Facial nerve palsy is a neurological condition in which function of the facial nerve cranial nerve VII is partially or completely lost. It is often idiopathic but in some cases, specific causes such as trauma, infections, or metabolic disorders can be identified. Two major types are distinguished: central facial palsy lesion occurs between cortex and nuclei in the brainstem and peripheral facial palsy lesion occurs between nuclei in the brainstem and peripheral organs. Central facial palsy manifests with impairment of the lower contralateral mimic musculature. In contrast, peripheral facial palsy leads to impairment of the ipsilateral mimic muscles and also affects the eyelids and forehead. Additionally, peripheral facial palsy can cause various sensory and autonomic disorders depending on the exact location of the lesion.
The most common cause of acute onset unilateral peripheral facial weakness is Bell's palsy. The incidence is lowest under 10 years of age and highest in people over the age of Left and right sides are affected equally. Bell's palsy is an acute peripheral facial weakness of unknown cause and the diagnosis can be established without difficulty in patients with unexplained unilateral isolated facial weakness. The onset is sudden and symptoms typically peak within a few days. Additional symptoms may include pain in or behind the ear, numbness or tingling in the affected side of the face usually without any objective deficit on neurological examination, hyperacusis and disturbed taste on the ipsilateral anterior part of the tongue. The mean interval to first recurrence is reported at 9.
Bell's palsy is a type of facial paralysis that results in an inability to control the facial muscles on the affected side. The cause of Bell's palsy is unknown. The condition normally gets better by itself with most achieving normal or near-normal function. Bell's palsy is characterized by a one-sided facial droop that comes on within 72 hours. The facial nerve controls a number of functions, such as blinking and closing the eyes , smiling , frowning , lacrimation , salivation , flaring nostrils and raising eyebrows.