Acoustic Neuroma (Vestibular Schwannoma): An Overview
Illness and Condition
Acoustic neuroma, also known as vestibular schwannoma, is a benign (non-cancerous) tumour that develops on the vestibulocochlear nerve, which connects the inner ear to the brain. This nerve is responsible for hearing and balance, and the tumour arises from Schwann cells that form the nerve’s protective covering. Although the tumour is non-malignant, it can cause serious complications by pressing on nearby nerves and brain structures.
Symptoms
The symptoms of acoustic neuroma typically develop gradually and may vary depending on the tumour’s size and location. Common symptoms include:
- Hearing loss, usually gradual and on one side
- Tinnitus (ringing or buzzing in the ear)
- Balance problems or unsteadiness
- Vertigo (a spinning sensation)
- Facial numbness or weakness if the tumour presses on the facial nerve
- Headaches or a feeling of fullness in the ear
Causes
The exact cause of acoustic neuroma is not fully understood. However, it is associated with genetic mutations in the NF2 gene, which controls the production of a protein called merlin that regulates cell growth. Most cases occur sporadically, but in rare instances, acoustic neuroma is linked to a hereditary condition called neurofibromatosis type 2, which causes tumours to develop on multiple nerves.
Diagnosis
Diagnosis of acoustic neuroma involves a combination of clinical evaluation and imaging studies. The process includes:
- Detailed medical history and physical examination, focusing on hearing and balance
- Audiometric tests to assess hearing function
- Magnetic Resonance Imaging (MRI) with contrast, which is the gold standard for detecting and characterising the tumour
- Sometimes, auditory brainstem response (ABR) testing may be used to evaluate nerve function
Treatment
Treatment options depend on the tumour size, growth rate, symptoms, patient age, and overall health. They include:
- Observation: Small tumours with minimal symptoms may be monitored regularly with MRI scans and hearing tests.
- Surgery: Removal of the tumour may be necessary for larger or symptomatic tumours. Surgical approaches vary and aim to preserve nerve function as much as possible.
- Radiation therapy: Stereotactic radiosurgery (such as Gamma Knife) is a non-invasive option that uses focused radiation to stop tumour growth, often used for smaller tumours or patients who are not surgical candidates.
Prevention
There is no known way to prevent acoustic neuroma since most cases are sporadic and related to genetic factors. However, early diagnosis and management can help prevent complications. Measures to protect hearing, such as avoiding excessive noise exposure and regular hearing check-ups, may be beneficial, especially for individuals with a family history of neurofibromatosis type 2.
In summary, acoustic neuroma is a treatable benign tumour that requires timely diagnosis and appropriate management to maintain quality of life and prevent neurological complications.