RESUMO
Background Myositis is a group of inflammatory skeletal muscle diseases that in some cases may be linked to vaccines.3 Case reports of new-onset myositis and other autoimmune events have previously been reported after administration of the COVID-19 vaccine. 4–13 Furthermore, three large surveys have described patients with a self-reported flare of myositis following COVID-19 vaccination 14–16 To our knowledge, no cases of flares of myositis causing isolated neck extensor myopathy (INEM) have previously been reported. Case presentation A female known with stable myositis causing isolated neck extensor myopathy (INEM) with minor sequela developed severe weakness of the extensor muscle of the neck three weeks following the Pfizer-BioNTech COVID-19 Vaccine. Until vaccine administration, the patient exhibited a good response to immunosuppressants (prednisolone followed by rituximab). On clinical examination, she had a forward drop of the head and neck extensor muscle strength was 3/5 on the MRC scale. She was initially treated with prednisone and a course of rituximab with no clinical improvement. Subsequently, she was treated with intravenous immunoglobulins (IVIG). Within two weeks neck extensor weakness improved. She no longer had a head drop and neck extensor muscle strength was 4/5 on the MRC scale. The patient had a flare of myositis following immunization. The clinical course suggests that the vaccine may have triggered the flare, which could not be stabilized with previously effective treatment. Conclusions The time period between the COVID-19 vaccine and the exacerbation of myositis causing INEM suggests a link between the vaccine and the flare. The possible need for repeated vaccine boosters to maintain immunity against severe COVID-19 disease highlights the importance of acquiring more information on COVID-19 vaccine reactions in patients with pre-existing autoimmunity and on effective treatments vaccine related flares. Thus, clinicians should be aware of and report possible flares of autoimmune diseases following the vaccine. Nonetheless, the benefits of the COVID-19 vaccine outweigh the small risk of a myositis flare.