title: Motor unit number estimation as a complementary test to routine electromyography in the diagnosis of amyotrophic lateral sclerosis.
abstract: Electromyographic (EMG) abnormalities that reveal denervation and reinnervation caused by lower motor neuron degeneration do not reflect the number of motor units that determines muscle strength. Consequently, motor unit activity potential (MUAP) parameters do not reflect muscle dysfunction. The aim of the study was to compare the value of motor unit number estimation (MUNE) and MUAP parameters as indicators of clinical muscle dysfunction in patients with amyotrophic lateral sclerosis (ALS), and to analyze the role of MUNE as a supplement to the EMG criteria for the diagnosis of ALS. In 25 patients with ALS, MUNE by the multipoint incremental method in the abductor digiti minimi (ADM) and quantitative EMG in the first dorsal interosseous (FDI) were obtained. The Medical Research Council (MRC) scale was used to evaluate clinical muscle dysfunction. A strong correlation between the number of motor units evaluated by MUNE and ADM clinical function by the MRC scale was found (P<0.001). An increased value of surface-detected single motor action potential was associated with a decreased MRC score for ADM (P<0.1). No relation was found between MUAP parameters in FDI and MRC scores. Our data support the value of the MUNE method for the detection of motor unit loss in ALS, and it could be postulated that MUNE studies may be considered complementary tests for ALS in a future revision of ALS criteria.
authors.affiliation: Department of Neurology, Medical University of Warsaw, Banacha 1A st, 02-097 Warsaw, Poland. Electronic address: mgawel@wum.edu.pl.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Gawel
authors.affiliation: Department of Engineering of Nervous and Muscular System, Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Ks. Trojdena 4 st., 02-109 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Zalewska
authors.affiliation: Department of Neurology, Medical University of Warsaw, Banacha 1A st, 02-097 Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Lipowska
authors.affiliation: Department of Neurology, Medical University of Warsaw, Banacha 1A st, 02-097 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kostera-Pruszczyk
authors.affiliation: Department of Neurology, Medical University of Warsaw, Banacha 1A st, 02-097 Warsaw, Poland.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Szmidt-Salkowska
authors.affiliation: Department of Neurology, Medical University of Warsaw, Banacha 1A st, 02-097 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kaminska
mesh_terms: D000010:Abducens Nerve / Q000503:physiopathology; D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology; D004576:Electromyography / Q000379:methods*; D005260:Female; D005528:Foot / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D011999:Recruitment, Neurophysiological / Q000502:physiology*
keywords: Amyotrophic lateral sclerosis; Electromyography; Motor unit number estimation