Outpatient Physiotherapy for Immune-Mediated Necrotizing Myositis With a Positive Outcome: Must Pathology Equal Dysfunction? A Case Report

BACKGROUND: Necrotizing myositis (NM) is a rare autoimmune systemic condition leading to skeletal muscle destruction visualized on magnetic resonance imaging (MRI). The prognosis is severe progressive muscle weakness leading to functional mobility decline. This case study described outpatient physiotherapy management of NM, not hitherto reported, and the unanticipated outcomes given the diagnosis and MRI findings. CASE PRESENTATION: A 77-year-old female was diagnosed with NM, confirmed on MRI significant for abnormal T2 signal in all muscular compartments of both lower extremities, after 4 months of progressive limb weakness had prevented her from walking independently. Outpatient physiotherapy began 10 months after diagnosis. Examination revealed spinal and peripheral joint hypomobility, lower limb weakness (1 repetition, 30s sit to stand-30STS), functional limitation (14/80, Lower Extremity Functional Scale [LEFS]), and slow gait with rollator. The physiotherapy diagnosis was that musculoskeletal impairments contributed to movement dysfunction, leading to 18 manual therapy and exercise treatments over 19 weeks. OUTCOMES AND FOLLOW-UP: Strength (8 repetition 30STS) and function (49/80 LEFS) improved beyond minimal clinical important differences and gait speed at discharge approximated age-sex-matched normal. DISCUSSION: For this NM case, strength and function improved despite confirmed muscle necrosis and prognosis of progressive muscle degradation after addressing modifiable musculoskeletal impairments. JOSPT Cases 2024;4(4):205-211. Epub 7 October 2024. doi:10.2519/josptcases.2024.0064