• Conditions Treated

  • Arteriovenous Malformation
  • Bone Metastases
  • Brain Tumors
    • Gliomas
    • Brain Metastases
    • Pituitary Adenoma
    • Meningioma
    • Acoustic Neuroma
  • Kidney Tumors
  • Liver Tumors
  • Lung Tumors
  • Ocular / Orbital Tumors
  • Pancreatic Cancer
  • Prostate Cancer
  • Spinal Tumors
  • Trigeminal Neuralgia

Acoustic Neuroma

A benign, slow-growing tumor type, acoustic neuromas affect the seventh and eighth cranial nerves in a part of the brain known as the cerebellar-pontine angle, or CPA. The eighth cranial nerve has two parts – the cochlear nerve that transmits sound between the inner ear and the brainstem, and the vestibular nerve that helps provide balance.

Acoustic neuromas most commonly arise from schwann cells, which produce insulation for the vestibular nerve. Therefore, these tumors are often called vestibular schwannomas.

What are the symptoms?

Early symptoms include hearing loss or deafness, pressure in the inner ear, impaired sense of balance and ability to walk, as well as vertigo with associated nausea and vomiting. About 80 percent of patients reported tinnitus, usually high-pitched ringing, roaring or hissing sounds.

Large tumors that press against the brainstem may affect other cranial nerves that result in less common symptoms like the loss of sensation in the face and mouth or altered swallowing and gag reflex. Larger tumors also may lead to increased intracranial pressure and associated symptoms like headache, vomiting and altered consciousness.

What are the treatment options?

Medical understanding of acoustic neuromas has changed dramatically over the past 20 years and continues to evolve. As a result, there is no consensus on a single best treatment. Each one has merits and risks.

CyberKnife Center of Chicago is capable of treating acoustic neuromas, but we encourage patients to thoroughly review and understand all treatment options. The information presented here is not all-inclusive. Rather, it represents a starting point for patients to learn more about treatment options.

Surgical removal

Surgical removal has been the standard treatment for more than 50 years, and medical advances like microsurgery, or microscope-assisted surgery, have greatly improved outcomes. Even in successful procedures, patients can experience facial weakness and hearing loss. Like all open surgery, this method also carries the risk of further complications, in this case spinal-fluid leaks or infections, among others. Stroke and death during surgery are rare but possible.

For patients with a large acoustic neuroma – a diameter of more than 4-5 centimeters – that affects brain function, it is widely believed, though not universally, that the treatment of choice is removing the tumor through open microsurgical resection. Often such surgery cannot be delayed and is lifesaving. For the vast majority of patients with smaller acoustic neuromas, stereotactic radiosurgery with the CyberKnife offers an important treatment option.

Stereotactic radiosurgery

Stereotactic radiosurgery has been used for destroying brain tumors, including acoustic neuromas, for about 20 years. The procedure has evolved during that time, and several studies have reported very favorable long-term clinical outcomes. As a result, radiosurgery is an effective alternative for many patients with acoustic neuromas. The CyberKnife’s ability to offer hypo-fractionated, or staged, treatments lowers associated risks even further.

Single-session radiosurgery

Single-session radiosurgical systems like the Gamma Knife were introduced in the early 1990s. These require a metal frame attached to the patient’s skull with screws to achieve accurate targeting for the radiation. Because the frame is relatively uncomfortable, single-session treatment is the only practical way to perform this kind of radiosurgery. Despite its limitations, single-session radiosurgery has ushered a revolution in the management of acoustic neuromas and defined the gold-standard treatment.

Advancements in radiosurgery include better imaging for targeting, more complex shaping of the radiation beams and improved understanding of optimal radiation dosing. As a result, patients treated with single-session radiosurgery have at least a 98 percent chance of tumor control. The chance of facial-nerve injury is only 1 percent, and useful hearing is saved for more than half of all patients, though the rate of hearing preservation is difficult to predict.

For acoustic neuroma patients who have already suffered significant hearing loss, single-session radiosurgery continues to represent an important treatment alternative to surgery.

Staged or fractionated radiosurgery

Staged, or fractionated, radiosurgery spreads treatment over multiple sessions, usually between three and five. Fractionated radiosurgery allows time for healthy tissues like the cochlear and facial nerves to recover from radiation between treatments.

With typical dosing, fractionated radiosurgery carries almost no risk of facial-nerve injury. About 85 percent of patients still have hearing two years after radiosurgery. The remaining 15 percent experience some hearing loss, though it’s often not severe. Since doctors began using fractionated radiosurgery, there appears to be almost no risk of complete deafness. More studies are needed on how treatment affects hearing. So far, however, clinical experience and theory suggest fractionated radiosurgery should be the safest of all acoustic neuroma treatments.