ACOUSTIC NEUROMAS

Schwannomas

Schwannomas are benign tumors of Schwann cells. Most schwannomas are caused by Neurofibromatosis Type 2, and most are found on cranial nerves. They are easy to remove and have an excellent prognosis. They rarely become malignant. The most commonly involved cranial nerve is CN 8, although sometimes CN 5 is affected. Schwannomas of CN 8 are often called Acoustic Neuromas (a term that is technically incorrect because it is part of the myelin and not the neuron, but old names die hard). Schwannomas cause symptoms if they create a mass effect. Acoustic Neuromas tend to cause sensorineural hearing loss (but vestibular function is usually spared) when it compresses CN 8, and it sometimes compresses the nearby CN 7.