affecting the central nervous system. Acoustic (ah-KOOS-tik): Related to sound or hearing. Acoustic Neuroma (an-ah-PLAS-tik): An acoustic neuroma, also called a vestibular schwannoma, is a benign intracranial tumor of the myelin -forming cells of the vestibulocochlear nerve (CN VIII). For more information, see: Acoustic Neuroma Diagnosis and Treatment Anaplastic (an-ah-PLAS-tik): A