Caused by lesion on the seventh cranial nerve, bells palsy is characterized by a unilateral facial paralysis. It is further divided into peripheral lesions (patient unable to wrinkle forehead) and central lesions (patient able to wrinkle forehead). Peripheral type can be managed with a steroid burst, acyclovir and an eye patch. Central type will typically require an MRI to look for the lesion.
Bilateral bells palsy can be seen in Lyme disease.