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 muscles 2)Parasympathetic innervation to lacrimal, submandibular, sublingual salivary glands 3)Afferent fibers for taste on anterior 2/3 tongue 4)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 3 rd 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 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