Acoustic neuroma

A vestibular schwannoma (VS) is a benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (8th cranial nerve). A type of schwannoma, this tumor arises from the Schwann cells responsible for the myelin sheath that helps keep peripheral nerves insulated. Although it is also called an acoustic neuroma, this is a misnomer for two reasons. First, the tumor usually arises from the vestibular division of the vestibulocochlear nerve, rather than the cochlear division. Second, it is derived from the Schwann cells of the associated nerve, rather than the actual neurons (neuromas). A vestibular schwannoma (VS) is a benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (8th cranial nerve). A type of schwannoma, this tumor arises from the Schwann cells responsible for the myelin sheath that helps keep peripheral nerves insulated. Although it is also called an acoustic neuroma, this is a misnomer for two reasons. First, the tumor usually arises from the vestibular division of the vestibulocochlear nerve, rather than the cochlear division. Second, it is derived from the Schwann cells of the associated nerve, rather than the actual neurons (neuromas). Approximately 2,000 to 3,000 cases are diagnosed each year in the United States (6 to 9 per million persons). Comprehensive studies from Denmark published in 2012 showed an annual incidence of 19-23 per million from 2002 to 2008, and over the last 30 years, the reported incidence has been increasing, until the last decade in which an approximation of the true incidence may have been found. Most recent publications suggest that the incidence of vestibular schwannomas has been rising because of advances in MRI scanning. Most cases are diagnosed in people between the ages of 30 and 60, and men and women appear to be affected equally. Most vestibular schwannomas occur spontaneously in those without a family history. One confirmed risk factor is a rare genetic mutation called NF2. The primary symptoms of vestibular schwannoma are unexplained progressive unilateral hearing loss and tinnitus and vestibular (disequilibrium) symptoms. Treatment of the condition is by surgery or radiation and often results in substantial or complete hearing loss in the affected ear. Observation (non-treatment) over time also usually results in hearing loss in the affected ear. Early symptoms are easily overlooked, sometimes mistaken for the normal changes of aging or attributed to noise exposure earlier in life, often delaying diagnosis. The most prevalent symptoms in patients suffering from vestibular schwannoma is hearing loss (94%), tinnitus (83%) and vertigo (49%). The first symptom in 90% of those with an acoustic neuroma is unexplained unilateral sensorineural hearing loss, meaning there is damage to the inner ear (cochlea) or nerve pathways from the inner ear to the brain. It involves a reduction in sound level, speech understanding and hearing clarity. In about 70 percent of cases there is a high frequency pattern of loss. The loss of hearing is usually subtle and worsens slowly, although occasionally a sudden loss of hearing may occur(i.e. sudden deafness). Hearing loss can vary from mild hearing loss to complete deafness. Unilateral tinnitus (ringing or hissing in the ears) is also a hallmark symptom of acoustic neuroma. Not all patients with tinnitus have acoustic neuroma and not all AN patients have tinnitus. Most of them do however, both before and after treatment. Since the balance portion of the eighth nerve is where the tumor arises, unsteadiness and balance problems or even vertigo (the feeling like the world is spinning), may occur during the growth of the tumor. The remainder of the balance system sometimes compensates for this loss, and, in some cases, no imbalance will be noticed.Balance or vertigo is the third most common symptom in patients with acoustic neuromas (50% incidence). The onset of these may be subtle, like disorientation in dark hallways, and be dismissed as age related decline. These symptoms tend to occur later in the development of the tumor. Vestibular schwannoma patients sometimes complain of a feeling that their ear is plugged or 'full'.