Facial palsy is defined as a condition characterised by weakness in the muscles of the face. It is generally caused by damage in the facial nerve, unilaterally or bilaterally. The facial nerve innervates the facial muscles. Any trauma or damage in the facial nerve disrupts nerve conduction and thus prevents the facial muscles from receiving the necessary stimuli to function normally. This often leads to paralysis of the face. In some cases the facial palsy affects only the lower half of the face; while in other cases, it affects one whole side of the face. In some cases, paralysis of both sides has been noted.
Facial nerve supplies the face on each side separately. It originates from the brain and enters the facial area through front of the ear, where it branches out into 5 braches. The facial nerve controls the facial expression, saliva production, taste sensation, tear production etc. Central facial palsy, as formerly known as Bell's palsy, is a condition where a person experiences sudden paralysis in the facial muscles.
What is Central Facial Palsy?
Central facial palsy or Bell's palsy is a condition characterised by sudden paralysis or weakness in the facial muscles. It is caused by damage or compression of the seventh cranial nerve (or facial nerve) and thus it is also known as seventh nerve palsy. Nerve damage may be caused by inflammation or swelling of the nerve leading to abnormal functioning of the nerves. Bell's palsy was first described by a Scottish anatomist, Charles Bell and hence, the condition was named after him. Bell's palsy generally affects only one side of the face. In very rare cases, it affects both side of the face. Central facial palsy is a temporary condition and in a large no of cases, complete recovery is noted. The sudden onset of Central facial palsy is often misunderstood as onset of a stroke.
Symptoms of Central Facial Palsy
Central facial palsy is often predisposed by a viral infection. The symptoms of Central facial palsy are usually noticed 2 to 3 weeks after an episode of cold, eye infection or ear infection. The symptoms appear suddenly and may be noticed after waking up in the morning or while eating or drinking. In most of the cases, central facial palsy presents itself with a droopy appearance of the face on the affected side, often accompanied by inability to close or open the eye on the affected side.
The common signs and symptoms of Central facial palsy or Bell's palsy are as follows:
- Uncontrolled drooling
- Lope sided smile
- Lack of wrinkles on the forehead
- Difficulty in blowing air from mouth and whistling
- Difficulty with opening and closing of mouth, making it difficult to eat or drink is a symptom of Central facial palsy.
- Inability to smile, frown or make other facial expressions
- Weakness of the facial muscles
- Muscles twitches over the affected side of the face
- Dryness of eyes is also a common symptoms of Central facial palsy
- Mouth dryness
- Speech difficulties
- Loss of taste sensation
- Persistent headache
- Increased sensitivity to sound.
The symptoms of Central facial palsy are similar to those that develop in other serious conditions such as stroke or brain tumor.
Epidemiology of Central Facial Palsy
Central facial palsy can occur at any age; however, the occurrence is more frequent among individuals between the ages of 16 to 60 years. It affects both men and women equally. Studies have shown that 1 among 60 people may develop central facial palsy at some point in their life.
Prognosis of Central Facial Palsy
Central facial palsy has a good prognosis. In most of the cases, the condition does not need any active treatment and the symptoms subside on its own. The recovery time of central facial palsy depends on the extent of the nerve damage. Improvement may be noticed in 2 weeks or it may even take 3 to 6 months to normalize. In some cases, Central facial palsy lasts for a prolonged period of time and in very rare cases, the symptoms may cause permanent damage to the facial nerve, leading to permanent facial paralysis.
Causes of Central Facial Palsy
Central facial palsy is caused by swelling or compression of the seventh cranial nerve or the facial nerve which leads to paralysis or weakness of the facial muscles. The exact cause of Central facial palsy is yet unknown. A large number of researches are being carried out to study central facial palsy closely. The most accepted cause of central facial palsy or Bell's palsy at present is viral infection. The following condition has been linked to cause central facial palsy as well:
- Herpes simplex associated with genital herpes and cold sores
- HIV leading to suppression of the immune system
- Sarcoidosis or inflammation of an organ
- Herpes zoster virus (which also causes shingles and chicken pox)
- Mononucleosis caused by Epstein-Barr virus.
Pathophysiology of Central Facial Palsy
The exact pathophysiology of Central facial palsy is not known. In most of the cases, recent history of viral infection leads to irritation of the facial nerves. There is compression of the facial nerve associated with swelling and inflammation of the nerve. This in turn interferes with nerve conduction and transmission of the signals leading to loss of function of the nerves. The muscle supplied by these nerves, becomes weak and this eventually leads to paralysis of the face on the affected side.
Risk Factors of Central Facial Palsy
The risk of developing central facial palsy increases in the presence of the following conditions:
- Recent history of viral infection
- Infection in the lungs
- Known family history of facial nerve palsy.
Complications Associated with Central Facial Palsy
In most of the cases, central facial palsy recovers without any potential complications. However, in advanced cases, it can lead to serious complications. These are as follows:
- Permanent damage to the facial nerve leading to permanent paralysis of the facial muscles.
- Excessive dryness in the eyes can lead to eye infections, ulceration and if left untreated, it can even lead to blindness.
- The patient may develop synkinesis, i.e. movement of one body part leads to involuntary movement of another body part. E.g., the patient may involuntarily express a smile while closing his eyes.
- In rare cases, the condition may reoccur.
Diagnosis of Central Facial Palsy
The diagnosis and treatment of central facial palsy is done by an experienced physician or a neurologist. A detailed case history is obtained followed by clinical examination to evaluate the extent of facial weakness. The physician may ask the patient to demonstrate certain facial expressions such as smiling, frowning, raising eyebrows, closing and opening the eyes, blowing air through mouth etc. to determine the extent of the damage. Blood work may be ordered to rule out presence of bacteria, virus or other pathogens. Investigative studies such as MRI, CT scan and EMG may be performed for further evaluation and management.
Treatment of Central Facial Palsy
In most of the cases, central facial palsy does not require any specific treatment and improves on its own. It takes several weeks to months for the condition to normalize. The following treatment options may be considered for fast recovery and for symptomatic relief:
- Steroids such as corticosteroids can help in management of inflammation associated with Central facial palsy.
- Anti-viral medication for such as Valtrex is given in the presence of a viral infection.
- Over-the-counter medications such as ibuprofen and acetaminophen are given for management of pain and discomfort associated with Central facial palsy.
- Eye drops and eye patches in view of dryness of eyes.
- Placing warm, moist towel over the affected side of the face for symptomatic relief.
- Physical manipulation and massages over the face.
- Alternative therapies such as acupuncture can also be considered for treating Central facial palsy.
- In some cases, the Central facial palsy patients may develop emotional disturbances due to sudden onset of facial paralysis. In these cases, counselling by a therapist is beneficial.
- Surgical treatment may be considered for cosmetic reasons.
Central facial palsy or Bell's palsy is a condition caused by compression of the seventh cranial nerve or the facial nerve which leads to weakness in the facial muscles and paralysis. It usually affects the face unilaterally and in very rare cases, it affects the face bilaterally. It is a temporary condition and in most of the cases, the symptom subsides on its own. However, in some cases, the symptoms may take several months to years to resolve completely. The exact cause of central nerve palsy is unknown. Most of the cases are predisposed by an episode of viral infection such as herpes, shingles, chicken pox, sarcoidosis etc. The condition is treated symptomatically.