title: Does quantitative EMG differ myotonic dystrophy type 2 and type 1?
abstract: Genetic testing is considered the only reliable diagnostic approach in myotonic dystrophy. However it has recently been reported that a considerable number of patients with genetically proven types of the disease have unusual phenotypic presentation. The aim of our study was to evaluate motor unit reorganization reflected by various electrophysiological abnormalities in myotonic dystrophies and to compare findings between type 1 (DM 1) and type 2 myotonic dystrophy (DM2). Quantitative electromyography (EMG) recordings in 63 patients (33 with DM1 and 30 with DM2) from the biceps brachii (BB), rectus femoris (RF), first dorsal interosseus (FDI), and tibialis anterior (TA) muscles were analyzed. Mean amplitude and size index (SI) of motor unit potentials recorded in TA and RF muscles, mean potential duration in TA, and mean SI and the number of outliers with amplitude above the normal range in BB were significantly increased in DM2 as compared to DM1. Myotonic discharges were recorded more frequently in DM1 than in DM2. EMG findings significantly differ between DM1 and DM2. The presence of high amplitude potentials in lower limb muscles in DM2 patients, atypical for myogenic muscle lesions, could be explained by muscle fiber hypertrophy observed in muscle biopsies.
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Elzbieta
authors: E
authors: Szmidt-Salkowska
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland. Electronic address: mgawel@wum.edu.pl.
authors: Malgorzata
authors: M
authors: Gawel
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Anna
authors: A
authors: Lusakowska
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Monika
authors: M
authors: Nojszewska
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Marta
authors: M
authors: Lipowska
authors: Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland.
authors: Anna
authors: A
authors: Sulek
authors: Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland.
authors: Wioletta
authors: W
authors: Krysa
authors: Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland.
authors: Marta
authors: M
authors: Rajkiewicz
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Andrzej
authors: A
authors: Seroka
authors: Department of Neurology, Medical University of Warsaw, Warsaw, Poland.
authors: Anna M
authors: AM
authors: Kaminska
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm / Q000502:physiology; D002648:Child; D004576:Electromyography / Q000379:methods*; D055724:Electrophysiological Phenomena; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D020967:Myotonic Disorders / Q000503:physiopathology*; D009223:Myotonic Dystrophy / Q000503:physiopathology*; D010641:Phenotype; D052097:Quadriceps Muscle / Q000502:physiology; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Electromyography; MUP; Myotonic dystrophy type 1; Myotonic dystrophy type 2