Bell’s palsy is a condition characterized by idiopathic paralysis of the facial muscles. It is caused due to the damage or compression of the facial nerve. This condition is of sudden onset and can be classified as unilateral lower motor neuron paralysis. It is not related to any other disease elsewhere in the body. This condition is also called facial palsy.
Bell’s palsy was named after Sir Charles Bell who was known for his studies related to the facial nerve. The facial nerve is the 7th cranial nerve in the humans, which controls the functions of facial muscles, eye muscles, lacrimation, salivation, taste buds of the anterior 2/3rd of the tongue, and the stapedius muscle of the ear. Facial nerve comes out from the skull through a bony canal called stylomastoid foramen to branch out and supply the various parts of the face.
Bell’s Palsy Causes
By definition, Bell’s palsy is characterized by idiopathic paralysis of facial muscles. The term ‘idiopathic’ refers to a condition or a disease which occurs spontaneously and has no definite cause.
However, there are several factors which may solely or in combination with other factors may cause inflammation of the facial nerve causing the compression on the nerve resulting in paralysis of the affected side of the face. This usually happens at a point where the facial nerve comes out of the skull. Sometimes it may also be caused due to a tumor in the brain causing nerve compression which in most cases will have associated generalized symptoms in the body.
Other factors which may cause Bell’s palsy are
- Reactivation of Herpes simplex virus, like in Ramsay hunt syndrome which is a condition characterized by the combination of facial palsy and herpes zoster infection.
- Lyme’s disease
- Migraine headaches
- Diabetes mellitus
- Chronic ear infections
- Conditions causing ischemia like extreme cold, trauma, anoxia, CO2 excess.
- Autoimmune response
- Hereditary factors
Bell’s palsy can affect people of any age group, but a higher occurrence rate has been observed in middle-aged individuals. Around 15-40 among 100,000 people are affected by facial palsy. It is more commonly seen in people who have diabetes and also pregnant women(mostly in the last trimester of pregnancy or first week of postpartum). Bell’s palsy can affect either right or left side as it is unilateral. There are very rare cases(1%) with bilateral facial palsy.
Clinical Features of Facial Palsy
Facial palsy is acute and of sudden onset. Some individuals, however, may experience pain behind the ear one or two days before paralysis. The paralysis gradually worsens in 2-3 days.
The palsy affects the unilateral side of the face with the loss of muscle control over that side. The affected side becomes stiff and face gets pulled to one side. There may be an inability to close the eyes on the affected side.
In the case of Bell’s palsy, when the affected individual makes an attempt to close the eye, the eyeball rolls upwards and inwards displaying only the white sclera of the eye. This is called Bell’s sign. Due to the inability to close the eyelids on the affected side, the eye begins to water and the lower eyelid sags down.
The corner of the mouth droops down, with saliva drooling through that side. The functions of the face that depend on the muscular actions like smiling, frowning, raising the eyebrows and whistling may become very limited.
The person having Bell’s palsy may find it difficult to eat. The food items ted to get accumulated within the folds of the cheek. There may also be a loss of taste sensation in the anterior ⅔ rd of the tongue which is supplied by the facial nerve. In some cases, facial palsy may be associated with the distortion of sound.
How to Diagnose Bell’s Palsy?
There are no specific tests suggested for Bell’s palsy. However, the doctor may perform the clinical examination which may involve simple tests like asking the patient to raise the eyebrows, close the eyes, whistle, smile and wink.
MRI and CT scans may be done to find the location of the compression of the nerve. Electromyography may be done to assess the severity of the paralysis.
Management of Facial Palsy
The main line of treatment for Bell’s palsy involves the use of Corticosteroids like prednisolone which is given with recommended doses. The patient responds better to corticosteroids if brought early to the doctor.
Antiviral drugs like acyclovir may be given in case of associated viral infections. This, however, may not be very effective in curing facial palsy. Vitamin B1, B6, B12 supplements may be given.
Symptomatic treatment to prevent any damage to the eye like lubricating eye drops and eye patches to keep the eyes shut during sleep may be given. Physiotherapy for the facial muscles to prevent further wasting of muscles may be tried on the patient.
Surgical treatment like nerve decompression may be done when there is complete paralysis. This is preferably done within 2-3 weeks of the onset of the condition.
Most of the cases(85%) of bell’s palsy do recover within 3-12 weeks. Few cases do take longer time to recover, which may be around 6 months or more. Some rare cases have an incomplete recovery with either loss of taste, facial spasms, lacrimation (crocodile tear syndrome), facial pain, etc. The chances of recurrence of facial palsy are not rare.