Abnormal EMG Activity Types

Abnormal EMG Activity Types

Fasciculations

Fibrillations

• Involuntary rapid muscle twitches that can be felt
• Fasciculations without other neurologic findings are benign
• Indicate lower motor neuron disease when accompanied by weakness or atrophy
• Irregular, single discharges occurring on background of ongoing EMG activity

• Occur when a muscle fiber loses contact with its innervating axon, producing a spontaneous action potential
• No pathological significance if they have irregular potentials

Myotonic Discharges

Neuromyotonic Discharges

• Motor unit action potential bursts that are irregular in frequency
• May occur in singlet, doublet, triplet, or multiplet discharges
• Intra-burst frequency of discharge may be up to 200 Hz

• Exhibit characteristic waxing and waning in frequency