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Bell’s palsy Damage to the seventh cranial nerve
(facial NERVE) that results in partial to complete
PARALYSISof the facial structures on the affected
side. Palsy is an antiquated term for paralysis. The
paralysis is usually temporary, though it may take
up to six months (and occasionally longer) for
nerve function to return to normal. Bell’s palsy is
the most common form of facial paralysis, affect-
ing more than 40,000 Americans each year.
The facial nerve has both motor and sensory
functions. It controls all of the muscles in the face,
the tiny MUSCLEthat moves the stapes BONEin the
middle EAR, the muscles that regulate the flow of
tears from the tear glands (lacrimal glands), and
the muscles that regulate the flow of saliva from
the SALIVARY GLANDS. The facial nerve also conveys
sensory signals for taste from the tongue to the
BRAIN. One facial nerve serves each side of the
face. The facial nerve runs from the base of the
brain through a channel (the fallopian canal) in
the cranial (skull) bones to its emergence at the
base of the earlobe, where it divides into numer-
ous branches that extend across the face.
The damage that results in Bell’s palsy typically
occurs within the fallopian canal. Researchers sus-
pect viral INFECTIONis the primary culprit, as Bell’s
palsy often follows a viral infection such as
INFLUENZA, MENINGITIS, andHERPES SIMPLEX. Trauma
to the head that compresses the facial nerve
within the fallopian canal and extended irritation
such as may occur with prolonged exposure to
intense wind are also circumstances that can cause
Bell’s palsy.

Symptoms and Diagnostic Path
The most prominent feature of Bell’s palsy is facial
distortion resulting from paralysis of the muscles
on the affected side of the face. Rarely, symptoms

may involve both sides of the face. Symptoms

include

• drooping of the eyelid and corner of the MOUTH


• loss of control of the facial muscles


• numbness


• excessive tearing of the EYE


• drooling (SIALORRHEA)


• HEARING LOSSor ear PAIN


• disturbances of taste

The PARALYSIS and other symptoms of

Bell’s palsy strike suddenly, often mim-

icking those of STROKE. For this reason,

immediate medical assessment is cru-

cial. Stroke is life-threatening and

urgent treatment can make the differ-

ence for optimal recovery.

The diagnostic path includes a NEUROLOGIC

EXAMINATION and assessment of personal health

history, particularly for any recent viral infections

or circumstances that cause compression or

inflammation of the facial nerve. The doctor may

conduct imaging procedures such as COMPUTED

TOMOGRAPHY (CT) SCAN, or MAGNETIC RESONANCE

IMAGING(MRI) to rule out stroke, tumor, BRAIN HEM-

ORRHAGE, and other possible causes of the symp-

toms. An electromyogram (EMG) may show the

extent to which the nerve damage affects the

facial muscles. The doctor makes the diagnosis of

Bell’s palsy after ruling out other possible condi-

tions.

Treatment Options and Outlook

Treatment for Bell’s palsy targets the cause of the

nerve damage when the cause persists, which may