When a benign, or non-cancerous, tumor develops on the vestibular cochlear nerve (found behind the ear and beneath the brain, it’s responsible for hearing and balance) an acoustic neuroma—also known as vestibular schwannomas—is the typical diagnosis. Because they’re benign, acoustic neuromas don’t spread, and are known to grow very slowly. And although they don’t spread they can, when they reach a certain size, put pressure on the brain as well as damage adjacent nerves.

Acoustic neuromas have no known cause specifically, but genetic factors as well as years of exposure to loud sounds may lead to their formation, as can prior exposure to radiation in the head and neck.

The symptoms from this type of tumor are often unnoticeable, at least until it reaches a certain size. At this point signs may include changes in hearing, such as ringing in the ears, as well as some degree of hearing loss. Additionally, sufferers may experience headaches, ear pain, problems with balance, persistent drowsiness and numbness or tingling in the face. And in more severe cases, some cognitive problems may occur.

A physician seeking to diagnosis an acoustic neuroma will begin by ordering an audiogram—which tests hearing ability and may determine problems with hearing loss and speech problems— and an auditory brainstem response test which uses a computer to measure nerve response to different sounds. Also, image technologies such as CT scans and MRIs will be used as each can detect these often small and elusive tumors.

Finally, in treating acoustic neuroma radiation therapy has been shown to be particular effective. But depending on the size and location of the tumor, surgery may be required in order to ensure that the entire growth is removed.