Acoustic neuroma is a rare benign tumor arising on the vestibular branch of VIII cranial nerve. This nerve leads from brain to inner ear. The nerve is involved in two functions; transmission of sound from inner ear to brain and sending balancing signals to the brain. The covering of vestibular nerve is made up of Schwann cells. Tumor arises from overproduction of Schwann cell and hence it is also called ‘vestibular schwannoma’.
Most common symptom of acoustic neuroma is orofacial pain, hearing loss, ringing in ear, imbalance, and facial paralysis. This occurs due to compression of the cranial nerves by the growing tumor.
Possible Causes Of Acoustic Neuroma
Acoustic neuroma develops from the Schwann cells of VIII cranial nerve. Schwaan cell sheath is an insulating covering the vestibular nerve. The tumor arises from these cells due to overproduction. The exact mechanism for rise of tumor is not known. Acoustic neuroma is of two type; sporadic form and other associated with a condition called neurofibromatosis type 2 (NF2).
NF2 is an inherited disease and is responsible for acoustic neuroma in both sides of the ear. Sporadic acoustic neuroma may occur spontaneously with no clear cause. It is usually unilateral meaning, occurring only on one side of the ear. Environmental problems are known to contribute its spontaneity. Person exposed to loud sound constantly for long time is at risk for development of acoustic neuroma. Exposure to radiation on head and neck can also lead to acoustic neuroma.
Signs And Symptoms Of Acoustic Neuroma
The signs and symptoms of acoustic neuroma usually take many years to develop as the tumor is slow growing. Symptoms occur due to pressure on the nerve. Also the facial nerve is adjacent to the tumor hence it can also get affected. Following are commonly encountered symptoms of acoustic neuroma:
- Hearing loss of one side.
- Ringing in ear
- Loss of balance and unsteadiness of posture.
- Dizziness
- Numbness and tingling on face.
- Facial paralysis if facial nerve gets compressed.
- Pain in face
- Unexplained headache
- Feeling of fullness as if the ear is plugged.
Acoustic Neuroma Diagnosis
Diagnosis becomes a challenging task because most of the time early symptoms are overlooked by the patient or they are similar to other middle ear and inner ear diseases. Besides, most symptoms in their initial stage are subtle. The first symptom in majority of cases is reduced hearing in one ear. The doctor takes note of all the symptoms during examination and medical history.
Primary diagnostic procedure includes examination of ear and tests related to hearing which is also called audiometry. Diagnosis is confirmed with the help of CT and MRI scan. Both this imaging techniques help to locate and identify the size of tumor. Early diagnosis is key for successful treatment in acoustic neuroma.
Treatment Options For Acoustic Neuroma
The treatment of acoustic neuroma depends on many factors. It may depend on whether the patient is experiencing any symptoms. It will also depend on the size of tumor and rapidity of tumor growth as well as patient’s health status and his age. Hence if the tumor is growing slowly over a period of time with few or no signs and symptoms, patient may be just monitored regularly. He may not require any aggressive therapy.
If the symptoms are severe or if the benign growth is large surgery may become essential. However, surgery has its own complications such as hearing loss, facial paralysis, etc. Hence the surgeon usually weighs benefits and cons before surgery. Radiation therapy is another alternative particularly for patients who cannot tolerate surgery for health reasons, or if the tumor is small in size.