An acoustic neuroma

An acoustic neuroma (vestibular schwannoma or neurolemmoma) is a benign tumour of the eighth cranial nerve. This nerve leads from the inner ear to the brain. Whilst a proportion of tumours will not grow or grow very slowly, growth will ultimately result in brainstem compression (as in this example), hydrocephalus, and brain stem herniation and death. It is diagnosed on MRI with gadolinium contrast as shown. The neuromas extension into the right internal auditory meatus can be seen on coronal MRI. The exact cause is unknown – most people with acoustic neuromas are diagnosed between the ages of 30 and 60. Due to advances in microsurgery, including intraoperative monitoring of facial and cochlear function, the risks of facial paralysis and hearing loss have been greatly reduced – many tumours can now be treated effectively with both surgery and targeted radiation therapy (gamma knife). The outcomes for small acoustic neuromas are better while those larger than 2.5 cm are likely to experience significant hearing loss post surgery.