What causes Bell’s palsy?
Bell’s palsy occurs when the seventh cranial nerve becomes swollen or
compressed, resulting in facial weakness or paralysis. The exact cause of
this damage is unknown, but many medical researchers believe it’s most
likely triggered by a viral infection.
The viruses/bacteria that have been linked to the development of Bell’s
palsy include:
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herpes simplex, which causes cold sores and genital herpes
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HIV, which damages the immune system
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sarcoidosis, which causes organ inflammation
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herpes zoster virus, which causes chickenpox and shingles
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Epstein-Barr virus, which causes mononucleosis
Lyme disease, which is a bacterial infection caused by infected ticks
It is believed to be due to a swelling of the nerve that controls the
muscles of the face.
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It can be worrying, but most people make a full recovery
how it occurs ?
Most doctors believe that it’s due to damage to the facial nerve, which
causes swelling. This nerve passes through a narrow, bony area within the
skull. When the nerve swells -- even a little bit -- it pushes against the
skull's hard surface. This affects how well the nerve works
Researchers have long believed that viral infections may also play a role in the
development of Bell's palsy. They’ve found evidence that suggests the herpes
simplex 1 virus (a common cause of cold sores) may be responsible for a large
number of cases.
Facial nerve

AltWith Bell's palsy, the
nerve that controls your facial
muscles, which passes through
a narrow corridor of bone on its
way to your face, becomes
inflamed and swollen — usually
related to a viral infection.
Besides facial muscles, the
nerve affects tears, saliva, taste
and a small bone in the middle
of your ear.
Other commonly mentioned triggers include:

stress,

trauma,

fever, and

tooth extractions.
.
Who gets it?
Bell's palsy afflicts approximately 40,000 Americans each year. It affects men
and women equally and can occur at any age, but it is less common before age
15 or after age 60. It disproportionately attacks people who have diabetes or
upper respiratory ailments such as the flu or a cold.
Assessment of bell's palsy :_
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In patients presenting with facial weakness, the first priority is to exclude an
upper motor neurone lesion; important associated signs may include concurrent limb
weakness, hyper-reflexia, upgoing plantars, or ataxia
Check for causes of a lower motor neurone lesion by examining the ears,
mastoid region, oral cavity, eyes, scalp, and parotid glands
Bell’s palsy is a diagnosis of exclusion, and oral steroids are needed within 72
hours to increase the chance of complete recovery. Prognosis is usually good
compared with other causes of lower motor neurone weakness, such as tumours and
Ramsay Hunt syndrome
Eye protection is crucial if lid closure is impaired
The facial nerve is responsible for motor supply to the muscles
of facial expression (frontalis, orbicularis oculi, buccinators,
and orbicularis oris) and stapedius, parasympathetic supply to
the lacrimal and submandibular glands, and sensory input from
the anterior two thirds of the tongue. Thus, as well as a facial
droop, patients may present with a dry eye, reduced corneal
reflex, drooling, hyperacusis, altered taste, otalgia, and speech
articulation problems.5
Upper motor neurone
After identifying the affected side, it is important to establish
whether an upper motor neurone lesion is responsible for the
facial weakness. Although not an infallible sign,3classic
neurology describes a bilateral innervation of that part of the
facial nuclei supplying the forehead, and thus preserving
forehead movement in upper motor lesions. Lower motor
neurone disorders of the main nerve trunk result in a weakness
of the entire side of the face.
Patients may have risk factors for stroke, which include older
age (>60 years), hypertension, previous stroke or transient
ischaemic attack, diabetes, high cholesterol, smoking, and atrial
fibrillation.6Corroborative evidence may also be found by
examining for abnormalities in other cranial nerves and the
peripheral nervous system—increased tone, limb weakness,
hyper-reflexia, upgoing plantars, and sensory loss.4
When an upper motor neurone lesion is suspected, it may help
to determine whether this is localised to the brainstem or cerebral
cortex. Brainstem disease may present with vertigo, ataxia, or
crossed neurology signs (ipsilateral cranial nerve involvement
and contralateral hemiplegia). A cortical lesion often affects the
contralateral limbs and involuntary movements of the face, such
as spontaneous smiling, may be spared.6Urgent referral to
secondary care (neurology or acute medical unit) is needed at
this stage to assess the need for thrombolysis.
Lower motor neurone
PHYSICAL EXAMINATION