Conditions: Acoustic Neuroma
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What is an acoustic neuroma
Acoustic neuroma, also known as vestibular schwannoma, is a noncancerous tumor that develops on the vestibular cochlear nerve (cranial nerve VIII), the nerve that is responsible for balance and hearing. This nerve runs alongside the facial nerve (cranial nerve VII) through a narrow tunnel within the skull bone.
What causes an acoustic neuroma?
An acoustic neuroma typically forms on one side or the other, and is due to random genetic mutations. Less commonly, a specific inherited genetic disease called neurofibromatosis type 2 is the cause of both left and right acoustic neuroma formation in the same individual. Neurofibromatosis type 2 causes tumors in nerves throughout the body, including within and directly under the skin, but in some cases, the diagnosis of neurofibromatosis is made only with the diagnosis of bilateral acoustic neuroma.
Acoustic neuroma and hearing loss, tinnitus, and facial weakness.
Due to its location, an acoustic neuroma can interfere with the function of the hearing, balance, and facial nerves on the affected side. Since this bundle of nerves passes through a bony canal (the internal auditory canal) that has little room to spare, a growth on the nerve within this canal can pinch the nerve fibers and their blood supply. Even though the tumor typically grows very slowly, dysfunction of the facial and vestibular cochlear nerves may occur either gradually or suddenly as blood flow finally drops below a critical level to sustain the nerves. This may present as a change in hearing, an increase in tinnitus, or (less commonly) as a weakness of the facial muscles.
How is an acoustic neuroma diagnosed?
An acoustic neuroma is typically diagnosed based on radiologic imaging of the brain or part of the brain. Symptoms such as asymmetric sensorineural hearing loss, asymmetric tinnitus, or facial nerve weakness may be the impetus leading to obtaining imaging, or in other circumstances, imaging performed for another reason may incidentally demonstrate an acoustic neuroma. Magnetic Resonance (MR) imaging is the most accurate and detailed modality to image an acoustic neuroma, but a large tumor may be detected by computed tomography (CT) scanning.
How is an acoustic neuroma treated?
The treatment options for acoustic neuroma are dependent on several factors such as the size, location, and growth rate of the tumor. The most common approach to managing an acoustic neuroma is observation, where the tumor is regularly monitored for growth. If the tumor is small and not causing any significant symptoms, then the observation approach can be followed. Treatment options include radiation therapy, which uses high-energy beams to destroy the tumor cells, or surgery to remove the tumor. The treatment option advised by the doctor depends on the individual case of the patient.