Myotonic discharges are a frequent symptom in myofibrillar myopathies

Aims: In patients with myofibrillary myopathies (MFM), myotonic discharges have occasionally been detected by needle electromyography (EMG). Nevertheless, this peculiar type of spontaneous serial discharges has not attracted special interest in the genetically heterogeneous MFMs. Patients: Therefore, the EMG and histopathological features were analysed in 6 patients with genetically confirmed MFM (n=1 MYOT, n=1 DES, n=2 ZASP, n=2 FLNC). Results: Fibrillations, positive sharp waves and myotonic discharges were found in all 6 patients, pseudomyotonic discharges in 5. Myotonic discharges were detected in about 50%…