Bell’s Palsy

January 20,2010

History

- Sir Charles Bell, Scottish Surgeon

- First described in early 1800s based on trauma to facial nerves

- Definition of Bell’s Palsy: Acute peripheral CN VII (facial nerve) palsy of unknown cause

Anatomy

1) Motor to facial muscles2) Parasympathetic innervation to lacrimal, submandibular, sublingual salivary glands3) Afferent fibers for taste on anterior 2/3 tongue4) Somatic afferents to external auditory canal & pinna

Epidemiology

• ½ of all facial palsy’s qualify as “Bell’s Palsy”

• Annual Incidence 10-40/100,000

• Lifetime incidence 1:60

• Risk is 3xs greater in pregnancy, especially 3rd trimester

• Increased risk with diabetes

Cause

• Widely accepted cause is HSV-1, however not proven

• HSV mediates inflammatory/immune response which leads to myelin sheath degeneration, & edema which causes compression and further damage of CN VII

Clinical Features• Sudden onset symptoms,

usually hours w/ maximal weakness w/in 48 hrs

• Unilateral• Eyebrow sagging• Inability to close eye• Loss of nasolabial fold• Decreased tearing• Hyperacusis• Loss of taste to anterior 2/3

tongue• Mouth droop

Differential Diagnosis• Infection

– External otitis Otitis media – Mastoiditis – Chickenpox – Herpes zoster (Ramsey Hunt syndrome) – Encephalitis Poliomyelitis (type I) – Mumps – Mononucleosis – Leprosy – Influenza – Coxsackievirus – Malaria – Syphilis – Tuberculosis – Botulism – Lyme disease

• Tumor, central or local

• Metabolic– DM– Hyperthyroidism– Vitamin A deficiency

• Toxic • Iatrogenic• Idiopathic

– Bell's – Melkersson-Rosenthal syndrome

(recurrent alternating facial palsy, furrowed tongue)

– Amyloidosis – Landry-Guillain-Barre syndrome– Multiple sclerosis – Myasthenia gravis – Sarcoidosis

• Birth • Trauma

Ramsey Hunt Syndrome • AKA Herpes Zoster Oticus: Reactivation of

VZV within geniculate ganglia• Lifetime incidence VZV 10-20%; if live to be

85, 50% • Risk Factors: Age, Malignancy,

Immunosuppressed• Pathophysiology: • 1) Age related immunosenescence• 2) Disease associated immunocompromise• 3) Iatrogenic immunosuppression• Clinical Features

• Acute Vertigo• Hearing loss• Ipsilateral facial paralysis• Ear Pain• Vesicular rash

• Rx: Steroids, acyclovir

Evaluation & Diagnosis

• Bell’s Palsy is a clinical diagnosis based on– typical presentation– absence of other explanation

or other underlying disease– absence of cutaneous lesions– otherwise normal neuro exam

• Possible Labs to check: ESR, RPR, Lyme titer, glucose, PCR if vesicular lesions

• Proceed with imaging (MRI) if– Atypical Presentation– Slowly progressive over 2-

3 weeks– If no improvement in

symptoms in 6 wks

• Electrophysiology (CMAP) performed if complete facial paralysis remains after 1 week of treatment

Treatment

• Manual closing of eye such as with tape while sleeping, lubricating eye drops

• Steroids 60-80 mg daily x 5 days then tapered over next 5 days or 1 mg/kg daily x 7 days

• +/-Acyclovir 400 mg 5xs daily x 10 days vs Valacyclovir 1 g BID x 7 days

• Surgical Decompression – no good evidence to support

Prognosis

• 80% recover within weeks to months

• If motor nerve conduction studies show evidence of denervation after 10 days indicates prolonged recovery of ~ 3 months & possible incomplete recovery