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Bell's Palsy

Bell's Palsy is a topic covered in the 5-Minute Emergency Consult.

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  • 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 1st) and is complete by 2–3 mo:
    • Advanced age and slow recovery are poor prognosticators
  • Affects men and women equally
  • Age predominance between the 3rd and 5th decade (may occur at any age)
  • Diabetes and pregnancy increase risk
  • Incidence 15–40 per 100,000 per year
  • The most common cause of facial nerve palsy in children


  • 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 7th nerve palsy
  • 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

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Rosen, Peter, et al., editors. "Bell's Palsy." 5-Minute Emergency Consult, 5th ed., Lippincott Williams & Wilkins, 2016. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307640/all/Bell's_Palsy.
Bell's Palsy. In: Rosen P, Shayne P, Barkin AZ, et al, eds. 5-Minute Emergency Consult. 5th ed. Lippincott Williams & Wilkins; 2016. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307640/all/Bell's_Palsy. Accessed April 25, 2019.
Bell's Palsy. (2016). In Rosen, P., Shayne, P., Barkin, A. Z., Wolfe, R. E., Hayden, S. R., Barkin, R. M., & Schaider, J. J. (Eds.), 5-Minute Emergency Consult. Available from https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307640/all/Bell's_Palsy
Bell's Palsy [Internet]. In: Rosen P, Shayne P, Barkin AZ, Wolfe RE, Hayden SR, Barkin RM, Schaider JJ, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2016. [cited 2019 April 25]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307640/all/Bell's_Palsy.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Bell's Palsy ID - 307640 ED - Rosen,Peter, ED - Shayne,Philip, ED - Barkin,Adam Z, ED - Wolfe,Richard E, ED - Hayden,Stephen R, ED - Barkin,Roger M, ED - Schaider,Jeffrey J, BT - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307640/all/Bell's_Palsy PB - Lippincott Williams & Wilkins ET - 5 DB - Emergency Central DP - Unbound Medicine ER -