What is a Schwannoma?
Schwannomas are tumours that arise from Schwann cells, which form the protective covering (called the myelin sheath) around peripheral nerves and help facilitate rapid nerve conduction. Although they may occur near the brain and spinal cord, schwannomas arise from peripheral nerve sheath cells and are therefore considered tumours of the peripheral nervous system.
Schwannomas are typically benign and are classified as World Health Organization (WHO) grade 1 tumours. Malignant transformation is very rare but malignant peripheral nerve sheath tumours can occur in people with genetic conditions such as neurofibromatosis type 2 or schwannomatosis. Because of their generally slow-growing nature, these tumours are often monitored with imaging and only treated if they grow, cause symptoms, or threaten important nerve function.
Many schwannomas develop due to inactivation of the NF2 tumour suppressor gene. Loss of NF2 function results in absence or dysfunction of the protein Merlin, which normally regulates cell growth and signalling pathways. When Merlin function is impaired, multiple growth-signalling pathways become deregulated, allowing Schwann cells to proliferate and form tumours.
Schwannomas most commonly arise along cranial nerves, spinal nerve roots, and peripheral nerves.
Types of Schwannoma
Schwannomas can develop along different nerves in the body. Doctors often describe them by where they grow, because the tumour’s location strongly influences the symptoms and treatment approach.
A tumour that arises from Schwann cells lining the vestibular portion of the vestibulocochlear nerve (the eighth cranial nerve). This nerve carries signals responsible for hearing and balance. The tumour has historically been called an “acoustic neuroma,” but the term vestibular schwannoma is more accurate because it originates from Schwann cells rather than the nerve tissue itself.
Although vestibular schwannomas are benign and almost never become malignant, they can still cause significant problems. As the tumour grows, it may compress nearby structures, including the brainstem and neighbouring cranial nerves. Because it affects the hearing and balance nerve, common symptoms include gradual hearing loss, tinnitus (ringing in the ear), and balance problems.
In addition to vestibular schwannomas, other types of schwannomas exist:
Typically benign tumours that grow from nerve sheaths along spinal nerve roots within the spinal canal or just outside it.
Can develop along almost any peripheral nerve in the body, because Schwann cells are present throughout the peripheral nervous system. This kind of schwannoma may also arise in less common locations such as the hand, foot or ankle.
Schwannoma Symptoms
Symptoms of a schwannoma depend largely on where the tumour grows and how much pressure it places on nearby nerves or brain structures. Some schwannomas grow slowly and may not cause symptoms at first, while others lead to noticeable changes depending on the affected nerve.
In the case of vestibular schwannoma, you may experience:
- Progressive hearing loss
- Tinnitus (ringing in the ear), which is a common early symptom
- Symptoms from tumour growth, including facial numbness, vertigo, headaches, and worsening balance or coordination due to brainstem compression or hydrocephalus
Spinal schwannomas may cause symptoms such as:
- Localised pain
- Numbness
- Tingling or musvle weakness in the limbs or trunk
- In severe cases, bowel or bladder dysfunction due to spinal cord or nerve compression
Peripheral nerve schwannomas may cause symptoms such as:
- Muscle weakness or motor deficits if they compress motor nerves
- Carpal tunnel-like symptoms if growing near a nerve in the hand or wrist
- Tarsal tunnel-like symptoms if the tumour is near the ankle
How is Schwannoma Diagnosed?
Schwannomas are usually diagnosed after symptoms are experienced or when imaging is performed for another reason. The tests used depend on where the tumour is located. Vestibular schwannoma is often diagnosed following the development of otological (hearing and balance) or neurological symptoms. Otological symptoms may include hearing loss, tinnitus, or vertigo. Neurological symptoms may include facial nerve impairment, headache, or hydrocephalus, although gradual hearing loss is far more common.
When these symptoms occur, your ENT specialist may recommend tests such as, pure tone audiometry, and MRI of the internal acoustic meatus. Because hearing loss is often the first symptom, your doctor may initially recommend an auditory brainstem response (ABR) test. However, this test is less sensitive than MRI, so abnormal or unexplained results are usually followed up with imaging.
MRI remains the gold standard test for diagnosing vestibular schwannoma, especially in patients with unexplained hearing loss, tinnitus, or balance problems.
Living with Schwannoma
Living with a schwannoma may involve adapting to issues such as one-sided hearing loss, tinnitus or balance difficulties, however this will depend on the tumour location and treatment. Although the tumour can often be treated successfully, some patients can continue to experience long-term effects. Your healthcare team may recommend vestibular rehabilitation therapy to help your brain adapt to balance changes.
Surgery can also affect overall well-being, as recovery may delay a return to normal activities or work for several weeks to a few months.. This disruption can lead to financial strain and may negatively impact mental health. For unilateral hearing loss, your healthcare team may recommend hearing devices such as hearing aids, CROS (Contralateral Routing of Signals) systems, or other assistive technologies.
Living with schwannoma can also cause significant, and often underreported, emotional distress. This may include anxiety, depression, social withdrawal, and fear of recurrence.
Support groups, such as patient advocacy organisations, and counselling can play an important role in helping individuals cope with anxiety, depression, and the stress associated with a “watch and wait” approach.
Schwannoma Treatment and Management Options
There are several approaches to treating schwannoma, including active monitoring or “watch and wait” approach, surgery, and radiotherapy. Because most schwannomas grow slowly, many people, particularly older adults or those with other medical conditions, may choose close observation with regular MRI scans. In some patients, especially those with other health conditions, surgery may carry higher risks, and observation may be a safer option.
Schwannomas associated with neurofibromatosis type 2 (NF2) often grow more quickly and are more likely to require treatment. Surgery is often recommended if the tumour is growing, causing symptoms, or compressing important structures such as the brainstem
If the tumour is in a surgically accessible location, it can often be completely or nearly completely removed. When surgery successfully removes the tumour, long-term tumour control is high, although recurrence risk varies depending on how much tumour is removed. If recurrence occurs, it may develop many years later, so long-term follow-up imaging is important.
Radiotherapy is another treatment option, particularly for smaller tumours or for patients who are not suitable candidates for surgery. The most commonly used techniques are stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT)
These highly targeted radiation approaches aim to control tumour growth while minimising damage to surrounding tissue. However, they are generally less suitable for very large tumours or those causing significant brainstem compression.
Treatment decisions are individualised and based on tumour size, growth rate, symptoms, location, overall health, and patient preference.
Disclaimer: All Cure Brain Cancer Foundation website content is created and published online for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. You should seek your own medical advice from your doctor or other qualified health professionals.
References
- Guo, S., Zheng, X., Chen, W., Raza, U., Zeng, A., Akter, F., Huang, Q., & Yao, S. (2024). From bench to bedside: Advancing towards therapeutic treatment of vestibular schwannomas. Neuro-Oncology Advances, 6(1), vdae107. https://doi.org/10.1093/noajnl/vdae107
- Gupta, V. K., Thakker, A., & Gupta, K. K. (2020, 2020/12/01). Vestibular Schwannoma: What We Know and Where We are Heading. Head and Neck Pathology, 14(4), 1058-1066. https://doi.org/10.1007/s12105-020-01155-x
- Helbing, D.-L., Schulz, A., & Morrison, H. (2020, 2020/08/01). Pathomechanisms in schwannoma development and progression. Oncogene, 39(32), 5421-5429. https://doi.org/10.1038/s41388-020-1374-5
- https://www.cancer.gov/pediatric-adult-rare-tumor/rare-tumors/rare-soft-tissue-tumors/schwannoma