“COVID arm” detected by MR neurography

Dear Editor,

Here we present the first report of magnetic resonance neurography (MR neurography) clearly detecting “COVID arm” with lymphadenopathy by Moderna COVID-19 vaccine.

A 68-year-old Japanese female suffering from chronic inflammatory demyelinating polyneuropathy had received the first dose of Moderna COVID-19 vaccine in her left shoulder. On the next day of vaccination, she noticed left shoulder pain and swelling (so called “COVID arm”), but she has been free of other post-COVID-19 vaccination symptoms including Parsonage-Turner Syndrome. On that day, she underwent a MR neurography for regular follow-up evaluation of her polyneuropathy. Surprisingly, MR neurography revealed marked swelling of the left deltoid muscle and the left axillary lymph nodes at the injected side (Fig. 1). Although recent reports demonstrated axillary lymph nodal activation on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography after COVID-19 vaccination [[1], [2], [3]], this is the first report of MR neurography detecting “COVID arm”.

Fig. 1.

MR neurography of the cervical nerve roots the next day of Moderna COVID-19 vaccination in the left shoulder detected severe swelling of the left deltoid muscle (arrow heads) and the left axillary lymph nodes (arrows).

Ethics statement

Written informed consent was obtained from the patient for the publication of this case report in accordance with the Declaration of Helsinki.

Study funding

The authors report no targeted funding.

Declaration of Competing Interest

The authors report no disclosures relevant to the manuscript.