Curriculum · ENT, Ophthalmology, and Dermatology
Acoustic neuroma (vestibular schwannoma)
What it is
Acoustic neuroma, the vestibular schwannoma, is a benign slow-growing schwannoma of the vestibular portion of CN VIII. It is the most common CPA tumor.
Causes and risk
The risk factors named are loud noise, radiation, a history of parathyroid adenoma, and neurofibromatosis type 2, in which the schwannomas are bilateral. In neurofibromatosis type 2 the schwannoma is the most common tumor, and the cranial nerve most often affected is CN VIII, the vestibulocochlear nerve, which is why hearing loss and tinnitus belong to it. It is autosomal dominant and the NF2 gene sits on chromosome 22. Its diagnostic criteria are met by any one of three sets: the first is bilateral vestibular schwannomas, that is bilateral acoustic neuromas; the second is a unilateral vestibular schwannoma together with a first-degree relative with NF2; and the third is a unilateral vestibular schwannoma, or a first-degree relative with NF2, together with any two of meningioma, nonvestibular schwannoma, ependymoma and cataract. The manifestation that typically appears first is the cataract.