Ramsay Hunt syndrome is caused by infection of:

Varicella zoster virus may also cause facial nerve paralysis when the virus reactivates from dormancy in the nerve. This condition, known as Ramsay Hunt syndrome, is characterized by severe otalgia followed by the eruption of vesicles of the external ear. Treatment is similar to Bell's palsy, but full recovery is only seen in approximately two thirds of cases. Ref: Schwaz's principle of surgery 9th edition, chapter 18.