Electromyogram may be helpful in the diagnosis of<unk>  and dermatomyositis. Findings suggestive of<unk>  and dermatomyositis include delay in electrical signals between the muscles and nerves when they are stimulated, polyphasic, short, small motor-unit potentials, and fibrillation, positive sharp waves, increased insertional irritability. The first sign of improvement in<unk>  and dermatomyositis is the disappearance of fibrillation potentials. Electromyogram may also be used to identifying active sites of myositis for biopsy, follow up, and the treatment efficacy. Skin biopsy may be used in dermatomyositis, which demonstrates poikiloderma, epidermal atrophy, and liquefaction degeneration of the basal cells. Histochemical staining might be helpful to differentiate<unk>  and dermatomyositis from lower-motor-neuron diseases.
Polymyositis and dermatomyositis other diagnostic studies
Dermatomyositis other diagnostic studies
Polymyositis and dermatomyositis diagnostic study of choice
Polymyositis and dermatomyositis risk factors
Polymyositis and dermatomyositis differential diagnosis
Multiple sclerosis other diagnostic studies
Scleroderma other imaging findings
Adrenoleukodystrophy other imaging findings