Long-term hearing preservation after acoustic neuroma surgery.

The past two decades have evidenced a remarkable improvement in the capacity of otologic surgeons to treat cerebellopontine angle tumors. Advances in instrumentation because of technologic changes, coupled with better surgical training, have contributed to a highly successful rate of tumor removal. The capability to extirpate the tumor now permits the otologic surgeon to attempt simultaneous preservation of the facial and cochlear nerve functions. Just as middle ear surgery improved to the point in the 1950s that reconstruction as well as disease eradication became possible, so can surgeons now consider preservation of function of the inner ear. It is now technically feasible--in some instances--to attempt to preserve hearing in tumors of the eighth nerve. Several studies have provided evidence that the cochlear nerve can be anatomically and functionally preserved when neuromas involve either the inferior or superior vestibular nerves. However, other studies assert that grossly intact nerves may contain microscopic islands of tumor cells intermingled with nerve fibers. If viable tumor cells were allowed to remain behind, one would expect them to grow; this would result in loss of hearing function and tumor recurrence, as evidenced by computed tomography (CT) or magnetic resonance imaging (MRI). This article will discuss the issues of cochlear nerve preservation and tumor excision, and review our experience over the past decade.