An acoustic neuroma, or vestibular schwannoma, is a benign, or non-cancerous, tumor in the ear. The tumor may need to be removed as it grows and presses on structures around it. Acoustic neuroma surgery is the best option to cure the condition, and the operation usually requires a stay in the hospital and a general anesthetic. Most often, hearing in the affected ear is lost, although with some small tumors it may be possible to preserve it.
Acoustic neuromas are formed from Schwann cells, which form an insulating layer covering nerves. An acoustic neuroma typically grows from Schwann cells on the acoustic nerve, also known as the vestibulocochlear nerve. As this nerve is involved in balance and hearing, the neuroma may cause symptoms such as dizziness, hearing loss and ringing in the ears, or tinnitus.
For a patient with a small tumor which has not caused hearing loss, a suitable type of acoustic neuroma surgery might be a procedure known as the middle fossa approach. With this operation, there is a chance that the patient's hearing might be preserved. A hole is cut in the skull above the ear and the neuroma is removed from the inner ear.
Where hearing has already been lost, a type of acoustic neuroma surgery called the translabyrinthine approach may be used. Here, an opening is made in the skull behind the ear and part of the inner ear is removed together with the tumor. A piece of fat from the belly is used to block up the hole through which brain fluid might otherwise leak.
Acoustic neuroma surgery can involve the use of special surgical instruments, such as an ultrasound tool which fragments the center of the tumor using sound waves and extracts the pieces using suction. The ability to hear may be monitored during an operation by playing sounds and recording responses in the area of the brain responsible for hearing. Even in the best situation, the chance of saving hearing may only be around 40 percent.
After acoustic neuroma surgery, if hearing has been lost in one ear, a pair of hearing aids can be fitted which take the sounds from the affected ear and carry them to the functioning ear. This can help a person locate which direction sounds are coming from. Sometimes acoustic neuroma surgery damages the nerve which supplies the muscles of the face, causing one-sided facial weakness and difficulty swallowing and speaking, but this often improves with recovery. Tinnitus does not usually improve after neuroma surgery, so some form of tinnitus therapy may be required. Problems with balance commonly occur following the operation, and it can take several months for patients to adjust.
