The investigators study is to investigate safety and efficacy of performing a planned incomplete removal of large acoustic neuroma tumors to decrease surgical morbidity and yet avoid tumor recurrence by post-operative radiation therapy.

The current standard treatment of a large tumor of the balance nerve (acoustic neuroma or vestibular schwannoma) is surgical resection. Complete removal of such tumor is associated with significant risks of hearing loss and facial paralysis whereas incomplete removal of the tumor is associated with significant risks of regrowth. Stereotactic radiation is a well accepted therapy aiming at stopping the growth of smaller acoustic neuromas before their sizes become large enough to cause problems. The purpose of our study is to determine whether the combination of subtotal resection followed by stereotactic radiation of the remnant can control large acoustic neuromas without the significant risks associated with complete resection.

Inclusion Criteria:

• Adult patients with acoustic neuromas the widest diameter of 2.5 cm or larger at the cerebellopontine angle are eligible for this trial.
• Patients that are deemed good surgical candidates based on age, general health, genetic predispositions, and hearing in contralateral side would be included as the subjects of this trial.
• Although we would include patients with neurofibromatosis II in this trial, considering their genetic predisposition for recurrence, we would analyze their outcome as a separate group.

Exclusion Criteria:

• Patients who have received any form of treatment of their acoustic neuromas prior to enrollment in the study including surgery or radiation therapy.

Patients with large acoustic neuromas measuring 2.5cm in longest dimension in the cerebellopontine angle.