Bell palsy, or acute idiopathic facial nerve palsy, accounts for 60 to 75% of all
acute facial palsies. It is characterized by a rapid onset (24 to 48 hours), and
may or may not progress to total paralysis. A facial weakness that progresses
slowly over weeks to months is suspicious for a neoplasm.
If there is little to no recovery after 2 to 3 months,
then imaging is recommended to rule out a neoplasm.