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Management of Acoustic Neuromas
(Vestibular Schwannomas)File 1: Introduction to Acoustic Neuroma Mananagement

by ROBERT G. OJEMANN, M.D. Congress of Neurological Surgeons Honored Guest Presentation
Originally Published Clinical Neurosurgery, Volume 40, Chapter 24, Pages 498-535, 1992
Used with permission of the Congress of Neurological Surgeons.
HTML Editor: Stephen B. Tatter, M.D., Ph.D.


Disclaimer: The information and reference materials contained herein are intended solely to provide background information. They were written for an audience of physicians. They are in no way intended to constitute medical advise. For medical advise a physician must, of course, be consulted.
Contents

INTRODUCTION

This chapter summarizes the consecutive surgical treatment of 410 patients with unilateral acoustic neuromas who were personally treated over a 14-year period from 1979 to 1992. Patients with bilateral acoustic neuromas are not included. All patients had a suboccipital approach. Although the approach was suboccipital, the patients were evaluated and managed by a team. The operations were done in corounction with an otologist surgeon who exposed the internal auditory canal and dissected the tumor in that area.

Over the years I have had the benefit of working with otological surgeons Drs. William Montgomery, Joseph B. Nadol, Jr., and Michael J. McKenna; neurosurgeon Dr. Robert Martuza; otoneurologists Drs. Alfred Weiss and Stephen Parker; neurologist-neurophysiologist Dr. Robert Levine; and neurophysiologist Dr. Stephen Ronner. All have made important contributions in the management of the series of patients I am reporting.

The chronological evolution of my experience with acoustic neuromas has been summarized in a 1992 publication (39). In the 1960s and 1970s there was a higher percentage of large tumors.

Our first goal was to improve the operative morbidity and mortality and increase the preservation of facial nerve function. This led to a plan utilizing the translabyrnthine operations for smaller tumors and a combined two-stage operation (translabrynthine and suboccipital approach) for larger tumors (44). This plan was successful in achieving our initial goals. The advent of computed tomography (CT) in 1973 was a major step in allowing earlier and more precise diagnosis of acoustic neuromas. An early publication summarized our experience with this study (7). Subsequently, the entire subject of diagnosis of cerebellopontine angle tumors was reviewed (28).

During the 1970s, as experience was gained in the use of the operating microscope and in microsurgical techniques, we found that for most tumors a one-stage suboccipital operation gave as satisfactory a result as our previous two-stage procedure. Occasionally, for large tumors a twostage suboccipital approach was used. I used the sitting position and experience with this approach was satisfactory, with a low operative mortality, a high percentage of patients returning to normal activity, and a significant preservation of facial nerve function (35, 36, 41).

In a few older patients I began to use a modified supine position to avoid the risk of hypotension (42). This position was more comfortable for the surgeon and more physiological for the patient, the worry over air embolus was removed, and there was excellent exposure of the tumor. Intermittent pulsation of cerebrospinal fluid into the operative area did not present a problem and tended to keep the nerves and vascular structures from drying.

In 1979 1 shifted to this position for almost all cerebellopontine angle tumors and experience with this approach has been reported (39, 42, 43). This is why the series reported in this chapter starts in 1979. At that time we were also starting to save hearing in some patients.

In December 1991 the National Institutes of Health held a Consensus Development Conference on acoustic neuroma (9). It was estimated that between 2000 and 3000 new cases of unilateral acoustic neuromas were diagnosed in the United States each year (an incidence of about 1 per 100,000 per year). The panel concluded that, "Treatment must be individualized and requires an experienced, well-integrated, multidisciplinary team. The question of whether and when to undertake treatment is complex. Currently, the ideal treatment is the total excision of the tumor in a single stage with preservation of neurological function" (9).

The need for research into the relative benefits and risks of all management options was stressed. In this report I present the microsurgical technique and the benefits and risks of the suboccipital approach for surgical removal of these tumors and suggest a management plan for patients with this tumor.

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