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At a 1991 Consensus Conference of the National Institutes of Health (NIH) regarding treatment options for patients with acoustic neuroma, surgical excision of the tumor was recommended as the therapy of choice for symptomatic acoustic neuromas due to its high rate of control, low rate of complications, low rate of tumor recurrence, and very low rate of mortality.

There are several important issues that must be considered in deciding to undergo surgical removal of an acoustic neuroma. These include:

• What is the status of hearing levels in the affected and unaffected ear?
• What level of hearing preservation (considered successful if postoperative hearing is within 15 dB of preoperative levels) can be expected after surgery?
• Which type of surgical approach is most appropriate for the patient?
• What is the age and overall health of the patient?

There are two types of surgical procedures for acoustic neuromas: partial tumor removal and total tumor removal. Both types are performed by neurosurgeons highly trained in microsurgery, a delicate type of surgery that is aided by specialized instruments and an operating microscope.

Partial Tumor Removal

While the ideal goal of surgery for acoustic neuroma is the complete removal of the tumor with a minimum of complications, there are cases in which there may be overriding circumstances which may prevent this goal from being achieved. When a patient is at high risk for postoperative complications, a health care provider may initially suggest partial tumor removal with the understanding that additional surgery or radiotherapy may be required in the future. The goal of partial tumor removal is to reduce the size of the tumor in a way that reduces the risk of complications to the patient. This may also reduce the risk of facial nerve complications that can often result from surgery. There is, however, still a risk of hearing loss with this type of surgery.

The surgeon may elect to perform a near-total resection in which a small part of the tumor may be left due to inaccessibility or other reasons. Alternatively, the decision may be made to perform a subtotal resection which leaves a larger segment of the tumor. The tumor recurrence rate following a subtotal resection is considerably higher than that following a near-total resection. Recurrences can usually be seen within the first 5 years post-surgery. If a subtotal resection is necessary, the surgeon may also consider supplementary stereotactic radiosurgery in order to reduce the risk of recurrence.

Following partial tumor removal, the health care provider will typically order periodic MRI's to monitor the potential growth rate of the remaining tumor.

Total Tumor Removal

Thanks to the development of new instrumentation and operating techniques, the risks associated with the total surgical removal of acoustic neuromas have been greatly reduced. The main goals of the surgeon are to remove the tumor without causing any damage to the patient's facial nerve (which can result in facial paralysis) or the patient's hearing ability. The surgery may last 8 to 12 hours.

In order to minimize the risk for facial nerve injury during surgery, the 1991 Consensus Conference of the National Institutes of Health recommended intraoperative facial nerve monitoring as the standard of care. Intraoperative monitoring of the facial nerve provides continuous feedback to surgeons as they approach the facial nerve during resection. Electrodes are placed on the face and responses to facial stimulation throughout the surgery (e.g., heat, cold, touch) are tracked by auditory and visuals feedback provided by a special machine. The NIH also noted that the surgery and monitoring must be done by highly qualified neurosurgeons.