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Acoustic neuromas typically originate at a point on the vestibulocochlear nerve that is located in the internal auditory canal. Acoustic neuroma tumors may grow for many years before becoming symptomatic. They rarely shrink on their own and must, therefore, be observed carefully and treated after they have been diagnosed. The growth rate ranges from no growth or slow growth to fast growing (greater than 1.0 cm/yr). The tumor may either consistently follow one growth pattern or may alternate its rate of growth at different periods of time.

An acoustic neuroma typically remains encapsulated and as it grows it slowly displaces the surrounding tissue and nerves. The tumor first distorts the 8th cranial nerve from which it develops and then may press on the 7th cranial nerve which becomes stretched over the tumor. If left untreated, the tumor grows to the point of filling the internal auditory canal and then may grow into the cerebellopontine angle or may begin to erode the surrounding bony structure. It takes on a pear-like shape and may begin to press on the 5th cranial nerve, the trigeminal nerve, which is responsible for facial sensation. Although the tumor does not actually invade the brain, the pressure of the tumor can displace brain tissue. If it compresses brain structures that control vital body functions, an acoustic neuroma can become life-threatening.

Tumor growth rate at one year following diagnosis is thought to be a strong predictor regarding the eventual need for treatment. However, tumors that are larger than 2.5 cm at the time of diagnosis are considered more likely to grow than smaller size tumors. In addition, an enlarged tumor may press on other nerves and alter facial sensation, swallowing, and vestibular function such as balance and hearing. Hearing loss, which occurs in approximately 90-95% of patients, is usually caused either by compression of the cochlear nerve or the blood vessels which supply the cochlea.

It is of utmost importance for patients who are diagnosed with an acoustic neuroma to be under the care of a specialist. Health care professionals usually involved in the treatment of acoustic neuroma may include an otolaryngologist, neurotologist (an ear-nose-throat medical specialist who obtains an additional subspecialty in conditions of the ear), neurosurgeon, radiotherapist (a specialist in radiotherapy), interventional radiologist, and audiologist.