What is the pathogenesis of Acoustic Neuroma?

March 08 00:30 2019 Print This Article

It occurs sporadically and in few cases it occurs as a part of von recklin hausen neuro fibromatosis. The neuroma may take either of two forms.

In the case of type I neuro fibromatosis the schwannoma involves the 8th nerve sporadically. It occurs in the adult life and may involve the other cranial nerve or spinal root. The bilateral types are rare. In the case of type II neuro fibromatosis the schwannoma involves the individuals which are below the age of 21. They involve the entire nerve and are autosomal dominant in nature. Their incidence is around 5 to 10 percent.

The tumor starts as a solitary mass which originates in the nerve. It arises from the internal auditory canal as a vestibular portion of the 8th nerve. The tumor extends into the posterior part and goes into the angle between the cerebellum and pons. It may also exert pressure on the 5th and 7th cranial nerve. It may also involve the 9th and 10th cranial nerve. It also puts pressure on the pons and lateral medulla which leads to the obstruction of the CSF. It may lead to increase in the intra cranial pressure. The schwannomas can also occur in the relation to cranial and spinal nerve roots.

They compress the spinal cord and cause radiculopathy. The second most common form of the schwannomas is the trigeminal nueroma which involves the cranial nerves. The schwannomas of other cranial nerves are not so common.

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