What is a facial nerve tumour?
It is important to remember that facial nerve tumours are extremely rare; they can be mistaken for tumours that grow on the acoustic nerve called vestibular schwannomas. The most common types of tumours or growths forming on the facial nerve are schwannomas and haemangiomas.
- A facial nerve schwannoma is a growth made of Schwann cells which form part of the insulating sheath around the nerve.
- A facial nerve haemangioma is a growth made of blood vessels.
Facial nerve tumours are almost always benign, which means they are not cancerous; however there is the very low possibility of a metastatic deposit of another malignant tumour along the facial nerve (spread of an existing cancerous disease). Despite being mostly benign, facial schwannomas can still cause problems.
What are the symptoms of a facial nerve tumour?
Symptoms will vary according to the location of the tumour along the length of the facial nerve. Some tumours may develop within the parotid gland (salivary gland in the cheek), others may develop further back and present with slightly different symptoms. Below is a short list of possible symptoms:
- Facial twitching
- Slow development of a facial weakness over a period of weeks
- Hearing loss and/or tinnitus may be present depending on the location of the tumour
- Dizziness or balance problems
- Recurring one-sided facial weakness which gets better and then returns
Please note that some people may have very little, by way of symptoms, to report.
How is a facial nerve tumour diagnosed?
Due to the fact that facial nerve tumours of any kind are very rare they are often misdiagnosed. It is very important to get an accurate diagnosis, which is often radiological. The following may be used in the diagnosis of a facial nerve tumour:
- The patient’s history about the onset of their symptoms is most helpful in directing further investigations.
- The GP or doctor should observe for weakness of the facial muscles on one side of the face.
- Observations of the facial muscles should be made with the face at rest and during movements including eye closure and blinking. It is useful to have medical photographs.
- Hearing tests should be carried out if there is any suspicion that the diagnosis is a facial nerve tumour, even when there is no reported hearing loss.
- Physical examination of the face and neck to exclude the presence of any tumours that may be easily felt or seen, especially salivary gland tumours.
- A history of little or no recovery of facial weakness after several months.
- Recurrent episodes of facial paralysis or weakness should alert the clinician to a possible diagnosis of a facial nerve tumour, although there are also rare syndromes that may cause recurrent facial nerve weakness.
What investigations can be carried out to help make a diagnosis?
- CT scan of the head.
- Gadolinium-enhanced magnetic resonance imaging (MRI) of the head. Gadolinium is a contrast agent which makes it easier to see the internal structures of the body and can identify very small abnormalities. Gadolinium is usually given to the patient by injecting it directly into the bloodstream. This clearly outlines all the soft tissues such as nerves and can provide very specific information about the health of the facial nerve.
- As tumours can grow on any part of the facial nerve, all investigations should include the whole length of the nerve rather than sections.
- Electrical testing of the facial nerve.
What is the treatment for a facial nerve tumour?
The treatment will depend on the location, the size of the tumour and the severity of the facial nerve weakness. The surgeon will also take into account the patient’s age, level of fitness and severity of symptoms before deciding on the best course of action. These tumours may be managed non-operatively because surgery carries risks which can make the facial weakness worse. It will depend on the individual circumstances.
- If the symptoms are very mild, then the clinician may suggest monitoring the facial nerve regularly using MRI. Facial nerve tumours are often very slow-growing and may only cause mild symptoms, if any, throughout a person’s life.
- If the patient’s facial weakness is more obvious, then surgical removal of the tumour is usually recommended. It is often easier to preserve the facial nerve if the tumour has not grown too big. The facial nerves control all facial movement and function. There is one on the left side which operates the left side of the face and one on the right side which operates the right side of the face. It is important that the nerve is not damaged during the process of removing the tumour.
- Surgeons are aware that damaging the facial nerve can happen and may try and repair the nerve at the same time as removing the tumour; there are various surgical techniques which are used.
- More recently, radiation treatment has been used in the management of facial nerve tumours. However, because these tumours are so rare, there is very little research to support the arguments for or against this treatment approach. For small lesions, stereotactic radiotherapy may be a consideration.
What are the complications of surgery for facial nerve tumour?
The risks or complications of surgery should be discussed with your surgeon. The risks will depend on the type of tumour, its size and location along the nerve. These three factors will influence the type of surgery carried out and the individual risks associated with your particular surgery.
If you have a facial weakness prior to surgery, then it is unlikely that this will improve after surgery. In some instances it could become worse.
Below is a general list of possible risks or complications of surgery to the facial nerve:
- One of the major risks is damage to the facial nerve, resulting in weakness or paralysis of the affected side of the face. If the facial nerve has been preserved, then facial function should return, although not completely.
- If in extreme circumstances the facial nerve has been cut or sacrificed, a permanent facial paralysis will result, and the facial nerve function will come back to a grade III at best. (The House-Brackmann scale used to rate the degree of facial function has six grades, from I for normal function to VI for complete paralysis.) When this happens the patient will potentially require further treatment with the facial reanimation team who will be able to discuss the range of surgical procedures which can help restore facial symmetry at rest. There are also a range of surgical procedures that may make a small smile possible and help with eye closure.
- Meningitis (inflammation of the layers covering the brain)
- Hearing loss
- Bruising (haematoma)
Facial nerve schwannoma
Sam J. Marzo, Chad A. Zender and John P. Leonetti
Current Opinion in Otolaryngology & Head and Neck Surgery 2009, 17:000–000
Last reviewed: 20-07-2017 || Next review due: 20-07-2020