Acoustic Neuroma

Introduction

Acoustic Neuroma is a benign (noncancerous) tumor arising from the vestibular nerve and so properly called as Vestibular Schwannoma. Acoustic neuromas account for approximately 80% of tumors found within the cerebellopontine angle. Acoustic neuromas grow from a type of cell called a Schwann cell. These cells cover the nerve cells. This is why the tumour is called a vestibular schwannoma. It is usually a slow growing tumor with a growth rate of 1.5mm/year. It commonly presents with hearing loss on one side and imbalance. Continued tumor growth may threaten neurological function and even life. Treatment for acoustic neuroma includes regular monitoring, radiation and minimally invasive surgical removal.

Symptoms

The signs and symptoms of acoustic neuroma develop from the tumor pressing on the adjacent nerves or brain structures. Initial symptoms are one-sided hearing loss, ringing in the ears (tinnitus) and problems with balance

  1. Hearing Loss - Hearing loss is mostly gradual although in a few cases it could be sudden as well. Hearing loss is first noticed for high pitched sounds like inability to clearly hear a telephone conversation on the side of tumor. The type of deafness caused is called sensorineural deafness and means the nerve for hearing (the acoustic nerve) is damaged. Hearing loss is often accompanied by ringing in the ear (tinnitus) or a feeling of fullness in the ear.
  2. Vertigo – It is the sensation of the room spinning around. This feeling of movement occurs even when you are standing still.
  3. Facial numbness, facial weakness, and taste changes – These symptoms occur as the tumor causes pressure on the fifth and seventh cranial nerves. As the tumor enlarges the commonly affected nerve is the trigeminal nerve or the 5th nerve which controls feeling in the face. This leads to episodes of severe facial pain (trigeminal neuralgia) or facial numbness. As the facial or seventh nerve is affected by the tumor it leads to facial weakness.

A large acoustic neuroma can cause multiple symptoms, including:

  1. Headaches with blurred vision
  2. Problems with limb coordination on one side of the body
  3. In rare cases, changes to the voice or difficulty swallowing
Acoustic Neuroma Treatments

There are three main courses of treatment

  • Observation
  • Surgery
  • Radiation therapy
  1. Observation
    • Small sized tumour causing only mild symptoms may not need immediate treatment. Acoustic neuromas tend to be very slow-growing and it may be a long time before symptoms require treatment. In this situation, you will have regular MRI scans to check for any growth of the tumour. In case the tumor appears to be growing in size surgery or radiation would be considered.
  2. MicroSurgery
    • In most cases if the acoustic neuroma is small it can be completely removed. For large tumours, a small part of the tumour may be left behind to help preserve the facial nerve. In cases where a small part of the tumour remains, it can either be monitored with MRI scans or effectively treated using radiosurgery. Using Key hole minimally invasive technique the tumor can be removed through a small opening in the skull just behind the ear (Retromastoid area)
  3. Radiation
    • Radiosurgery with a gamma knife or linear accelerator may be employed to reduce the size or limit the growth of the tumor. Radiation therapy is sometimes the preferred option for elderly patients, patients in poor health, patients with bilateral acoustic neuroma (a tumor affecting both ears), or patients whose tumor is affecting their only hearing ear.

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