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Wednesday, August 19, 2009

Bell's Palsy

Bell's Palsy
Description
• Acute, idiopathic peripheral palsy of CN VII (facial nerve)
• Complete recovery in 85% of cases without treatment
• Degree of deficit correlates with prognosis:
o Complete lesions have poorest prognosis.
o Partial lesions often have excellent results.
• Recovery usually begins within 2 weeks (often taste returns first) and is complete by 2-3 months:
o Advanced age and slow recovery are poor prognosticators.
• Affects men and women equally
• Age predominance between the third and fifth decade (may occur at any age)
• Incidence 15-40 per 100,000 per year
Etiology
• Innervation to each side of forehead is from both motor cortices:
o Unilateral cortical processes do not completely disrupt motor activity of forehead.
o Only peripheral or brainstem lesion can interrupt motor function of just one side of forehead.
• Idiopathic by definition, but viral cause (particularly herpes simplex) suspected
• Lyme disease, infectious mononucleosis (Epstein-Barr virus [EBV] infection), varicella-zoster infections, and others may cause peripheral seventh nerve palsy.
• Mechanism: edema and nerve degeneration within stylomastoid foramen
Diagnosis
Signs and Symptoms
• Sudden onset of unilateral facial droop, incomplete eyelid closure, and loss of forehead muscle tone:
o Maximal deficit by 5 days in almost all cases (2 days in 50%)
• If forehead muscle tone is not lost, a central lesion is strongly implied (i.e., this is not Bell's palsy)
• Tearing (68%) or dryness of eye (16%) and less frequent blinking on affected side
• The Bell phenomenon (upward rolling of the eye on attempted lid closure) may be seen.
• Subjective “numbnessâ€� of the affected side
• Abnormal taste, drooling
• Hyperacusis (sensitivity to loud sounds)
• Fullness or pain behind mastoid
• Viral prodrome frequently reported
Essential Workup
• Diagnosis is clinical and based on history and physical exam.
• Motor weakness isolated to seventh nerve distribution:
o Involves both upper and lower face
• An otherwise normal neurologic exam including all cranial nerves and extremity motor function
Tests
Lab
• Not helpful in diagnosis of Bell's palsy
• Lyme titers are useful when Lyme disease is suspected or in endemic area
• Tests for mononucleosis (CBC, Monospot) if EBV infection suspected
Imaging
• Not helpful in diagnosis of Bell's palsy
• CNS imaging (CT, MRI) useful if CNS pathology is suspected
Differential Diagnosis
• Brainstem events (mass, bleed, infarct) affecting CN VII almost always involve CN VI (abnormal EOM) and may affect long motor tracts:
o There have been (rare) case reports of isolated CN VII palsy from brainstem disease.
• Lyme disease: history of tick bite, erythema migrans rash, or endemic area
• Zoster (Ramsay-Hunt syndrome): Look for herpetic vesicles, inquire about tinnitus or vertigo.
• Infectious mononucleosis: look for pharyngitis, posterior cervical adenopathy
• Tumors: parotid, bone, or metastatic masses, acoustic neuroma (deafness)
• Trauma: Skull fracture or penetrating facial injury may damage CN VII.
• Middle ear or mastoid surgery or infection, cholesteatoma
• Meningeal infection
• Guillain-Barré syndrome: other neurologic deficits (e.g., ascending motor weakness or diminished deep tendon reflexes [DTRs] present)
• Basilar artery aneurysm; other CN deficits should be present.
• Bilateral peripheral CN VII palsy: Consider multiple sclerosis, sarcoid, leukemia, and Guillain-Barré idiopathic (Bell's) palsy may be bilateral in rare cases.
• Bell's palsy may reoccur; treatment is unchanged.

Treatment
Initial Stabilization
Patients with an isolated peripheral CN VII palsy are stable.
ED Treatment
• Oral steroids may hasten recovery if started within 1 week of onset:
o Complications of therapy are rare and treatment is recommended by many authors.
o Some meta-analyses question efficacy.
• Corneal damage may result from incomplete eyelid closure:
o Lubricating and hydrating ophthalmic preparations is essential/
o Eyelid taping at night
• Acyclovir with steroids may be effective in improving functional nerve recovery:
o Initiate within 72 hours of symptom onset.
• Suspected Lyme disease should be treated with doxycycline or amoxicillin.
• Surgical decompression may be indicated for complete lesions that do not improve; this is controversial.
Medication (Drugs)
• Acyclovir: 400 mg five times per day PO for 7 days (peds: no data to support its use) or valacyclovir 1 g PO for 7 days
• Lacri-Lube: at bedtime and PRN; dryness/irritation in affected eye (or equivalent)
• Prednisone: 30-40 mg PO b.i.d. (or 60 mg PO daily) for 5 days, then taper over 5 days; total 10 days of therapy (peds: 2 mg/kg/d PO [max. 60 mg])
Follow-Up
Disposition
Admission Criteria
Isolated peripheral CN VII palsy does not require admission.

Discharge Criteria
• Isolated peripheral CN VII palsy may be treated on outpatient basis.
• Follow-up should be within 1 week.
References
1. Adour K, et al. Bell's palsy treatment with acyclovir and prednisone compared with prednisone alone. Ann Otol Rhinol Laryngol. 1996;105:371-378.
2. Austin JR, et al. Idiopathic facial nerve paralysis: a randomized double blind controlled study of placebo versus prednisone. Laryngoscope. 1993;103:1326-1333.
3. Gilden D. Bell's palsy. N Engl J Med. 2004; 351:1323-1231.
4. Grogan PM, et al. Practice parameter: steroids, acyclovir, and surgery for Bell's palsy (an evidence-based review). Neurology. 2001; 56(7):830-836.
5. Ramsey JR, et al. Corticosteroid treatment for idiopathic facial nerve paralysis: a meta-analysis. Laryngoscope. 2000;110:335-341.
6. Salinas R, Alvarez G, Ferreira J. Corticosteroids for Bell's palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2004;4:CD001942.
Codes
ICD9-CM
351.0
ICD10
G51.0

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