He couldn’t close an eye, smile or move one-half of his face: Was it a stroke or something else?

What exactly is Bell’s palsy?

Bell’s palsy is the sudden weakness or paralysis of the muscles on one side of the face caused by inflammation of the facial nerve, which controls facial expressions. The condition usually develops rapidly, often reaching its peak within 48 to 72 hours.

Because the face suddenly droops, many people immediately think they are having a stroke—and understandably so. But while Bell’s palsy can be alarming, it is usually temporary, and most patients recover completely, especially if treatment begins within the first three days.

Symptoms typically include drooping of one side of the face, difficulty smiling, inability to fully close one eye, drooling, altered taste, increased sensitivity to sound in one ear, and either excessive watering or dryness of the affected eye. Some people also experience pain around the ear before the weakness appears.

Why does it happen?

The exact cause isn’t always known, but doctors believe Bell’s palsy most commonly results from inflammation of the facial nerve, often triggered by the reactivation of dormant viruses such as the herpes simplex virus. The swelling of the nerve as it passes through a narrow bony canal temporarily disrupts its function.

Certain factors appear to increase the risk. People recovering from viral infections, those with weakened immunity, diabetes, pregnancy—particularly during the third trimester or shortly after delivery—and individuals under significant physical or emotional stress may be more susceptible. Lack of sleep may also contribute.

Many people believe that sleeping under a fan or air conditioner causes Bell’s palsy. This is a myth. While prolonged exposure to very cold air may occasionally act as a trigger in susceptible individuals, it is not the direct cause. The condition usually develops because of a combination of underlying biological factors rather than cold air alone.

Bell’s palsy or stroke?

This is the question doctors hear most often. Both Bell’s palsy and stroke can cause the face to droop on one side. But there are important differences. In Bell’s palsy, the facial nerve itself is affected, so the entire half of the face becomes weak. The person usually cannot wrinkle the forehead, raise the eyebrow or completely close the eye on the affected side.

In most strokes, the damage occurs in the brain rather than the facial nerve. As a result, the forehead is often spared because it receives nerve signals from both sides of the brain. A person may have a drooping mouth but can still raise both eyebrows and wrinkle the forehead.

A stroke is also more likely to be accompanied by weakness or numbness of an arm or leg, difficulty speaking or understanding speech, sudden vision loss, severe dizziness, confusion or problems with balance and walking.

However, these differences are not reliable enough for someone at home to make the diagnosis. Every person with sudden facial weakness should be treated as a potential stroke and taken to the nearest emergency department immediately. Time is critical if a stroke is the cause.

Can Bell’s palsy be prevented?

There is no guaranteed way to prevent Bell’s palsy. Maintaining good general health — controlling diabetes and other chronic illnesses, getting enough sleep, reducing stress and seeking timely treatment for infections — may lower the risk, but there is no proven preventive strategy.

Treatment and recovery

The good news is that Bell’s palsy responds well to treatment. Doctors usually prescribe corticosteroids, ideally within 72 hours of symptom onset, because they reduce inflammation of the facial nerve and significantly improve the chances of complete recovery. In selected patients, particularly when a viral cause is strongly suspected, antiviral medicines may also be added.

Protecting the eye is equally important. Since the eyelid may not close properly, the surface of the eye can dry out, increasing the risk of corneal injury. Artificial tears during the day, lubricating ointment at night and sometimes taping the eyelid closed during sleep help prevent complications.

Facial exercises and physiotherapy may also aid recovery in some patients, particularly when weakness is prolonged. Most people begin to recover within a few weeks and regain normal facial function within three to six months, although recovery can take longer in some cases. A small proportion may be left with mild residual weakness or involuntary facial movements.

(The author is senior consultant, Neurology, Indraprastha Apollo Hospital, Delhi)