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Bell's palsy- etiology, clinical features, investigations and treatment |

BELL'S PALSY (IDIOPATHIC FACIAL NERVE PALSY)

Etiology
Reactivation of latent herpes simplex virus-1 (HSV-1)


Clinical features
Unilateral weakness of facial muscles.Unable to close eye or smile properly on affected side,may be associated with ipsilateral hearing loss.
Diagnosis can be made clinically in patients with:
•Typical presentation
•No risk factors or pre-existing symptoms for other causes of facial paralysis
•No lesions of herpes zoster in external ear canal
•Normal neurological examination with exception of facial nerve involvement.



Investigations (choices include)
In uncertain cases, investigations may include ESR, FBS for diabetes mellitus, Lyme titer, angiotensin-converting enzyme level, abdomen and chest imaging for possible sarcoidosis , lumber puncture for possible Gullain - Barre syndrome or MRI scanning.



Treatment (choices include)
Combination treatment with acyclovir (CYCLOVIR) 800 mg five  times a day and Prednisolone (WYSOLONE ) 60-80 mg /day for 5 days , and tapered over the next week may speed up recovery ( rather than using Prednisolone alone ). Physiotherapy including electrical nerve stimulation may be tried in selected cases.



Key points 
• self - limiting in most cases , although full recovery of affected facial muscle may take up to 3 months .
•patient should protect eye with a patch and artificial tears [MOISOL(methylcellulose ) eyedrops].
• Refer urgently for ophthalmological assessment, if eyelid does not fully cover cornea when closure is attempted.
• Incomplete paralysis in 1st week is favorable sign . recovery is possible.
•Search for underlying cause, if recovery has not started within 6 weeks of onset of symptoms.
• Aberrant reinnervation may occur during course of recovery, giving rise to unwanted facial movements ( e.g. eye closure when mouth is moved) or crocodile tears (tears in eyes during salivation).

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