Incorrectly, any facial nerve palsy is often referred to as Bell's palsy.

The current thought is that it is caused by a viral infection resulting in swelling of the facial nerve in the temporal bone and compression of the nerve resulting in paralysis. Most ENT's will treat with a course of an antiviral (Valtrex) and steroids.

You uncle needs to go have it evaluated ASAP, since early treatment **MAY** influence prognosis. The sudden onset is a good sign. Slower onset could be a parotid gland tumor or a brainstem tumor. He needs to go to and ENT ASAP as well as an eye doc. The #1 long term problem is eye related since the eye can be unprotected for months while the paralysis resolves.