Author:
Robert F.McCormack
Richard S.Krause
Description
- Acute, idiopathic peripheral CN VII (facial nerve) palsy
- Complete recovery in 85% of cases without treatment
- Degree of deficit correlates with prognosis:
- Complete lesions have poorest prognosis
- Partial lesions often have excellent results
- Recovery usually begins within 2 wk (often taste returns first) and is complete by 2-3 mo:
- 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)
- Diabetes and pregnancy increase risk
- Incidence: 15-40 per 100,000 per year
Etiology
- Idiopathic by definition, but viral cause (particularly herpes simplex) suspected
- Possible infectious causes which may cause peripheral seventh nerve palsy:
- Lyme disease
- Infectious mononucleosis (Epstein-Barr virus [EBV] infection)
- Varicella zoster infections
- Mechanism: Edema and nerve degeneration within stylomastoid foramen
- Innervation to each side of forehead is from both motor cortices:
- Unilateral cortical processes do not completely disrupt motor activity of forehead
- Only peripheral or brainstem lesion can interrupt motor function of just 1 side of forehead
Signs and Symptoms
History
- Sudden onset:
- Unilateral facial droop
- Incomplete eyelid closure
- Loss of forehead muscle tone
- Maximal deficit by 5 d in almost all cases (2 d in 50%)
- Tearing (68%) or dryness of eye (16%) and less frequent blinking on affected side
- Subjective “numbness” of the affected side
- Abnormal taste, drooling
- Hyperacusis (sensitivity to loud sounds)
- Fullness or pain behind mastoid
- Viral prodrome frequently reported
Physical Exam
- Unilateral facial palsy including the forehead
- If forehead muscle tone is not lost, a central (upper motor neuron lesion) is strongly implied (i.e., this is not Bell palsy)
- Motor weakness isolated to seventh nerve:
- Involves both upper and lower face
- An otherwise normal neurologic exam including all cranial nerves and extremity motor function
- The Bell phenomenon (upward rolling of the eye on attempted lid closure) may be seen
Essential Workup
Diagnosis is clinical and based on history and physical exam
Diagnostic Tests & Interpretation
Lab
- Not helpful in diagnosis of Bell 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 palsy unless a parotid tumor, mastoiditis, etc. are suspected
Differential Diagnosis
- Brainstem events (mass, bleed, infarct) affecting CN VII almost always involve CN VI (abnormal EOM) and may affect long motor tracts:
- 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
- Meningitis: Other signs/symptoms present
- Guillain-Barre syndrome: Other neurologic deficits are present (e.g., ascending motor weakness, diminished deep tendon reflexes)
- Basilar artery aneurysm: Other CN deficits should be present
- Bilateral peripheral CN VII palsy: Consider multiple sclerosis, sarcoidosis, leukemia, and Guillain-Barre. Idiopathic (Bell) palsy may be bilateral in rare cases
- Early HIV infection
- Bell palsy may reoccur; treatment is unchanged
Prehospital
None
Initial Stabilization/Therapy
Patients with an isolated peripheral CN VII palsy are stable
ED Treatment/Procedures
- Corneal damage may result from incomplete eyelid closure:
- Lubricating and hydrating ophthalmic preparations are often needed
- Eye patching at night
- Oral steroids may hasten recovery if started within 1 wk of onset (preferably w/in 72 hr):
- Complications of therapy are rare
- Antiviral therapy (acyclovir or valacyclovir) with steroids may be effective in improving functional nerve recovery:
- Initiate within 72 hr of symptom onset
- No clear proven benefit
- May be indicated for severe palsy
- 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
First Line
- Lacri-Lube or artificial tears: At bedtime and PRN; dryness/irritation in affected eye (or equivalent)
- Prednisone: 60-80 mg PO daily for 7 d (peds: 2 mg/kg/d PO [max 80 mg])
Second Line
Valacyclovir 1 g PO t.i.d for 7 d (peds: 20 mg/kg t.i.d) may be useful in severe cases
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 Recommendations
Follow-up should be within 1 wk