By Chris Faubel, MD –
Photo from medicalacupuncture.org
EMG disease is a rare condition in which increased insertional activity (positive sharp waves and sometimes fibrillations) is seen in all muscles, in the absence of any known neuropathic, myopathic, or metabolic disorder.
- Normal nerve conduction study
- Short runs of positive sharp waves
- NO waxing and waning, early recruitment, sustained grip, or contractions with thenar muscle tapping (classic signs of myotonia)
Insertional activity is caused by local muscle damage from the passage of the needle.
Positive sharp waves (PSWs) and fibrillations are the result of single muscle fiber action potentials that have a destabilized membrane (such as after denervation of a muscle).
