What is Facial Nerve Palsy?
Facial nerve weakness or paralysis is a common issue, especially treated by ear, nose, and throat doctors, but also in overall medical practice. The facial nerve is fundamental for expressing emotions and communication. When it malfunctions, the quality of life can decline significantly.
When a patient comes in with facial weakness, one of the initial steps healthcare providers take is to figure out whether the cause is linked to a lower motor neuron (LMN) or an upper motor neuron (UMN) – these are two types of nerve cells that help control muscle activities. The treatment strategies for these two types of facial weakness can differ greatly. By connecting knowledge of the body’s anatomy with the patient’s history and physical exam, healthcare providers can identify the most likely cause of the facial nerve weakness and design a fitting treatment plan.
What Causes Facial Nerve Palsy?
When one side of your face suddenly becomes weak or paralysed, it may be due to a condition known as facial nerve palsy, commonly known as Bell’s Palsy. The exact reason for this is often unknown, hence the term ‘idiopathic’. It usually takes effect within the first 24 to 48 hours and can take up to one year to fully recover. In some cases, around 13%, complete recovery may not be achieved.
Physical injury is another cause, accounting for 10 to 23% of facial nerve palsy cases. For instance, a wound or fracture to certain areas of the face or skull can cause facial nerve palsy. These fractures are often accompanied by signs like bleeding from the ear or issues with balance and coordination.
Infections, both viral and bacterial, can also lead to this condition. One of the viruses that can potentially cause facial nerve palsy is the Herpes Zoster virus, which also causes a condition known as Ramsay Hunt syndrome. Patients with this condition may experience ear pain, skin eruptions, and sometimes dizziness due to the virus’s effect on the ear’s nerves. Bacterial infections, on the other hand, can lead to nerve paralysis by causing complications in the ear or due to a rare condition known as Lyme disease, which is transmitted by tick bites.
A slowly progressing onset of facial nerve palsy may be a sign of a tumor. These can be caused by a variety of cancers. A thorough examination of the head and neck is required when such a suspicion arises.
In children, facial nerve palsy can either be due to the same causes as adults or due to conditions present at birth. Certain factors during birth, such as a high birth weight, use of forceps, prematurity, or cesarean section, may lead to this condition. Certain genetic factors or syndromes can also be the cause. Surgery isn’t usually recommended for children due to the risk of hearing loss but nerve grafts and muscle transfer techniques may be considered.
In rare cases, facial nerve palsy can affect both sides of the face. This is a sign of a more serious systemic disease, with Lyme disease being a common cause. Other causes could include conditions like Guillain-Barre syndrome, diabetes, Parkinson’s disease, multiple sclerosis, and other neurological conditions.
Risk Factors and Frequency for Facial Nerve Palsy
Most of the time, facial nerve palsies occur without a known cause. However, healthcare professionals need to ensure that it’s not a result of a brain stroke or any other serious health issue. There is no evidence to suggest that certain genders, races, or age groups are more prone to this condition. However, it is commonly seen in people aged 15 to 45.
Within the different types of facial nerve palsies, Bell palsy is the most common, making up around 70% of all cases. Other causes include injury, which contributes to between 10 and 23% of cases, viral infections responsible for 4.5 to 7% of cases, and tumors constituting between 2.2 to 5%.
- Facial nerve palsies mostly occur without a known cause.
- But, it’s important to rule out serious problems like brain stroke.
- It affects all genders, races, and ages, but is common in those aged 15 to 45.
- Bell palsy is the most common type of facial nerve palsy, making up 70% of cases.
- Injury is the next most common cause, contributing to 10 to 23% of cases.
- Then comes viral infections, causing 4.5 to 7% of facial nerve palsies.
- The least common cause is tumors, contributing to 2.2% to 5% of cases.
Signs and Symptoms of Facial Nerve Palsy
When a patient shows signs of facial nerve palsy after a viral episode, there could be a number of causes, including Bell’s Palsy or Ramsay Hunt Syndrome (RHS). Specific symptoms, such as blisters, can help determine the cause. Asking about any ear discomfort or hearing changes could indicate issues such as ear infections or conditions like acoustic neuroma or cholesteatoma. A neurological history is also useful in understanding a facial nerve issue.
Testing the facial movements can determine if an issue is in the upper part of the motor neuron, which would mean the forehead isn’t affected, or the lower, where all facial movements might be compromised. The severity of the nerve paralysis is often graded using the House-Brackman system, which ranges from grade I, indicating normal function, to grade VI, suggesting complete lack of movement.
- Grade I – Normal symmetrical function throughout
- Grade II – Slight weakness visible upon close inspection and slight asymmetry of smile
- Grade III – Obvious non-disfiguring weakness, complete eye closure
- Grade IV – Obvious disfiguring weakness, inability to lift eyebrow, incomplete eye closure, severe synkinesis
- Grade V – Barely perceptible motion, incomplete eye closure, slight movement of corner of mouth, absent synkinesis
- Grade VI – No movement, atonic (loss of muscle tone)
The main difference between grades III and IV is the ability to close the eye.
Several tests can be used to clinically evaluate the facial nerve lesion such as:
- Blink test (corneal reflex) – a cessation in blinking on the affected side following a tap on the forehead
- Schirmer test (assessing tear creation) – may reveal a decrease in tearing by 75% compared to the normal side
- Stapedial test – checks the reflex of a small muscle in the ear in response to loud sounds
- Salivary Test – assesses the rate of salivation following stimulation with a 6% citric acid solution. A positive result shows a 25% reduction in saliva production on the affected side
- Taste test – investigates the taste sensation on the tongue. An issue may indicate a nerve root lesion
Additional checks on the external ear, parotid (salivary) gland, oral cavity, and eye may reveal other relevant health conditions such as otitis, various ear infections, vesicles suggestive of Ramsay-Hunt syndrome, parapharyngeal masses, vesicular eruptions, or eye closure issues. If the eye isn’t closing fully, it’s vital to consult an ophthalmologist and use eye protection.
Testing for Facial Nerve Palsy
If you come to the hospital with facial palsy, which is when part of your face appears droopy, the cause might be an infection. So, you’ll need some blood tests to help your doctor find out what’s causing the problem. These might include a complete blood count (which measures different types of cells in your blood), a urea and electrolytes test (which checks how well your kidneys are working), and a C-reactive protein test (which can indicate if inflammation is happening in your body).
In some particular cases like Ramsey Hunt Syndrome or Lyme disease, blood tests can help identify certain viruses or bacteria. For example, if the varicella-zoster virus is causing an infection, it will cause a rise in antibodies that fight this virus in your blood. Similarly, if Lyme disease is suspected, certain proteins called IgG and IgM will increase.
Besides blood tests, you might need to undergo some special tests. An audiogram can help in assessing whether you have any hearing loss and how severe it is. There are also some in-depth nerve tests that can be done: electrophysiological tests, and electromyography (EMG). These studies involve stimulating your facial nerves and muscles and recording their responses, but they tend to be costly and time-consuming.
Another test involves using magnetic fields to stimulate parts of your facial nerve. That said, this test needs to be done quickly once your symptoms start because the health of your nerve can change fast over time.
Finally, depending on your symptoms, your doctor might ask for imaging tests. These might be a CT scan or an MRI. CT scans are usually requested if there’s a suspicion that an ear infection could be the cause of the problem, or if you’ve had a head trauma or if your doctor thinks there could be cancer. MRI scans are very good at showing parts of the body in high detail, and can help find anything abnormal putting pressure on the facial nerve. MRI scans can also show if there is any swelling along the facial nerve.
Treatment Options for Facial Nerve Palsy
It’s essential to take care of your eyes if you have facial muscle weakness that leads to constant exposure of your eyes. This can be done by using artificial tears, ensuring your eyes are properly lubricated, and taping your eyes closed at night. These measures help prevent damage to the cornea, the clear layer at the front of your eye. A check-up with an eye doctor may also be suggested.
Facial massages and exercises are also crucial in speeding up recovery and rehabilitating facial muscles in individuals with facial nerve palsy.
If you have Bell’s palsy, which is a condition that causes sudden, temporary weakness in your facial muscles, medicine such as steroids and pain relievers may help speed up recovery. This is most effective when started within 72 hours of when the symptoms first appear. Research suggests that over 70% of patients with Bell’s palsy will fully recover within six months even without treatment.
For Ramsay Hunt syndrome, which is a complication of shingles marked by pain and a rash in or around your ear, doctors often use a similar approach, adding an antiviral medicine to help fight the viral infection. Generally, three in four patients are expected to recover facial nerve function with full treatment. It’s worthy to note, however, that the benefits of using antiviral therapy in this context are not yet fully proven.
If you have Lyme disease, the treatment plan will depend on your age and how severe the disease is. Usually, you will be prescribed an antibiotic such as doxycycline, amoxicillin, or cefuroxime depending on your age to avoid potential side effects. For most early and localized cases, treatment is usually curative.
In some severe cases of Bell’s palsy where the nerve damage is on an extremely high level, surgery to relieve pressure on the facial nerve may be considered, although this approach hasn’t shown significantly better outcomes compared to traditional medical treatments.
If you develop facial nerve palsy after surgery, your doctor might recommend waiting for a while to see if the palsy might be due to the anesthesia used during the surgery. If facial nerve damage is suspected and it’s clear the facial nerve sheath is still intact, a conservative approach with steroids can be used. If not, urgent corrective surgery may be needed.
In the event of a temporal bone fracture that causes immediate and complete facial nerve paralysis, specialist nerve decompression is required as soon as the patient’s condition allows. If a severe degree of nerve damage is detected after a delayed diagnosis, surgical exploration is required.
Lastly, if facial nerve palsy becomes long-term (more than two years), a muscle transfer procedure may be appropriate. Muscles commonly used for this procedure include the temporalis muscle (near the temples), the digastric (lower jaw), and the masseter (jaw). These surgeries aim to restore facial symmetry and function, like smiling.
Another promising treatment option for those with unilateral facial nerve palsy is transcutaneous nerve stimulation. This is a kind of therapy that uses signals from muscles on the healthier side of the face to stimulate the muscles on the affected side. The goal is to achieve symmetry in your facial expressions. Early trials have shown positive results in significantly improving facial expressions in affected areas.
What else can Facial Nerve Palsy be?
When doctors try to figure out the cause of facial nerve palsy, the most crucial factor is identifying whether the problem is related to a lower motor neuron (LMN) or an upper motor neuron (UMN).
Only lower motor neuron conditions result in full facial paralysis because both sides of the brain control the upper facial muscles. However, this isn’t always the case. One important way for doctors to determine if it’s an upper or lower motor neuron issue is by a facial movement test – assessing the ability to raise eyebrows.
Different conditions can lead to problems with the lower or upper motor neurons. Here is a list of conditions associated with each type:
- Lower motor neuronal lesions: These could include conditions like Bell’s palsy, Ramsay Hunt syndrome, among others.
- Upper motor neuronal lesions: These could include conditions like strokes, multiple sclerosis, bleeding beneath the dural membrane of the brain (subdural hemorrhage), or brain tumors (intracranial neoplasia).
What to expect with Facial Nerve Palsy
The outcome of a facial nerve palsy, a condition where you lose normal control of facial muscles, may not be favorable if certain factors are present. These include:
– Complete palsy: This means total loss of muscle function in the face.
– Loss of the stapedial reflex: This is a reaction that protects your ear from loud noises. If it’s lost, it could suggest more serious nerve damage.
– No signs of recovery within three weeks: If there are no improvements in this time frame, it could indicate a more serious condition.
– Age over 50 years: Older people may have a harder time recovering from this condition.
– Ramsay Hunt syndrome: This is a condition where a facial nerve is affected by a viral infection. It can make the recovery more difficult.
– Poor response to electrophysiological testing: Electrophysiological tests measure nerve function. A poor response could suggest more severe nerve damage.
Possible Complications When Diagnosed with Facial Nerve Palsy
Facial nerve palsy, a condition causing one-sided facial weakness, can lead to a range of complications that significantly affect a patient’s life. Mainly, these complications include eye issues, involuntary facial movements, facial asymmetry, and linked movements.
Eye problems occur when the facial nerve isn’t functioning correctly. Patients can experience keratitis, a condition where the cornea dries out and might form ulcers. As a preventive measure, consistent eye care is emphasized to minimize these risks.
Other complications include:
- Hemifacial spasm: This occurs when the facial nerve undergoes damage, causing uncontrolled contractions on one side of the face.
- Facial asymmetry: This abnormality leads to a noticeable difference between both sides of the face and can cause significant distress due to the physical alteration.
- Synkinesis: This condition results in unintended movements during voluntary facial actions. Common examples are the unintended movement of the mouth when closing the eye or “crocodile tear syndrome,” where one sheds tears while eating.
Doctors manage these complications through facial muscle therapy and botulinum toxin treatment. The therapy aims to strengthen the weaker side of the face to compensate for involuntary movements. Meanwhile, botulinum toxin is used to induce temporary muscle paralysis, effectively managing conditions like synkinesis and hemifacial spasm.
Preventing Facial Nerve Palsy
People suffering from facial nerve palsy, or the weakness of the muscles in the face, often have to face a different set of problems. Educating these patients can greatly help in reducing potential complications and guiding them in how to manage their daily lives. For example, patients may need to learn ways to handle dryness in eyes and mouth, how to safely close an eye with tape to avoid scratches or sores on the cornea (clear front surface of the eye), adapting their eating and drinking, getting used to changes in facial expressions, and making adjustments to speech and language (especially for children in the developmental stages).
Offering patients comprehensive guides and educational materials on dealing with these issues can significantly improve their quality of life and overall health progress. This information can also be helpful to the patient’s family and friends who may want to understand how to best assist someone dealing with facial nerve palsy. Moreover, some patients find strength in numbers and appreciate connecting with charities and support groups. Interacting with others facing similar challenges allows them to share ideas and strategies for managing their condition.
