Release: Embargoed until September 24, 2000Contact: Jennifer Felsher202-371-4517 (9/23-27)703-519-1549[email protected]
SUCCESSFUL RECOVERY FOLLOWING SURGICAL REMOVAL OF ACOUSTIC NEUROMA IS DEPENDENT ON A VARIETY OF FACTORS
A new study suggests that tumor size and surgeon's experience are key factors in acoustic neuroma surgery to preserve hearing and avoid facial nerve damage
Washington, D.C. -- An acoustic neuroma (a type of tumor that develops from nerve sheaths of the auditory nerve) can lead to life threatening conditions if untreated. Even with microsurgery, the patient may be at risk for less than full recovery of normal hearing and facial nerve damage. The 1991 National Institutes of Health Consensus Statement estimated that 2,000 to 3,000 new cases of unilateral acoustic neuroma are diagnosed in the United States each year, yielding approximately one case per 100,000 people.
New research findings suggest that tumor size and surgeon's experience are key factors that determine patient's recovery after acoustic neuroma removal. The study, "Long Term Results of the First 500 Cases of Acoustic Neuroma Surgery", is authored by Richard J. Wiet, MD, FACS, Chief of Otolaryngology at Evanston Hospital affiliated with Northwestern University Medical School, Bulent Mamikoglu, MD, Linda Odom, MA, and Dick Hoistad, MD, all of Evanston Northwestern Health Care System in Evanston, IL. Dr. Wiet will present the findings on Monday, September 25, 2000, at the Annual Meeting of the American Academy of Otolaryngology -- Head and Neck Surgery Foundation, being held September 24-27, at the Washington, DC Convention Center.
There are many factors that may contribute to outcomes in acoustic neuroma surgery, such as age of the patient and tumor size. However, this study is significant in that it provides a direct comparison to surgical ability as it uses the retrospective data of one surgeon over the length of his practice. Although the potential for side effects is typical with any surgery, the delicate nature of acoustic neuroma surgery provides for dramatic outcomes. Facial nerve paralysis is the most common potential side effect of surgery and hearing preservation can be attempted in certain patients.
This study compares the outcomes of patient's facial nerve status and hearing preservation with the level of surgical experience. Factors such as age, and size of tumor were also taken into consideration. In this retrospective study, the authors were able to demonstrate that tumor size and surgical experience are the most significant factors influencing facial nerve status and hearing outcome.
Methodology: Five hundred patient records were reviewed retrospectively for analysis of outcome results of acoustic neuroma surgery conducted by the senior author, Dr. Wiet, with a neurosurgery team over a 19 year period of his practice (1980-1999). All surgeries were performed in a suburban hospital or tertiary care center with academic affiliation. The focus was on two outcome results: facial nerve status and hearing preservation. Each result was analyzed by surgical approach, tumor size, patient age, gender, and level of surgical experience.
The House Brackmann scale was used for measurement of facial nerve function pre- and postoperatively. Postoperative interval evaluations were performed immediately following the surgical procedure and again at one year. Guidelines of the American Academy of Otolaryngology -- Head and Neck Surgery Committee on Hearing and Equilibrium were use to classify hearing preservation.
Results: It was found that positive outcomes of facial nerve function (both immediate and at one year follow up) with removal of tumors of the same size were significantly higher during the last five years of the surgeon's career versus the first five years. Good postoperative facial nerve functions are observed in 75 to 92.5 percent of patients with tumors equal or less than 3 centimeters. However, for tumors greater than 3 centimeters, the facial nerve outcome tends to be poorer, regardless of surgical experience. Patient age was shown to have slight contribution to poorer facial nerve outcome, gender was not.
Hearing preservation was attempted in 96 patients, with a 43 percent positive outcome. The success of hearing preservation was also shown to be connected to surgical experience. Preoperative hearing levels were preserved in approximately 2/3 of patients operated on in the last 5 years. The size of the tumor also had a significant impact on hearing preservation: the larger the tumor, the less preservation.
Conclusion: This study demonstrates that tumor size and surgical experience are the most significant factors influencing the facial nerve status and hearing outcome following microsurgical removal of acoustic neuroma. Early diagnoses before large tumors are detected give the best outcome.
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