Bell’s Palsy
Abnormal movement or paralysis of the face can result from infection, injury, or tumors. The good news is it can be treated.
For instance, a young man develops pain behind his left ear, soon folllowed by an inability to close his left eye, rinse his mouth without water squirting from the left corner of his mouth, twisting of his face to the right side while speaking or attempting to smile. To the patient this all seems pretty scary and much like an acute stroke.
The facial asymmetry worsens over the next 48 hours. Gradually he has difficulty in eating as food gets stuck between his teeth and left cheek. A tiny whisper in the left ear assumes a booming proportion (hyperacusis). Food tastes insipid over the left side of the tongue.
This is a case vignette narrated by Dr. Arun Sharma. Much as it sounds like the begining of a paralytic stroke or brain tumor, thankfully it is Bell's Palsy - a neurological condition that can be managed satisfactorily if diagnosed promptly and treated adequately. The time taken to recover normal eye-closure function and facial expressions is inversely proportional to delay in diagnosis and inadequacy of treatment.
Our face
The Facial or seventh cranial nerve controls 14 of the 17 paired muscles in our face, including the often-forgotten stapedius muscle (the tensor of the ear drum) that regulates the volume of any sound entering the respective ear. The facial nerve orignates in the brainstem and through a narrow, tiny canal (facial canal), emerges behind the ear and trifurcates out into 3 divisions which branch out further and supply signals from the brain to various muscles of the face.
One branch of the Facial nerve also carries taste perception from tongue to the brain for further interpretaion.
The importance of eye-closure and particularly the periodic blinking to run the tearing dynamics, maintaining a constant tear film and reflexive protection of the eye from wind and dust cannot be overemphasized. The paucity of facial expression and stigmatic disfigurement of the face by a wide open unblinking eye, sagging of the face and distortion of the mouth can be quite demoralizing to any one with or without having to make an appearance in public.
Facial paralysis
Bell's Palsy (named after a Scottish anatomist Charles Bell) is an inflammatory condition of the facial nerve that impairs its conductivity, which further gets aggravated by the space constraints of the narrow tunnel in the mastoid bone. This tunnel provides shelter and egress to the Facial nerve into the face; but the bony hardness of the tunnel can be damaging to the delicate nerve.
Paralysis of face can result from a host of infections particularly herpes, diabetes, multiple sclerosis, injury or tumors along the course of the Facial nerve. A thorough evaluation by an experienced neurologist is needed to determine the cause.
According to Dr.Arun Sharma who sees such cases frequently this is pretty common after a viral infection of the upper respiratory tract. It is not the infection per se that is responsible for Bell's Palsy but an inappropriate awry response of the body's immune sytem to the infection in question. The guns of the immune system are somehow retrained on one's own Facial nerve, making it a kind of unintended internecine war.
Most people either wake up to find they have Bell’s Palsy or have symptoms such as dry eye or pain behind the ear that progress to the classic Bell’s Palsy during that same day. Occasionally, symptoms may take a few days to be recognizable as Bell’s Palsy. The degree of paralysis should peak within several days of onset.
WHAT’S HAPPENING TO ME?
A warning sign may be pain in or behind the ear prior to palsy, but it is not usually recognized in first-time cases. Irrespective of the severity of the inital symptoms, the distortion and asymmetry of the face which appear shortly after are the most alarming features of Bell's Palsy. The immediate questions that spring up in the mind are :
- What is the cause?
- When can I expect recovery?
- What can be done to bring about the best possible recovery in the shortest duration of time?
In order get the answers to these queries the patient needs to consult a neurologist at the first available opportunity.
The good News
- Approximately 50 percent of Bell’s Palsy patients recover in a short time (within 3-6 weeks). Another 35 per cent will have a good recovery in the subsequent 9-12 months.
- Regardless of the trigger, Bell’s Palsy is best described as an entrapment neuropathy. The magnitude and time-frame of recovery is dependent on the severity of the initial injury.
- Of course,prompt diagnosis and appropriate treatment are the main determinants of both the magnitude and time-frame of recovery.
- The nerve regenerates at a rate of approximately 1.2 mm per day and can continue to regenerate for 18 months probably or even longer.
From the doctors desk
WEEKEND magazine (Khaleej Times) spoke to Dr.Arun Sharma, Consultant Neurologist at Emirates Hospital, Dubai, about the implications and treatment of Bell’s Palsy.
- Do you see patients suffering from Bell’s Palsy regularly in your practice? Yes, Bell’s Palsy is the commonest form of facial paralysis and about 23 persons out of 100,000 normal people are affected every year. It may occur in any age group. However it tends to spare infants to a certain extent, and it's perceptibly less lenient to the eldest population.
- Does it occur after a viral infection? If No, then, what kind of viral infection. Bell’s Palsy remains an unsolved mystery of modern medicine and is idiopathic by definition. Idiopathic is medical parlance for “cause unknown” Herpes zoster (chicken pox virus hides in the body for years and re-emerges in the form of zoster rash) and simplex (another type of viral infection) both have been identifiably linked to a very small number of Bell’s Palsy cases. Although Bell’s Palsy is commonly known to follow in the wake of nose and throat infections caused by various types of respiratory and glandular viruses, the scientists have not been able to isolate particles of these viruses from the affected nerve tissue and science only moves forward on the shoulders of hard core evidence.
- Does physiotherapy help? Physiotherapy essentially involves exercising the affected muscles of face and eye. Enthusiasm, initiative and vigour invested in the exercise protocol pay proportionately rich dividends.
- Is any particular community more prone to Bell’s Palsy? Bell’s Palsy is eminently non-partisan.
- What are the other causes of facial paralysis that you see in your practice? Facial paralysis may also be caused by blood flow abnormalities in certain area of the brain, tumors in the vicinity of facial nerve, multiple sclerosis, as a part of an acutely crippling disease Guillain Hare Syndrome, sarcoidosis and infection of the parotid gland – a major salivary gland. However, a careful neurological examination can usually rules these disorders out .
