A vestibular schwannoma, sometimes called an acoustic neuroma, is an uncommon, nonmalignant tumor involving the vestibulocochlear nerve (the nerve between the ear and the brain that transmits hearing and balance signals), or less commonly the inner ear itself. It usually presents with gradually progressive hearing loss on one side, and sometimes with imbalance. The diagnosis may be suspected based on results of hearing and balance testing, and confirmed with an MRI of the inner ear without and with contrast. Vestibular schwannomas sometimes do not grow at all, or only grow very slowly, so monitoring symptoms (and sometimes repeating imaging) is appropriate in some cases. In other cases, intervention may be required, and this can be in the form of radiation therapy (to shrink the tumor) or open surgery (to remove or debulk the tumor). Symptoms of imbalance may transiently worsen after surgery, and some patients benefit from vestibular rehabilitation therapy.