Facial palsy 12 h after a first Moderna jab requires pathophysiological disclosure and verification of causality

Letter to the Editor

We read with interest the article by Cellina et al. about a 33 years old female developing left peripheral facial palsy (House-Brackmann score IIII) 12 h after the first dose of the anti-SARS-CoV-2 Moderna vaccine [1]. The general practitioner prescribed prednisone (50 mg/d) for 10 days resulting in complete recovery of the palsy at follow-up 19 days after the vaccine shot [1]. A causal relation between the vaccination and the palsy was established. The study is appealing but raises comments and concerns.

The case description is contradictory. On the one hand the authors described a patient with “deep left latero-cervical pain” and on the other hand they stated that “all symptoms developed without occurrence of pain”. This discrepancy should be solved.

We do not agree with the term Bell's palsy for the clinical presentation in the index case. The term Bell's palsy is reserved for peripheral facial palsy of unknown etiology. Since a causal relation between the SARS-CoV-2 vaccination and the facial palsy was established in the index case, the term Bell's palsy is not appropriate and should be replaced by “peripheral facial palsy”.

As peripheral facial palsy can be associated with Guillain-Barre syndrome (GBS) [2], it would have been interesting to know the results of cerebro-spinal fluid (CSF) investigations, particularly if there was a dissociation between the cell count and the CSF protein level. A dissociation would suggest that the patient had the GBS subtype neuritis cranialis rather than simply unilateral facial nerve palsy. Absence of limb muscle weakness and preserved tendon reflexes do not exclude GBS.

Missing are nerve conduction studies (NCSs) of the facial nerves to document the affection of the peripheral portion of the nerve and to eventually document the regression after application of steroids. The contralateral facial nerve needs to be investigated as well to exclude or confirm subclinical involvement.

A latency of 12 h between the jab and the onset of facial palsy is extremely short, when compared with the 4274 cases of the WHO data set [3]. In the WHO data set facial palsy developed not earlier than 24 h after the vaccination [3]. We should be informed about the pathophysiological background of such a short latency. Do the authors attribute the focal lesion to inflammation of the nerve, to radiculitis, to vsasculitis, or to an affection of the intra-cerebral portion of the nerve?

According to the case description, the patient had slight dysphagia and dysarthria [1]. We should be told how affection of the IXth and Xth cranial nerves was excluded.

We also should know if an acute SARS-CoV-2 infection was excluded by PCR. SARS-CoV-2 infections, like the vaccination, can be complicated by cranial nerve lesions with or without concomitant affection of peripheral nerves.

Overall, the interesting report carries several limitations which challenge the results and their interpretation. Work-up of the palsy was incomplete and a causal link between the vaccination and the palsy remains unproven.

Ethical approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Availability of data and material

All data reported are available from the corresponding author.

Funding

None received.

CRediT authorship contribution statement

JF: design, literature search, discussion, first draft, critical comments, FS: literature search, discussion, critical comments, final approval.

Declaration of competing interest

None.