Bilateral Facial Nerve Palsy and COVID-19 Vaccination: Causation or Coincidence?

Bell's palsy is a mononeuropathy of the facial nerve that typically causes unilateral facial paralysis. The incidence of unilateral Bell's palsy is not uncommon, but sequential or simultaneous bilateral Bell's palsy is exceedingly rare. While unilateral Bell's palsy is oftentimes idiopathic, bilateral Bell's palsy is almost exclusively explained by an identifiable trigger. In pre-clinical trials, Bell's palsy cases were recorded at higher rates in the vaccine cohort than the placebo cohort. Herein, we present a case of isolated sequential bilateral Bell's palsy that after an extensive workup, proved to be idiopathic. Notably, in the setting of a recent coronavirus disease 2019 (COVID-19) vaccine and absence of identifiable etiology, our case highlights a potential correlation of the COVID-19 vaccine and bilateral Bell's palsy.

Automated summary

Bell's palsy is a unilateral facial paralysis caused by a mononeuropathy of the facial nerve, with bilateral cases being rare. While most cases of unilateral Bell's palsy are idiopathic, bilateral cases typically have identifiable triggers. A recent case report highlighted a potential correlation between the COVID-19 vaccine and bilateral Bell's palsy in a patient with no identifiable etiology after thorough investigation.