Bell’s Palsy is one of those rare ailments, and one that annoys more than threatens, but can be difficult and socially awkward for sufferers. It’s also one that still baffles researchers as to its cause. And also for an effective treatment.
According to facialpalsy.org,
The name ‘Bell’s palsy’ comes from 19th-century Scottish anatomist and surgeon Sir Charles Bell, who discovered that severing the seventh cranial (or facial) nerve causes facial paralysis.
It has no vaccine, no known method for prevention, and the treatment is still uncertain.
Wikipedia tells us:
Bell’s palsy is a form of facial paralysis resulting from a dysfunction of the cranial nerve VII (the facial nerve) causing an inability to control facial muscles on the affected side… 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 (>80%)… The hallmark of this condition is a rapid onset of partial or complete paralysis that often occurs overnight.
It also says:
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…
Some viruses are thought to establish a persistent (or latent) infection without symptoms… Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell’s palsy. Studies suggest that this new activation could be preceded by trauma, environmental factors, and metabolic or emotional disorders, thus suggesting that a host of different conditions may trigger reactivation.
Which, in essence, doesn’t tell us a lot about the actual cause or why it recurs; mostly it remains guesswork. Bell’s Palsy affects about 20 people per 100,000 population, and the incidence increases with age and with certain medical conditions.