Bell Palsy is the most common cause of unilateral facial weakness.
It is caused by edema and ischemia causing compression of the facial nerve (cranial nerve seven).
While Bell Palsy is by definition an idiopathic facial palsy, the etiology is often infact discovered and attributed to conditions such as Lyme Disease, Herpes Simplex Virus, and HIV.
Classic symptoms of Bell Palsy include:
-- acute onset of unilateral upper and lower facial paralysis (over 48 hr. period)
-- posterior auricular pain
-- decreased tearing
-- hyperacusis (due to stapedius muscle weakness)
-- taste disturbances
Bell Palsy is a diagnosis of exclusion. If the facial paralysis is isolated to the lower face, if there is associated contralateral weakness, and/or if there is diplopia, a central cause for the symptoms, rather than Bell Palsy, must be strongly considered.
