An acoustic neuroma is a tumor that grows from the nerves responsible for balance and hearing. These tumors grow from the sheath covering the vestibulocochlear nerve. Acoustic neuromas are benign not cancer and usually grow slowly. Over time the tumor can cause gradual hearing loss, ringing in the ear, and dizziness.
Because of their slow growth, not all acoustic neuromas need to be treated. Treatment options include observation, surgery, and radiosurgery. The ear is our organ of hearing and balance. It consists of three parts: the outer ear, the middle ear, and the inner ear. The middle and inner ear are located deep in the temporal bone of the skull. The vestibulocochlear nerve eighth cranial nerve is responsible for relaying hearing and balance signals from the inner ear to the brain.
The outer ear funnels sound down the ear canal to the eardrum, which vibrates three tiny bones called ossicles malleus, incus, and stapes in the middle ear Fig. In turn, the stapes vibrates the oval window of the cochlea in the inner ear. The spiral-shaped cochlea is filled with liquid, which moves in response to vibrations. As the fluid moves, thousands of hair cells are stimulated, sending signals along the cochlear nerve, which are processed as hearing in the brain.
Attached to the cochlea are three semicircular canals positioned at right angles to each other. The three canals are able to sense head position and body posture. Electrical signals from the semicircular canals are carried to the brain by the superior and inferior vestibular nerves responsible for balance. The cochlear and vestibular nerves form a bundle inside the bony internal auditory canal before exiting to reach the brainstem.
Inside the canal, the vestibulocochlear nerve lies next to the facial nerve. The facial nerve seventh cranial nerve is responsible for moving the muscles of the face.
