Bell's Palsy

Bell's palsy is a condition that causes sudden weakness in the muscles of the face on the side of the nerve supplying it. It occurs in any age group. In most cases it is self-limiting and significantly improves over a week. The affected side of the face appears to droop, deviation of the mouth while smiling and the eyelid doesn't close so most of the patients become susceptible to dry eyes and exposure keratopathy.

Bell's palsy is most commonly idiopathic there is no underlying cause, it is also known as acute peripheral facial nerve palsy of unknown cause. In upper motor neuron facial palsy, the weakness of the lower part of the face is very much greater than the upper part of the face. In the lower motor neuron type of Bell's palsy both the upper and lower part of the face are equally involved.

Bell's palsy can be upper motor neuron (UMN) type or lower motor neuron (LMN) type. It can occur at any age. There is no exact cause but according to the studies, it has been shown that the inflammation and the swelling of the facial supplying the facial muscles results in weakness of the affected side.

Signs and symptoms of bell's palsy usually improve within a month, and an almost full recovery is seen in about six weeks. Rarely do some people have symptoms for a longer duration. It's usually non-recurrent.

Bell's Palsy: Causes

The probable causes of the Bell's palsy include the following

• Idiopathic − most of the patients occur without any underlying cause

• Reactivation of the herpes simplex virus in the geniculate ganglion following herpes simplex virus in the geniculate ganglion

• Chickenpox and shingles (Herpes zoster)

• German measles

• Mumps virus infection

• Influenza-B causing flu

Bell's Palsy: Symptoms

The major symptoms of the bells palsy include the following

• Mild weakness to paralysis of one side of the face

• Facial droop and difficulty in making facial expressions, such as smiling, closing the eyelids

• Because of the inability to close the eyelid patient presents with symptoms of dry eyes like foreign body sensation, itching of eyes, loss of corneal lustre, and exposure keratopathy.

• Eye on the paralyzed side rolls upwards (bells phenomenon)

• Heaviness or numbness of the face

• Deviation of the mouth to the normal side while smiling

• Pain around the jaw or in or behind the ear on the affected side

• Increased sensitivity to the sound on the affected side

• A decrease in the ability to taste

• Changes in the number of tears or saliva production

• No forehead wrinkles are formed on the affected side when the forehead is raised

Bell's Palsy: Risk Factors

Bell's palsy occurs more often in −

• Pregnant women, especially during the third trimester or who are in the first week after giving birth

• People having upper respiratory tract infections, such as flu or cold.

• Diabetes and hypertension

• Patients with preceding viral infection

• Family history of Bell's palsy

Bell's Palsy: Diagnosis

• History of onset of symptoms is used to diagnose Bell's palsy

• Observation of the patient confirms the diagnosis

• Electromyography can be done; this test assesses the amount of nerve damage and its severity. It measures the electrical activity of the muscle in response to the stimulation and the nature of the speed of the conduction of the electrical impulses along the nerve

• Nerve excitability test can be done, in this minimum electrical stimulus required to produce visible muscle contraction is tested

• Trigeminal blink reflex to study the intracranial pathway

• Imaging scans like Magnetic resonance imaging or computerized tomography

• May be needed to rule out other possible causes of pressure on the nerve such as a facial tumor skull fracture.

Bell's Palsy: Treatment

Conservative Treatment includes the following

• The mainstay of the treatment is corticosteroid therapy to decrease the inflammation on the nerve, prednisolone is the most commonly given drug given in the dose of 1mg/kg/Bw/day.

• Acyclovir is given in cases of herpes infection

• Eye care to prevent dry eyes, maintenance of lubrication of the eyes with artificial tear supplements, eye patch during the night while sleeping

• Physiotherapy is beneficial in some patients to maintain muscle tone

• Electrical stimulation to maintain muscle tone

• Heat application

• Massage

• Electrical stimulation

Surgical Treatment includes the following −

• Tarsorrhaphy

• Surgical decompression

• Recently nerve transfer has also been tried

• Functional facial plastic surgeries for nonrecovery patients

Bell's Palsy: Prevention

There are no studies or no known methods to prevent the Bell's palsy. The condition which causes the immune system to decrease should be checked properly.

Diabetes, immune deficiency state, Hypertension, and previous history of viral illness should be monitored closely and proper follow-up should be done. Proper medical advice should be taken if these conditions are seen in an individual.

Conclusion

Bell's palsy is the weakness of the facial muscles caused due to damage to the seventh cranial nerve, i.e., the facial nerve. It occurs at any age, and there is no proper known cause, but the palsy is self-limiting, responds well to corticosteroids.

About 71% of the patients with bell's palsy have complete functional recovery within six months;it can be easily diagnosed and managed. One can diagnose the bells palsy based on the presentation most of the time investigations are not necessary unless indicated.

Old age, patients having hypertension, diabetes mellitus, Impairment of taste, and complete facial weakness may hinder the recovery of the patient. About 20% of the patients may have incomplete recovery and residual effect.