Schwannoma (Trigeminal & Acoustic)
What is a Schwannoma?
Schwannomas are relatively rare benign skull base tumors that arise from the nerve sheath (covering) of cranial nerves along-side the cerebellum and brainstem. The two most common are the vestibular schwannoma (also known as acoustic neuroma) of the 8th cranial nerve and the trigeminal schwannoma of the 5th cranial nerve.
Schwannomas can occur anywhere in the body, but they most commonly develop in the head and neck region, particularly in the vestibular nerve, which is responsible for balance and hearing. Schwannomas that develop in the vestibular nerve are known as vestibular schwannomas, or acoustic neuromas. These tumors can cause symptoms such as hearing loss, ringing in the ears (tinnitus), dizziness, and balance problems.
Minimally invasive keyhole & endoscopic surgery is now possible for most symptomatic schwannomas.
Vestibular schwannomas (acoustic neuromas)
Vestibular schwannomas or acoustic neuromas are the most common and typically cause hearing loss and ringing in the ears (tinnitus); as they enlarge they may also cause imbalance and incoordination as well as facial weakness.
Trigeminal schwannomas
Trigeminal schwannomas are less common and typically case facial numbness, tingling or facial pain.
The most common schwannoma arises from the 8th cranial nerve (the vestibulo-cochlear nerve) or the 5th cranial nerve (the trigeminal nerve). In some instances, schwannomas are related to a genetic syndrome called Neurofibromatosis. Bilateral vestibular schwannomas are associated with NF-2.
Types of Schwannomas
The two most common are the vestibular schwannoma (acoustic neuroma) of the 8th cranial nerve and the trigeminal schwannoma of the 5th cranial nerve.
Vestibular schwannomas (Acoustic neuroma)
Vestibular Schwannomas are the most common and typically cause hearing loss and ringing in the ears (tinnitus); as they enlarge they may also cause imbalance and incoordination as well as facial weakness.
Trigeminal schwannomas
Trigeminal schwannomas are less common and typically case facial numbness, tingling or facial pain.
Symptoms of Schwannomas
Vestibular schwannoma (acoustic neuroma) symptoms
Vestibular schwannomas (acoustic neuromas) arise from one of the vestibular nerves in the internal auditory canal and initially cause hearing loss and tinnitus (ringing in the ear).
As they enlarge into the cerebello-pontine angle, they can compress the brainstem and other cranial nerves, resulting in:
- Loss of balance and coordination
- Vertigo
- Facial numbness
- Facial weakness
- Difficulty swallowing
Trigeminal schwannoma symptoms
Trigeminal schwannomas are less common than vestibular schwannomas. They generally arise in Meckel’s cave in the skull base and the pre-pontine space.
- Facial pain (trigeminal neuralgia) or facial numbness
As they enlarge, they can grow farther into the cavernous sinus or into the brainstem, causing:
- Double vision
- Loss of coordination
- Other symptoms of brainstem compression
Schwannomas are typically diagnosed by an MRI with gadolinium or a CT scan of the brain. A focused MRI of the internal auditory canals is typically best for visualizing a vestibular schwannoma.
Other tests may also be needed such as:
- Angiography (typically now performed as a CT angiogram or an MR angiogram)
- Audiograms
Schwannoma Treatment
The optimal treatment for the majority of symptomatic vestibular and trigeminal schwannomas is maximal safe surgical removal. For patients with smaller vestibular schwannomas focused radiation therapy (radiosurgery) may be a reasonable option instead of surgery.
Fortunately, for patients requiring schwannoma surgery, most large acoustic neuromas can be removed through a retromastoid (behind the ear) keyhole craniotomy while most trigeminal schwannomas can be removed through either a retromastoid approach or an endoscopic endonasal approach.
Vestibular schwannoma (acoustic neuroma) treatment
Treatment for vestibular schwannomas (acoustic neuroma) is by surgical removal through a keyhole retrosigmoid craniotomy or other skull base approach or by radiosurgery.
For tumors under 2.5 cm, either surgery or radiosurgery are reasonable treatment options. For tumors over 2.5 cm, surgical removal is generally recommended.
Trigeminal schwannoma treatment
Treatment for trigeminal schwannomas is typically by surgical removal through a retrosigmoid craniotomy or other skull base approach, depending upon the location.
In some patients with a vestibular or trigeminal schwannoma in whom only a sub-total tumor removal is possible, radiosurgery or stereotactic radiotherapy may be effectively used to control further tumor growth.
Chemotherapy is generally not used for treating schwannomas.
Is schwannoma serious?
Some schwannomas can grow very large and cause major brain / brainstem compression which could affect major neuroogical problems over time.
What are the symptoms of a schwannoma?
Cranial schwannomas include vestibular schwannomas, trigeminal schwannomas and facial schwannomas.
Vestibular schwannomas (acoustic neuromas) can cause hearing loss, facial numbness, pain or weakness, headaches, imbalance, swallowing difficulties and weakness.
Trigeminal schwannomas can cause facial numbness, imbalance, weakness, headaches, and hearing loss.
Facial nerve schwannomas can cause facial weakness, hearing loss or imbalance.
How is schwannoma treated?
Large schwannomas are treated with surgical resection. small schwannomas can be treated with surgery or stereotactic radiosurgery, though some can be observed to see if they may grow or cause neurological deficits.
Are schwannoma tumors painful?
Some can cause headaches and/or facial pain.
Can schwannomas spread?
No, schwannomas don’t spread.
How is schwannoma diagnosed?
MRI and audiogram.
How do you treat a nerve sheath tumor?
A nerve sheath tumor is treated by surgical resection (removal).
Is schwannoma benign?
Yes, most often schwannomas are benign (noncancerous).
Is schwannoma a brain tumor?
Yes, schwannoma is considered a brain tumor.
Are schwannoma tumors cancerous?
Schwannoma tumors are not cancerous.
Can schwannoma cause facial paralysis?
Yes, vestibular schwannona (acoustic neuroma) patients are at risk for facial nerve paralysis. Factors include size of tumor, location, and growth rate. Some patients may develop facial paralysis prior to diagnosis/treatment due to compression of the facial nerve. If the facial nerve is injured as a result of removal of the acoustic neuroma, patients may experience facial paralysis after surgery and it is essential to consult a facial reanimation expert immediately and create a plan to manage the paralysis.
Doctors and Specialists Who Treat Schwannoma & Acoustic Neuroma
At Pacific Brain Tumor Center, our neurosurgeons have a large experience treating such skull base tumors with keyhole and endoscopic approaches. By incorporating leading-edge technology and instrumentation with proven surgical experience, our specialists strive to make schwannoma / acoustic neuroma surgery safer, less invasive and more effective.
Patient Support
The Acoustic Neuroma Association (ANA) provides nationwide resources for patients and their loved ones.
