Rhabdomyolysis is an acute necrosis of muscle fibers, marked by elevated creatine kinase (CK) levels, muscle pain, edema, and weakness. This study examined the role of electrodiagnostic (EDX) testing compared to genetic testing and muscle biopsy in identifying underlying myopathies in patients with unprovoked rhabdomyolysis. A review of EDX data from 2012 to 2022 identified 66 patients, with 32 showing myopathic findings on electromyography (EMG). Muscle biopsies were conducted in 41 patients, and genetic testing in 37, leading to definitive diagnoses in 15 cases, including metabolic myopathies, muscular dystrophies, and RYR1-related myopathies.

The study found that patients with myopathic EMG often had baseline muscle weakness and elevated CK levels and were more likely to have nonmetabolic myopathies. However, nonmyopathic EMG did not rule out myopathy, as genetic testing identified underlying conditions even when muscle biopsy or EMG results were normal. These findings suggest that genetic testing should be prioritized in diagnosing unprovoked rhabdomyolysis, as it proved crucial in identifying myopathies missed by other diagnostic methods.

Reference: Skolka MP, Milone M, Litchy WJ, Laughlin RS, Rubin DI, Liewluck T. The utility of electrodiagnostic testing in unprovoked rhabdomyolysis in the era of next-generation sequencing. Muscle Nerve. 2024 Aug;70(2):180-186. doi: 10.1002/mus.28087. Epub 2024 Mar 27. PMID: 38533679.