2-Minute Neuroscience: Bell's Palsy

Bell's

palsy

is a disorder that results from a dysfunction of the seventh cranial nerve, the facial nerve. It involves weakness or paralysis, usually on one side of the face. The onset of the condition is rapid and usually reaches maximum severity within 72 hours. While there may be several causes of facial weakness or paralysis, the cause of Bell's

palsy

is unknown and the diagnosis is made by ruling out other possible causes such as Lyme disease, trauma, tumors, etc. In other words, Bell's palsy is only diagnosed when there is no other identifiable cause of facial palsy. The symptoms of Bell's palsy can vary from case to case in form and severity, but the most common symptom is rapid weakness on one side of the face.

There may be a number of other symptoms arising from facial nerve dysfunction, including drooping eyelid, drooping of one side of the mouth, drooling, inability to close the eye completely, excessive tears and pain in the eye, facial pain, loss of taste. , Hypersensitivity to sound on the affected side, and other symptoms depending on the case. Although the cause of Bell's palsy is unclear, there is evidence that many cases may have a viral origin. Reactivation of latent viruses such as the herpes simplex virus is assumed to be an important factor in many cases of Bell's palsy, but how viruses can damage the facial nerve remains uncertain.

Other factors potentially involved in the development of Bell's palsy include decreased blood flow to the facial nerve and damage to the facial nerve due to inflammation. Most cases of Bell's palsy begin to improve without any medical intervention within a few weeks and fully recover within 3 to 4 months. Less commonly, symptoms may last longer, never go away completely, or go away and then come back.