On electromyography, all of the following features suggest denervation, EXCEPT:
Inseional activity refers to the burst of action potentials that is usually observed when the EMG needle is inseed into the muscle. Increased inseional activity is observed in denervated muscles. Relaxed muscle normally is electrically silent except in the end plate region, but abnormal spontaneous activity occurs in denervation or inflammatory changes in affected muscle. Giant polyphasic potentials arise from motor units containing more than the usual number of muscle fibers that are spread out over a greatly enlarged territory within the muscle. Fibrillation potentials and positive sharp waves (which reflect muscle fiber irritability) and complex repetitive discharges are most often. Ref: Waxman S.G. (2010). Chapter 23. Electrodiagnostic Tests. In S.G. Waxman (Ed), Clinical Neuroanatomy, 26e.
Less inseional activity is observed in denervated muscles
Giant polyphasic potentials arise from motor units
Presence of positive sharp waves
Spontaneous firing of motor units