more information, contact the Acoustic Neuroma Association at www.anausa.org.          

Brain Tumor
Brain tumors are divided into many classifications. A distinction is usually made between primary brain tumors, or tumors of the brain itself, and metastatic tumors, or tumors that originate elsewhere in the body and travel through the bloodstream to the brain. Another distinction is made between malignant or cancerous tumors and tumors that are benign. Primary brain tumors may be either benign or malignant. Metastatic tumors are malignant.

The classification of the tumor is determined after a biopsy. During a biopsy, some or all of the tumor is removed and the cells are examined under a microscope. Definitive treatment of the tumor cannot be started until a final diagnosis is completed after biopsy.

At the time of the initial biopsy, the surgeon will remove as much of the tumor as is possible without sacrificing function such as speech or movement. This may involve a full craniotomy, or opening of the skull, to allow access to the tumor. In cases where the tumor is adjacent to vital structures, a decision may be made prior to surgery to perform only a biopsy rather than attempting to remove the entire tumor. This is a smaller operation that may or may not involve attaching a headframe and opening only a small hole in the skull to allow for tissue samples to be removed.

Some brain tumors do not produce symptoms. Other times, symptoms may include headaches, especially at night, seizures or neurological difficulties related to speech, vision, numbness, weakness, balance or walking.

Meningiomas are tumors of the meninges or coverings of the brain. Typically they are benign. Acoustic neuromas or tumors of the acoustic (hearing) nerve and pituitary tumors are other common benign tumors. They may be treated with surgical resection (removal), radiation or stereotactic radiosurgery with the gamma knife. The type of treatment depends upon the size and location of the tumor, surrounding critical structures, and the patient’s general health and well-being.

Gliomas are malignant tumors of the brain itself. Gliomas are graded, or divided, into levels based upon their rate of growth and potential for rapid deterioration. The higher the grade, the more aggressive the tumor. Treatments for gliomas depend upon the grade and will typically involve a combination of therapies including surgical resection, chemotherapy and radiation. The rate of survival depends upon the grade of the tumor as well as the individual’s response to therapy.

The total treatment of brain tumors is a team effort. This involves the neurosurgeon, the medical oncologist, the radiation oncologist, their staffs and the patient and family. New treatments are being developed rapidly and the prognosis for patients with brain tumors is brighter than it ever was in the past.

For additional information about brain tumors and their treatment, you may wish to contact the American Brain Tumor Association at www.abta.org, or the National Brain Tumor Foundation at www.braintumor.org or the Acoustic Neuroma Association at www.anausa.org.

Trigeminal Neuralgia
Trigeminal neuralgia (also known as Tic doloroux) is a condition of excruciating facial pain. Often the pain can be triggered by activities such as touching your mouth, talking, eating, brushing your teeth, shaving, a cold wind or even a light breeze. These pains often last only moments, but the pain is so severe as to be incapacitating. About 15,000 new cases are diagnosed annually in the United States. It is caused by vascular compression of the fifth cranial (trigeminal) nerve. It may involve one, two or (rarely) three branches of the nerve. It rarely occurs on both sides of the face.

Treatment initially involves drugs such as Tegretol, Baclofen or Dilantin. If medical treatment is ineffective or if side effects of the medications are unacceptable, surgical treatment may be considered. The surgical approaches include:

• Peripheral nerve branch block with phenol alcohol
• Percutaneous trigeminal rhizotomy with glycerol, balloon or radiofrequency
• Microvascular decompression
• Stereotactic radiosurgery with gamma knife

Peripheral nerve branch block involves an injection into the nerve roots along the side of the head. Rhizotomy involves cutting a nerve root in the cheek. Microvascular decompression is brain surgery to place a sponge-like material between the trigeminal nerve and adjacent blood vessels to alleviate pressure from blood flow. The gamma knife is a scalpel-free method of brain surgery using beams of radiation. For additional information and support for this condition, contact the Trigeminal Neuralgia Association: www.tna-support.org.

Cyberknife
CyberKnife technology is the latest breakthrough in imaging and robotics
technology. A CyberKnife radiosurgery system makes no cuts or incisions
anywhere on a patient. By using precise and highly focused beams of
high-energy radiation, CyberKnife is able to destroy diseased tissue on a
tumor site. The technology is capable of treating the most complex and
difficult tumors, which include cancers of the lung, spine, pancreas or
brain.

A radiosurgery system uses a linear accelerator to create focused beams of radiation to the tumor site. Image guidance cameras are used to determine the exact shape and position of the tumor inside a patient's body. The linear accelerator is attached to a robotic arm and is able to deliver multiple beams of radiation that converge on the tumor. A concentrated dose
of radiation is delivered to the tumor, surrounding tissue has minimal exposure.

Advantages to using the CyberKnife system include no use of a a head or body frame to immobilize the patient. The intelligence technology is able to automatically correct for any patient movement. CyberKnife is able to continually scan and detect any patient or lesion movement and makes any necessary corrections. Additionally, the technology is able to track
respiratory motion and adjusts for patient breathing.

For more information, visit www.cyberknifesupport.org

Gamma Knife
Stereotactic radiosurgery with the gamma knife is not truly surgery at all. No knife is involved. Radiosurgery involves using multiple beams of low dose radiation, which converge on a target, thereby delivering a precise, very high dose of radiation to a specific area. The radiation causes the cells in the area to slowly die. They no longer replicate and the targeted lesion either stabilizes or shrinks in size. Gamma knife has been in use since 1968 but its use has increased more recently due to developments in diagnostic imaging such as magnetic resonance imaging (MRI).

Gamma knife can be used on multiple types of brain lesions including acoustic neuromas, trigeminal neuralgia, benign and malignant primary brain tumors, metastatic brain tumors, arteriovenous malformations and some functional disorders including Parkinson’s disease and tremor. In some cases gamma knife therapy may be used in conjunction with conventional radiation or with surgery. Not all conditions are appropriate for treatment with gamma knife. These include lesions, which are too large or located in especially sensitive areas.

The benefits of gamma knife include no risk of anesthesia, no incision, no hair loss, short hospitalization, immediate return to pre-procedure activities and minimal-to-no discomfort. Procedural risks are minimal and involve bruising at the headframe site and some minor discomfort when the frame is applied and removed. The headframe works with MRI to precisely target the tumor. Delayed risks involve possible effects of radiation or progression of the disease. These will be fully discussed prior to the decision to proceed with the gamma knife.

For more information about the gamma knife, call the Gamma Knife Center at 414-385-2660 or contact the International Radiosurgery Support Association at www.irsa.org.