Clinical and Electrophysiological Findings in Hereditary Inclusion Body Myopathy Compared With Sporadic Inclusion Body Myositis

Abstract

To compare the clinical and electrophysiological findings in hereditary inclusion body myopathy (hIBM) and sporadic inclusion body myositis (sIBM) patients. We retrospectively identified 8 genetically proven hIBM patients and 1 DNAJB6 myopathy with pathological features of hIBM, and compared their clinical, electromyographic, and serological data with a group of 51 pathologically proven sIBM patients. hIBM patients had a younger mean age of onset (36 vs. 60 years, P = 0.0001). Diagnostic delay was shorter in sIBM (6 vs. 15 years, P = 0.0003). Wrist flexors (P = 0.02), digit flexors (P = 0.01), digit extensors (P = 0.02), and quadriceps (P = 0.008) muscles were more frequently affected in sIBM. Fibrillation potentials were more common in sIBM patients (P = 0.03). Electrical myotonia was found in 4 hIBM patients, not significantly different from sIBM patients (P = 0.45). Creatinine kinase was higher in sIBM patients (799 vs 232, P = 0.03). sIBM and hIBM seem to have similar electromyographic changes. The combination of clinical, serological, and histopathological findings can guide genetic testing to the final diagnosis.