Search

A 26-year-old Japanese woman developed a fever, myalgia and gait disturbance one day after receiving the second dose of the mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. A neurological examination revealed symmetrical weakness and myalgia in proximal lower limbs, and a blood examination showed prominent elevation of creatinine kinase. Magnetic resonance imaging (MRI) revealed a high signal intensity in the thigh muscles on short-tau inversion recovery images, and antibody testing revealed positive findings for anti-signal recognition particle (SRP) antibody. Thus, anti-SRP antibody-positive immune-mediated myopathy was diagnosed. We initiated immunotherapy, and she was ultimately able to walk stably.

Amyotrophic lateral sclerosis (ALS) due to a fused in sarcoma (FUS) P525L mutation is characterized by a rapidly progressive course. Multifocal motor neuropathy (MMN) may resemble ALS in early stage and is associated with anti-ganglioside antibodies. A 38-year-old woman was admitted to our hospital because of progressive muscle weakness in the right limbs. She had mild mental retardation and minor deformities. Initially, we suspected MMN given the asymmetric muscle weakness and detection of anti-ganglioside antibodies. However, physical and electrophysiological tests did not support MMN, instead suggesting ALS. We confirmed a heterozygous P525L mutation and finally diagnosed this case as ALS due to an FUS mutation.

Rheumatoid vasculitis (RV) usually occurs in patients with refractory rheumatoid arthritis (RA). An 80-year-old woman was transferred to our hospital because of muscle weakness and paresthesia in all 4 limbs. She had been diagnosed with RA 30 years ago and achieved sustained clinical remission. At presentation, polyarthritis and drop foot were observed, and rheumatoid factor was prominently elevated. A peripheral nerve conduction test revealed mononeuritis multiplex in her limbs. We suspected that RV had developed rapidly despite RA having been stable for many years and started immunosuppression therapy with steroids combined with azathioprine. The treatment prevented worsening of muscle weakness and paresthesia.