What Is Acoustic Neuroma Causes Symptoms Diagnosis and Treatment
Acoustic neuroma also referred to as vestibular schwannoma, maybe a quite rare, noncancerous and a slow-growing tumour that happens on the most nerve – vestibular leading from the internal ear to the brain. The vestibular nerves are the eighth cranial nerves, which function by transmitting sound and equilibrium (balance) information from the inner ear to the brain.
This type of tumour usually grows slowly and does not spread through the body, instead, it affects hearing, balance and facial nerves of a patient. Though acoustic neuroma may be a non-cancerous tumour, it is often dangerous if they grow large and press against the brainstem or brain. As per the medical history and records of the patients, it is estimated that only one person in every 100,000 births is diagnosed with acoustic neuroma every year and this tumour can develop at any age and sex but most ordinarily found between the age of 40 to 50.
What is Acoustic Neuroma?
Acoustic neuroma is quite a brain disorder or a brain tumour. It is also called a benign tumour since it is non-cancerous. It is a tumour that grows very slowly in the body, but it can push against vital brain structures and become life-threatening if not treated.
The nerve along which the tumour develops inside the brain is understood as the auditory nerve and it controls hearing sense. Acoustic neuromas grow as a sort of cell referred to as Schwann cell and surround nerve cells. It tends to grow slowly and sometimes it's too small and doesn't cause any signs and symptoms, but at the upper stage of acoustic neuromas, they are capable of interfering with the vestibulocochlear nerves. The size of an acoustic neuroma can vary from 2cm to 4cm or maybe more than that.
Causes of Acoustic Neuromas
The main explanation for acoustic neuromas appears to be an abnormal or non-functioning of a gene on a chromosome- NO -22. This gene produces a tumour suppressor protein that helps in controlling the growth of Schwann cells by covering the nerves. The exact cause of this tumour is still not identified by any scientists, and as per the studies and evaluations, about 8 out of 100 cases are caused by neurofibromatosis type 2 (NF2). NF2 is a rare genetic disorder and causes benign tumours in the nervous system. In most of the cases, there is no identifiable cause, but there may be some risk factors, including:
Age
Long-term exposure to loud noise
A family history of acoustic neuroma
Exposure to radiations during childhood.
Symptoms of Acoustic Neuroma
The signs and symptoms of acoustic neuroma usually vary with the sort, size of a tumour. Some of the common symptoms of an acoustic neuroma are as mentioned below -
Earache
Vomiting
Dizziness
Headaches
Vision problems
Facial numbness
Unsteadiness or loss of balance
Weakness or loss of muscle movement
Loss of sensation to at least one side of the face and mouth
Loss of the sense of taste on the rear half the tongue
Tinnitus – a perception of noise or ringing within the affected ear
Loss of hearing, usually gradual and occur on just one side or affected ear.
Diagnosis of Acoustic Neuroma
Acoustic neuroma is often difficult to diagnose in the early stages because signs and symptoms develop gradually over time. If any of the symptoms are analyzed, then certain physical tests are administered to check the presence of a tumour on the most nerve – vestibular. The most commonly used diagnostic tests are:
Physical examination of an ear
MRI and CT scans of the head
Audiometry – A test to see the functioning of the ear
BAER – Brainstem auditory evoked response
Treatment for Acoustic Neuroma
The treatment usually depends on several factors, including:
Patient’s age
The general health of the person
The size and location of the tumour.
There are several different treatments available to cure or stop the expansion of the tumour. The major treatments:
Surgery
Microsurgery
Radiation therapy
Stereotactic radiosurgery.
FAQs on Acoustic Neuroma Vestibular Schwannoma Explained
1. What is an acoustic neuroma?
An acoustic neuroma is a noncancerous tumor that develops on the vestibulocochlear nerve (cranial nerve VIII), which connects the inner ear to the brain. It arises from Schwann cells that form the myelin sheath around the nerve, so it is also called a vestibular schwannoma. This tumor typically grows slowly and can affect hearing, balance, and facial nerve function.
2. Is an acoustic neuroma cancerous?
An acoustic neuroma is benign, meaning it is not cancerous and does not spread to other parts of the body. However, it can become serious if it grows large enough to compress nearby structures such as the brainstem or adjacent cranial nerves. Its impact is due to pressure effects rather than metastasis.
3. What causes an acoustic neuroma?
An acoustic neuroma is caused by abnormal growth of Schwann cells on the vestibular portion of cranial nerve VIII. In most cases, the exact cause is unknown. However, some cases are linked to mutations in the NF2 gene, especially in individuals with Neurofibromatosis type 2 (NF2), a genetic disorder characterized by multiple nerve tumors.
4. What are the early symptoms of acoustic neuroma?
The earliest symptom of an acoustic neuroma is usually gradual, one-sided hearing loss. Common early signs include:
- Unilateral sensorineural hearing loss
- Tinnitus (ringing in one ear)
- Mild balance problems or dizziness
These symptoms occur because the tumor affects the cochlear and vestibular branches of cranial nerve VIII.
5. How does an acoustic neuroma affect hearing and balance?
An acoustic neuroma affects hearing and balance by compressing the vestibulocochlear nerve, which carries auditory and equilibrium signals to the brain. Specifically:
- Pressure on the cochlear nerve causes hearing loss and tinnitus.
- Pressure on the vestibular nerve leads to imbalance and vertigo.
As the tumor enlarges, symptoms may worsen due to increased nerve compression.
6. What is the difference between acoustic neuroma and vestibular schwannoma?
There is no difference between acoustic neuroma and vestibular schwannoma; they are two names for the same tumor. The term acoustic neuroma describes its association with hearing, while vestibular schwannoma more accurately describes its origin from Schwann cells of the vestibular branch of cranial nerve VIII.
7. How is an acoustic neuroma diagnosed?
An acoustic neuroma is diagnosed primarily using MRI (Magnetic Resonance Imaging) with contrast. The diagnostic process typically includes:
- Hearing tests (audiometry) to detect sensorineural hearing loss
- MRI scan to visualize the tumor in the internal auditory canal or cerebellopontine angle
MRI is the most accurate method for confirming the presence and size of the tumor.
8. Where is an acoustic neuroma located in the brain?
An acoustic neuroma is located at the cerebellopontine angle, where the vestibulocochlear nerve enters the brainstem. It often begins in the internal auditory canal of the temporal bone and may extend toward the brainstem as it grows.
9. Can an acoustic neuroma cause facial numbness or weakness?
Yes, a large acoustic neuroma can cause facial numbness or weakness by compressing the nearby facial nerve (cranial nerve VII) or trigeminal nerve (cranial nerve V). Symptoms may include:
- Facial muscle weakness
- Numbness or tingling on one side of the face
- Reduced corneal reflex
These effects occur when tumor growth extends beyond the vestibulocochlear nerve.
10. What are the treatment options for acoustic neuroma?
Treatment options for acoustic neuroma include observation, radiation therapy, or surgical removal, depending on tumor size and symptoms. The main approaches are:
- Observation (watchful waiting) for small, slow-growing tumors
- Stereotactic radiosurgery to stop tumor growth
- Microsurgical removal for larger or symptomatic tumors
Treatment choice depends on factors such as patient age, hearing status, tumor size, and overall health.
