Morgane Chamboux,Corinne Simon,Frédérique Beau-Salinas,Anaïs Maurier,Marie Sara Agier,Eve Marie Thillard,Bérenger Largeau,Annie-Pierre Jonville-Bera
Response to Letter “Only blames SARS-CoV-2 vaccination for facial palsy after alternative etiologies have been ruled out”
Response to Letter “Only blames SARS-CoV-2 vaccination for facial palsy after alternative etiologies have been ruled out”

ADRadverse drug reactionCOVID-19coronavirus disease 2019CSFcerebrospinal fluidGBSGuillain-Barré syndromePFPperipheral facial palsyRPCregional pharmacovigilance center Dear Editor, We thank the authors for giving us the opportunity to clarify some elements of our article [1]. First of all, as stated in the title and in the method, this is a case series of adverse drug reaction (ADR) reported to our regional pharmacovigilance center (RPC). Then, we were not directly involved in the medical management of these patients. When family physicians, specialist doctors, or patients themselves suspect an ADR such as peripheral facial palsy (PFP), they send us a report (for patient, additional medical records confirming the diagnosis are required). This study was therefore not designed to provide a precise clinical and paraclinical description but to describe the onset patterns (e.g., time to onset) and the risk of recurrence upon reinjection. We have described here the data reported by the practitioners and listed the main complementary examinations detailed in the report, but not the neurological clinical examination, which is a mandatory prerequisite for the diagnosis of PFP. As the authors of this commentary point out, PFP can be part of the manifestations of Guillain-Barré syndrome (GBS), and one of the limitations of the study may be that none of the patients had undergone cerebrospinal fluid (CSF) analysis. For the cases included in our study, the hypothesis of an underlying GBS onset can be reasonably ruled out because all patients were secondarily questioned to obtain the timing of PFP regression and the potential recurrence after subsequent vaccine injections. None of them reported GBS or other suggestive manifestations (e.g., no additional contemporaneous bilateral motor deficits), or hospitalization for any neurological complication during the reported PFP episode. Regarding the need for a routine nerve-conduction study, some of the patients probably had this additional test, but this was not recorded in the physician reports. Indeed, most of the reporters were not the specialists who participated in the conduct of the complementary examinations, and therefore did not have all the results of these possible examinations to communicate to our RPC. According to the latest French recommendations, electroneuromyography is recommended only in cases of severe PFP (Grade V or VI of the House and Brackmann classification) and not systematically [2]. Indeed, diabetes is the most common metabolic cause of facial palsy, which is why this condition was included in the data analysis. Although an elevated HbA1C at the time of PFP makes an exclusive role for vaccination less likely, it does not formally exclude it. We agree with the author of this comment that the term Bell's palsy is to be reserved for the idiopathic form of PFP, therefore in our article we have never used this term to describe our cases of coronavirus disease 2019 (COVID-19) vaccine-associated PFP but only to discuss around the idiopathic form of the “wild type” of the PFP with unknown aetiology. About speech disorders, it was indeed dysarthria. Moreover, all cases were reviewed, precisely to eliminate misreporting diagnosis. This led us to exclude 15 out of 38 cases, as the diagnosis of PFP could not be retained. Among these excluded cases there were one central facial palsy, five hemifacial paresthesia contemporary with a transient edema of the face, one fleeting facial paresis (less than one minute) and one transient speech disorder. Therefore, despite the questions raised, the clinical picture and the chronology of events in the cases described here allow us to retain the diagnosis of peripheral facial palsy post SARS-CoV-2 vaccine.

The authors declare that they have no competing interest.