What is facial nerve neuropathy?
Facial nerve neuropathy is weakness or paralysis of the muscles on one side of the face caused by damage to the nerve that controls the muscles of facial expression. Its most common form is Bell’s palsy, which starts suddenly and has no clear cause.
Among the neuropathies of the cranial nerves, facial nerve neuropathy is one of the most common conditions. The facial nerve starts in the brainstem and passes through a narrow canal inside the skull to reach the facial muscles. As well as facial expression, it is involved in producing tears and saliva, in taste on the front part of the tongue and in regulating sensitivity to sound.
How do the central and peripheral types differ?
Facial palsy can be central (due to damage in the brain) or peripheral (due to damage to the nerve itself). This distinction is very important for diagnosis.
- Peripheral type — more common. On the affected side the forehead cannot be wrinkled, the eyelid does not close fully, the cheek cannot be puffed out, the corner of the mouth droops and smiling becomes difficult.
- Central type — the damage is in the brain (for example, a stroke). There is weakness in the lower part of the face, while forehead movements are usually preserved.
What are the causes and risk factors?
The most common cause of peripheral facial palsy is Bell’s palsy: it is explained by compression of the nerve in the narrow canal due to inflammation and swelling, and is often linked to a viral infection. Other causes include the following.
- Ramsay Hunt syndrome (shingles virus in the ear area)
- Lyme disease and other infections
- Complications of middle ear infection
- Head and facial injuries
- Tumours (for example, tumours of the parotid gland or the base of the skull)
- Congenital conditions such as Moebius syndrome
Diabetes, high blood pressure, pregnancy and upper respiratory tract infections are noted as factors that increase the risk of Bell’s palsy.
What are the symptoms?
In Bell’s palsy the symptoms usually develop rapidly over one or two days.
- Drooping of one side of the face, a lopsided mouth when smiling
- The eyelid not closing fully, a dry or, conversely, watery eye
- Water or food spilling from the mouth
- Pain behind or around the ear
- Changes in taste on the front part of the tongue
- Sounds seeming excessively loud
Signs pointing to another cause
The following are not typical of Bell’s palsy and require further investigation.
- Weakness or reduced sensation in an arm or leg
- Cerebellar signs, involvement of other cranial nerves, facial palsy on both sides
- Widespread and severe facial pain beyond the area around the ear, loss of sensation in the face
- A blistering rash in the ear or mouth
- Weakness that gradually increases over weeks
When is emergency help needed?
If sudden drooping of one side of the face is accompanied by weakness in an arm or leg or speech problems, it may be a sign of stroke — in that case call 103 immediately. Read more: The first signs of stroke — BE FAST. Even if there is facial palsy alone, you should see a doctor the same day, because treatment is more effective when started early.
How is it diagnosed?
The diagnosis is mainly based on a detailed neurological examination: the doctor checks whether the palsy is peripheral or central, whether other nerves are affected, and looks for ear and skin signs. In typical Bell’s palsy, further tests are often not needed. In doubtful cases, blood tests (for example, for diabetes or infections), an MRI or a CT scan may be ordered. In some cases EMG (electroneuromyography) is carried out to assess the degree of nerve damage and the prospects for recovery.
What do treatment and recovery involve?
In most patients with Bell’s palsy, movement of the facial muscles starts to improve within a few weeks and often recovers within a few months. The main factor that helps recovery is early assessment and treatment: corticosteroid treatment is more effective when started within the first 72 hours, and the decision to prescribe it is made by the doctor. In some cases the doctor may also prescribe an antiviral medicine.
When the eyelid does not close fully, it is important to protect the eye from drying out and injury (moisturising drops, an eye patch at night). In suitable cases, physiotherapy and facial muscle exercises support recovery. If the symptoms do not improve within a few months, a repeat neurological examination is needed to re-investigate the cause. In neuropathies arising from other causes, treatment is directed at the underlying condition.
What should I pay attention to in everyday life?
- Protect the eye from wind and dust, and use moisturising drops during the day.
- Chew food on the healthy side and eat in small bites.
- Do the facial exercises recommended by your doctor or physiotherapist in front of a mirror.
- Keep your diabetes and blood pressure under control.
Frequently asked questions
Is Bell’s palsy a stroke?
No, Bell’s palsy is damage to the nerve itself. However, because facial drooping also occurs in stroke, stroke must be ruled out, especially if there are other symptoms.
Does facial palsy go away completely?
Most people with Bell’s palsy recover completely or almost completely within a few months. Some may have mild residual symptoms.
Does cold wind cause facial palsy?
Cold wind has not been proven to be a direct cause. Bell’s palsy is more often linked to inflammation of the nerve and viral infection.
Can Bell’s palsy come back?
In rare cases it can recur. If facial palsy recurs or affects both sides, further investigation is carried out to rule out other causes.