Bell's palsy is a condition in which there is weakness or paralysis in the muscles that control facial expressions. It involves the muscles in the forehead, eye, cheek, and mouth. Symptoms of Bell's palsy reflect the paralysis of the affected muscles. Those who develop the condition also complain of inability to close their eyes, dryness of the eye, loss of taste sensation, an inability to smile and drooling and facial distortion on the same side as the affected nerve. People experiencing paralysis of the face should see a doctor and exclude more serious causes such as a stroke.
The 12 cranial nerves which communicate with the head and neck connect with the brain. The 7th cranial nerve is called the facial nerve. It is mainly concerned with muscle control and facial sensations. When the facial nerve is affected by inflammation, the muscles that it controls could suddenly become weak and may even become paralyzed. This is the main symptom of Bell's palsy. The exact cause of this inflammation is not yet known, but many believe it is due to viral infection because many people were affected by an infection in the upper respiratory tract before they developed Bell's palsy. Diabetes is also another risk factor for this condition.
Two facial nerves each control one side of the face. When one of them is affected, the muscles on the same side will become weak. One of the muscles that the facial nerve controls is the orbicularis oculi. This surrounds the circumference of the eye and closes the eyelid. When this muscle becomes weak due to Bell's palsy, it may be difficult to close the eye.
People who develop Bell's palsy may become unable to blink or close their eye, even during sleep. As a result, their tears will evaporate more quickly, and they might develop "dry eye." This may lead to irritation of the eye and, if it is not treated, can cause vision impairment. Protective measures include tear-like eye drops or wearing an eyepatch.
The facial nerve controls the buccinator muscle, located within the cheeks. Its job is to make the cheek area flat and pull the angle of the mouth back. This is important to keep the food in the right position during chewing. It also helps with smiling and whistling and helps newborn babies to suckle. When the facial nerve is affected, this muscle becomes weak which makes the person unable to smile properly.
The facial nerve also controls the orbicularis oris muscle. Similar to the orbicularis oculi muscle which surrounds the eye and closes the eyelid, the orbicularis oris muscle surrounds the lips and closes the mouth. Called the kissing muscle, it is also used when playing any brass instrument. Weakness in this muscle may lead to drooling.
The chorda tympani emerges from the front two-thirds of the tongue. It is the branch of the facial nerve responsible for sending taste sensation to the brain. The chorda tympani also plays an important part in stimulating salivation. When the facial nerve is affected, the person can lose the ability to distinguish sweet, sour, bitter, salty and savory tastes. This condition is called ageusia. A different nerve serves the back part of the tongue, so only the front of the tongue is affected in Bell's palsy.
Facial expressions, including raising the eyebrows, are controlled by the frontalis muscle of the forehead. If the facial nerve is affected, this muscle can become weak or paralyzed. That is why people with Bell's palsy will find it difficult to raise the eyebrow on the same side of the affected nerve.
The symptoms and signs of Bell's palsy can be different from one person to another. Some people may experience mild symptoms such as simple weakness, while other people may experience severe muscle paralysis. Occasionally, people feel pain in their ear or behind their ear. Some may become more sensitive to different sounds in the ear present on the same side of the affected nerve. Ear symptoms are due to a branch that emerges from the facial nerve and passes through the ear. These symptoms are usually rare.
Most of the signs and symptoms of Bell's palsy begin suddenly and peak within two days, but they may linger as a facial distortion. The person affected by Bell's palsy will usually complain of speaking difficulty, eating and drinking difficulties as well as pain around the jaw. Some people may feel numbness or reduced sensation in the side of the face affected by Bell's palsy.
Even though the main signs and symptoms of Bell's palsy are present in the face, some people may experience symptoms and signs in other areas of their body. A headache, neck pain, problems remembering and difficulty maintaining balance or a sense of clumsiness may occur. Some people may even feel weakness in their arm or leg on the same side as the affected nerve. These symptoms can be associated with Bell's palsy but can't be explained by facial nerve dysfunction.
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