Table of Content:
- What is Bell’s Palsy?
- Risk Factors & Complications
- How is it Diagnosed?
What is Bell’s Palsy?
Bell’s palsy is also known as acute peripheral facial palsy of unknown cause and is a condition that can occur at any age. It is characterized by the sudden weakness of facial muscles on one side which causes one half of your face to droop. Your eye on that side resists closing and your smile appears one-sided. The exact cause is still unknown, though a few theories exist. Bell’s palsy was named after the anatomist Charles Bell who first described the condition.
Causes of Bell’s palsy
Bell’s palsy is believed to be the result of inflammation and swelling of the facial nerve that supplies the muscles on one side of your face. Viral infections that are associated with Bell’s palsy include:
- Herpes zoster, which causes chickenpox and shingles
- Infectious mononucleosis
- Adenovirus that is associated with respiratory illnesses
- German measles causing Rubella virus
Symptoms of Bell’s palsy
As a result of the inflammation of the facial nerve, there is compression of the nerve when it passes through a narrow tunnel in the facial bones, leading to a loss of function of the muscles on one side of the face as well as the lack of production of saliva on the affected side.
The symptoms of facial palsy that may appear all of a sudden are:
- Rapid onset of mild weakness or total paralysis of one side of the face, occurring within hours or days
- Facial droop. Drooping of one side of the face can occur, making it difficult to make facial expressions, smile, or close your eye on the affected side.
- Pain in the jaw or behind the ear on one side.
- Increased sensitivity to sound on one side
- Loss of taste
- Reduction in the amount of saliva produced
Rarely, Bell’s palsy may affect the nerves on both sides of the face.
Risk Factors & Complications
Those who are at an increased risk of getting Bell’s palsy include pregnant women, diabetics, and those with an upper respiratory tract infection.
Bell’s palsy is usually mild. However, there can be complications in some severe cases such as:
- Irreversible damage to the nerve fibres, leading to permanent loss of function on the affected side.
- Abnormal regeneration of the facial nerve fibres, leading to involuntary contraction of one group of muscles when you are trying to move another group. This is referred to as synkinesis. For example, when you try to smile, one eye may close without you intending to.
- Partial or complete blindness due to the inability to close the affected eye, which causes dryness and damage to the cornea.
What is the difference between facial palsy and Bell’s palsy?
Facial palsy refers to the paralysis of the facial nerve or simply facial paralysis. It can be due to a number of causes, some of which include tumours, stroke, The causes of facial palsy are divided into two categories:
- Upper motor neuron palsy or UMN palsy: This presents with forehead sparing, and is due to causes such as a stroke, a subdural hematoma, or a brain tumour.
- Lower motor neuron palsy or LMN palsy: This is mostly due to infective causes such as acute otitis media, or viral infections like CMV or EBV. Other causes include tumours and trauma.
Bell’s palsy is a type of LMN facial palsy that is idiopathic, meaning its cause is unknown and is a diagnosis of exclusion.
How is Bell’s Palsy Diagnosed?
A treating physician diagnoses Bell’s palsy after an examination of the face and obtaining a detailed history about the onset and whether there was a precedence of a viral infection.
You will be asked to move your facial muscles by doing activities such as lifting your eyebrows, smiling, frowning, and showing your teeth.
It is important to rule out other causes such as a stroke, Lyme’s disease, or a tumour. Other tests that help in confirmation of the diagnosis are:
- Nerve Conduction studty. An NCS detects the ability of a muscle to contract in the presence of an electric stimulus, and the nature and the speed of conduction of these signals. This helps to confirm nerve damage and also its severity.
- Imaging studies. A CT (computed tomography) scan, or an MRI (Magnetic Resonance Imaging) scan helps to rule out the presence of any tumours or fractures in the skull, that could present in a similar manner.
Treatment of Bell’s palsy
Physician may recommend medicines or physiotherapy to speed up the recovery process.
- Medical treatment of Bell’s palsy.
- These act by reducing inflammation and swelling of the facial nerve, thus preventing the compression symptoms.
- Though their effectiveness in Bell’s palsy is still unclear, antivirals given in addition to steroids have been beneficial for some people.
- Physical therapy for Bell’s palsy. Once paralysed, facial muscles may undergo permanent contracture. A physiotherapist can train you to massage and exercise your facial muscles to prevent shrinking or shortening.
- Plastic surgery. Facial reanimation surgery is sometimes performed to restore facial movement. This includes procedures like an eyebrow lift, eyelid lift, facial implants, and nerve grafts.
- Eye care to prevent dryness.
Dr. Vikram Huded | Senior Consultant – Neurology | Mazumdar Shaw Medical Center, Bangalore