UMEM Educational Pearls

Category: Neurology

Title: Is There a Seasonal Variation to Bell's Palsy?

Keywords: Bell's palsy, facial palsy, Lyme disease, Borrelia burgdorferi (PubMed Search)

Posted: 2/24/2021 by WanTsu Wendy Chang, MD (Updated: 4/24/2024)
Click here to contact WanTsu Wendy Chang, MD

  • Bell’s palsy can be caused by herpes simplex virus-1 (HIV-1) and Lyme borreliosis.
  • Prior studies have found higher incidence of Bell’s palsy in colder months possibly related to reactivation of latent HSV-1.
  • A recent study looked at the incidence and seasonal variation of positive Lyme tests in Bell’s palsy patients in a Lyme-endemic area (New Jersey).
    • Over a 5-year period, 81% of 442 patients with Bell’s palsy were tested for Lyme and 16% tested positive.
    • The months May through October had a 7.2 times higher incidence of positive Lyme tests in Bell’s palsy patients, with the peak in July.
    • May through October also had a 1.3-fold increased ED visits for Bell’s palsy, also peaking in July.

Bottom Line: In a Lyme-endemic area, the incidence of positive Lyme tests and Bell’s palsy are highest in the Lyme months. This seasonal variation may help guide the management of patients with Bell’s palsy.



Pacheco A, Rutler O, Valenzuela I, Feldman D, Eskin B, Allegra JR. Positive tests for Lyme disease and emergency department visits for Bell’s Palsy patients. J Emerg Med. 2020;59(6):820-827.

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