Effectiveness of High-dose Intravenous Immunoglobulin for Severe Dysphagia in a Case of COVID-19 Vaccine-associated Myositis

Abstract

　Introduction:　Several cases of myositis have been reported after the COVID-19 vaccination, and the concept of COVID-19 vaccine-associated myositis (CVAM) as a distinct disease entity has been proposed. However, no reports have focused on the dysphagia of this condition, and its details are unknown. Here, we report a case of myositis with dysphagia after the COVID-19 vaccination.

　Case:　An 86-year-old woman who lived alone was independent in ADLs, and had no difficulty swallowing regular food. Forty-eight days before admission, she received her third intramuscular injection of the COVID-19 vaccine, Spikevax Intramuscular Injection^® (Moderna Japan). Two weeks later, she developed muscle pain in the limbs and difficulty raising both arms, but these symptoms improved with follow-up observation. She then developed a fever and muscle weakness in the neck, trunk, and limbs, and was urgently admitted to our hospital. On admission, the patient had redness on both forearms and trunk, which gradually worsened and developed blisters with erosions. Muscle weakness in the proximal muscles, predominantly in the upper limbs, also progressed, making it difficult for the patient to stand or move about. Although the patient was on a swallowing-adjusted diet 4, the swallowing worsened and oral intake became difficult, so the patient was placed on total parenteral nutrition. An inflammatory muscle disease was suspected, and methylprednisolone pulse therapy was administered on the 13th day of hospitalization, but was ineffective. On the 41st day of hospitalization, intravenous immunoglobulin therapy (IVIg) was initiated, and from the 46th day, the hypernasal voice and muscle strength of the trunk and proximal muscles improved quickly. On the other hand, the severe dysphagia, mainly due to pharyngeal residue, persisted. Strengthening exercises for muscles involved in swallowing were continued, and the patient was eventually able to ingest a swallowing-adjusted diet 4 and was discharged home on the 132nd day. Based on the negative results for myositis-specific antibodies and clinical course, the patient was ultimately diagnosed with CVAM.

　Conclusion:　We report a case in which dysphagia was thought to be due to CVAM. IVIg was effective in this case, and the recovery of dysphagia was slower compared to the recovery of the cervical flexor muscles and proximal limb muscles.