Added value of electromyography in the diagnosis of myopathy: A consensus exercise.
OBJECTIVE
Currently, neurologists may primarily rely on blood biomarkers, muscle biopsy, MRI, and genetics in the diagnostic work-up of suspected myopathy. Using expert consensus as diagnostic reference standard, this study addressed the added value of electrodiagnostic medicine (EDX) in diagnosis of myopathies.


METHODS
One hundred ninety-four EDX evaluations of patients with a peer-review consensus diagnosis of myopathy were collected by seven European centres. Each patient was given three different consensus diagnoses: (1) the EDX diagnosis solely based on EDX results, (2) the pure clinical diagnosis based on all available information except EDX results, and (3) the final diagnosis including EDX and all additional information. The myopathies were grouped as muscular dystrophy (45), inflammatory myopathy (46), other aetiology (36) or unknown aetiology (67).


RESULTS
Higher diagnostic probabilities for myopathy were seen in the final diagnosis compared to the pure clinical diagnosis (p<0.001). Adding EDX information increased the diagnostic probability of myopathy in 67 patients (34.4%). The greatest increase was seen for myopathies of unknown aetiology.


CONCLUSIONS
EDX has a major impact in the diagnosis of myopathies of unknown aetiology. In genetically or biopsy proven myopathies, EDX generally supports the diagnosis.


CONCLUSIONS
EDX is still a useful tool in the diagnostic work-up of most patients with suspected myopathy.
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: kirspugd@rm.dk.
K
K
Pugdahl
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
B
B
Johnsen
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
H
H
Tankisi
Department of Neurology, Saint-Etienne University Hospital, Saint-Etienne, France.
J P
JP
Camdessanché
Institute of Physiology-Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Department of Neurosciences, Hospital de Santa Maria-CHLN, Lisbon, Portugal.
M
M
de Carvalho
Department of Clinical Neurophysiology, Newcastle General Hospital, Newcastle upon Tyne, UK.
P R W
PRW
Fawcett
Department of Neurology, Centre Hospitalier Universitaire, Grenoble, France.
A
A
Labarre-Vila
IRCCS Institute of Neurological Sciences of Bologna and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
R
R
Liguori
Department of Neurology, University Clinics Mainz, Mainz, Germany.
W
W
Nix
Department of Clinical Neurophysiology, Newcastle General Hospital, Newcastle upon Tyne, UK.
I
I
Schofield
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
A
A
Fuglsang-Frederiksen
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D032921:Consensus; D003937:Diagnosis, Differential; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis* / Q000503:physiopathology
Consensus diagnosis; Electrodiagnosis; Electromyography; Multicentre study; Myopathy