A form of temporary facial paralysis, or Bell’s palsy, is caused by trauma or damage to a facial nerve, the 7th cranial nerve, which travels through a narrow bony canal in the skull, beneath the ear. Bell’s palsy is named after Charles Bell, a 19th century Scottish surgeon who was the first to describe this condition. This condition is not uncommon in Kuwait, mostly seen in extremes of climate.
Each facial nerve supplies muscles on one side of face that control blinking and closing, facial expressions such as smiling and frowning, muscles of small bones in middle ear and also impulses to lacrimal glands, salivary glands and taste sensation from tongue. When Bell’s palsy occurs, the function of facial nerve is disrupted causing facial weakness or paralysis. Generally Bell’s palsy affects only one side; however in rare cases it can affect both sides.
The actual cause of this condition is unknown. Most scientists believe that viral infection causes inflammation and edema of facial nerve, which gets compressed in the narrow bony canal resulting in facial paralysis.
Symptoms of Bell’s palsy may include twitching, weakness or paralysis on one side or rarely both side of the face. Other symptoms may include drooping of eyelid and corner of mouth, drooling, dryness of eye, mouth, impairment of taste and excessive tearing from one eye.
A diagnosis of Bell’s palsy is based on clinical presentation, such as a sudden onset of distorted facial appearance and inability to move muscles on the affected side of the face. There are no specific laboratory tests to confirm the diagnosis. But a MRI or CT scan eliminate other structural causes of pressure on the facial nerve.
Mild cases do not require treatment as the symptoms subside within 2 weeks. Steroids are used to reduce inflammation and swelling.
Bell’s palsy can interrupt the natural blinking ability of eyelids resulting in eye irritation and drying. So an important part of treatment is eye protection by artificial eye drops. Physiotherapy is beneficial to stimulate facial nerve to maintain tone of the facial muscles.
The prognosis of Bell’s palsy is very good. In most of the cases recovery occurs in two weeks to six months duration. In rare cases this can recur either on the same side or the opposite side of the face.
Dr. P.C. Koruthu is ENT Surgeon at Shifa Al Jazeera Medical Centre, Farwaniya