Diagnostic des maladies musculaires

Abstract

The clinical evaluation is an essential step to define an accurate phenotype of a myopathy. If a myogenic clinical presentation is usually easy to recognize, we must precise the topographical characteristics of the myopathic process to include it in different subgroups : facioscapulohumeral myopathy and scapuloperoneal syndrome, limb-girdle myopathy, distal myopathy, ocular myopathy… The asymetry or the selectivity of the clinical presentation is also fundamental. This topographical description is best delineated and confirmed by radiological investigations such as muscle CT scan or MRI. Additional clinical signs (early contractures, myotonia…) must be looked for as they are potentially useful to reach a final diagnosis. Serum creatine kinase levels are mandatory but sometimes unconclusive. Normal CK values do not rule out the diagnosis of myopathy. Electrophysiological studies can suggest a myopathic process but it is also very important to detect an associated neuropathy or myotonic discharges. Muscle biopsy usually remains very useful in the precise identification and the definitive diagnosis of a myopathy, even if genetic confirmation is primarily proposed in some cases.