This article includes discussion of vestibular schwannoma, acoustic neurinoma, and acoustic schwannoma. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
In this article, the author reviews the etiology, diagnosis, and management of vestibular schwannomas. Particular attention is given to treatment controversies, including the role of observation, surgery, and stereotactic radiosurgery/fractionated radiosurgery in the management of these tumors. The molecular etiology of these tumors is reviewed as new developments may lead to new medical treatment options for these tumors. Data on the role of noise exposure and the controversial role of cell phones in the development of vestibular schwannoma are reviewed.
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• Treatment options for vestibular schwannomas are rapidly evolving as new outcome data relevant to tumor control and quality of life are reported.
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• The molecular etiology of these tumors is being elucidated and may soon lead to novel medical treatments.
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• The causative role of cell phone usage as a cause of vestibular schwannoma continues to be controversial.
Historical note and terminology
Previously, and incorrectly, called acoustic neuromas, vestibular schwannomas (acoustic schwannoma, acoustic neurinoma) are benign neoplasms of Schwann cell origin arising from the vestibular branches of the eighth cranial nerve. Tumors originate distal to the point at which the oligodendroglial cells are replaced by Schwann cells, usually within the internal auditory canal. The majority of all schwannomas (85% to 90%) arise from the vestibular branches of cranial nerve VIII. Rarely, tumors can develop from the cochlear branch.
The tumor was described pathologically by Sandifort in 1777, but it was not for over a century that the diagnosis was first made clinically. The first successful removal was performed in 1894. However, early surgical approaches to these tumors were almost always fatal. Mortality in Henschen's series from 1910 was 85% (136). Improvements in surgical and anesthetic technique dropped this figure to 4% in Cushing's hands (71). It should be noted that Cushing restricted surgery to intracapsular decompression, believing total tumor excision to be too hazardous. Walter Dandy successfully added careful dissection of the residual capsule from surrounding structures and extirpated several acoustic tumors. The use of microsurgical techniques, a variety of surgical approaches, neurophysiological electrical monitoring, and improved neuroanesthesia have shifted the focus from patient survival to preservation of cranial nerve function.