How do normal EMG findings compare with the findings seen in a myopathic disorder?
The weaker a patient with myopathy is, the more likely the needle EMG findings will be abnormal. In patients with very mild weakness or those with steroid myopathy, the needle EMG recording may appear normal.
Electromyography Findings for Normal Muscle and Myopathic Disorders
|Electromyography Findings||Normal Muscle||Myopathy|
|Spontaneous activity||None||Variable fibrillations, positive sharp waves|
|Motor unit action potential morphology||Normal||Small amplitude, short duration, increased polyphasia|