Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Bell’s palsy is a paralysis of cranial nerve VII (the facial nerve) resulting in inability to control facial muscles on the affected side. Several conditions can cause a facial paralysis, e.g., brain tumor, stroke, and Lyme disease. However, if no specific cause can be identified, the condition is known as Bell’s Palsy. Named after Scottish anatomist Charles Bell, who first described it, Bell’s palsy is the most common acute mononeuropathy (disease involving only one nerve), and is the most common cause of acute facial nerve paralysis.
Bell’s palsy is defined as an idiopathic unilateral facial nerve paralysis, usually self-limiting. The trademark is rapid onset of partial or complete palsy, usually in a single day.
It is thought that an inflammatory condition leads to swelling of the facial nerve. The nerve travels through the skull in a narrow bone canal beneath the ear. Nerve swelling and compression in the narrow bone canal are thought to lead to nerve inhibition, damage or death. No readily identifiable cause for Bell’s palsy has been found, but clinical and experimental evidence suggests herpes simplex type 1 infection may play a role.
Doctors may prescribe anti-inflammatory and anti-viral drugs. Early treatment is necessary for the drug therapy to have effect. The effect of treatment is still controversial. Most people recover spontaneously and achieve near-normal to normal functions. Many show signs of improvement as early as 10 days after the onset, even without treatment.
Often the eye in the affected side cannot be closed. The eye must be protected from drying up, or the cornea may be permanently damaged resulting in impaired vision.
Bell’s palsy (or facial palsy) is characterized by facial drooping on the affected half, due to malfunction of the facial nerve (VII cranial nerve), which controls the muscles of the face. Facial palsy is typified by inability to control movement in the facial muscles. The paralysis is of the infranuclear/lower motor neuron type.
The facial nerves control a number of functions, such as blinking and closing the eyes, smiling, frowning, lacrimation, and salivation. They also innervate the stapedial (stapes) muscles of the middle ear and carry taste sensations from the anterior two thirds of the tongue.
Clinicians should determine whether the forehead muscles are spared. Due to an anatomical peculiarity, forehead muscles receive innervation from both sides of the brain. The forehead can therefore still be wrinkled by a patient whose facial palsy is caused by a problem in one of the hemispheres of the brain (central facial palsy). If the problem resides in the facial nerve itself (peripheral palsy) all nerve signals are lost, including to the forehead.
One disease that may be difficult to exclude in the differential diagnosis is involvement of the facial nerve in infections with the herpes zoster virus. The major differences in this condition are the presence of small blisters, or vesicles, of the external ear and hearing disturbances, but these findings may occasionally be lacking (zoster sine herpete).
[tubepress mode=’tag’, tagValue=’Bell’s palsy’]