Quantitative Electromyography (QEMG) An electromyography study (EMG) tests the electrical activity of muscles and EMG is useful in the diagnosis of conditions of acute and chronic pain and to identify peripheral nerve or muscle abnormalities, anterior horn cell diseases, root lesions, plexopathies, peripheral neuropathy, entrapment syndrome, neuromuscular junction abnormalities, and myopathies. A monopolar EMG needle electrode is manually inserted into the muscles and the muscle is examined under three phases of muscle activity: when the muscle is resting completely, minimal activity and maximal activity. The results from the EMG can determine the site, duration, extent, and the degree of axonal involvement. Since 1982, as the Director of the Electrodiagnostic Laboratory within the University of Pennsylvania's Department of Rehabilitation Medicine, Jennifer Chu, M.D., performs quantitative electromyography (QEMG) in the evaluation of patients with acute or chronic nerve related muscle pain. In a QEMG, the shape, size, and electrical activity pattern of the functioning muscle signals known as motor unit action potentials (MUAPs) are analyzed. The results help to determine if the patient's symptoms are due to the nerves, muscles and/or nerve-muscle junction (trigger point) problems. Dr. Chu has determined useful parameters with QEMG to diagnose the extent and the degree of nerve irritation and give an approximate timing of abnormality in function of the nerves. Many patients who have had "normal" EMGs may show significant involvement of spinal nerve roots with a QEMG. This type of EMG is essential not only for early diagnosis of the pain symptoms but also essential to predict the outcome to the eToims® testings. While performing QEMG, Dr. Chu searches for signs of recent or ongoing nerve re-growth (re-innervation) because when that is present, it signifies the presence of recent nerve death (denervatlon). Finding re-innervation permits Dr. Chu to identify which nerve roots are irritated. Nerve root irritation may not be accompanied by signs of overt denervation. Therefore, a QEMG allows better diagnostic capabilities than qualitative EMGs where overt abnormalities have to occur before they can be detected. Dr. Chu's findings of re-innervation permit her to identify which nerve roots are irritated even when there is an absence of overt denervation signs, which is the case of partial nerve-root injuries where the signs of overt denervation are not usually present. Thereby, the detection of re-innervation is essential to correctly diagnose the cause of the nerve-related symptoms. With the QEMG, Dr. Chu assesses the sites and extent of nerve-root irritation, the number of involved nerve roots, and the approximate timing of a nerve-root injury.
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nerves for assessment of neuromuscular disorders. It is performed in order to objectively document, interpret, and assess the muscles of a patient for neuromuscular disorders when that patient complains of having such symptoms as pain, fatigue, cramping, numbness, tingling, and/or abnormal sensations and/or muscular weakness.
There are two types of EMGs - qualitative and quantitative, the difference being the extent of the sensitivity to detect abnormalities in nerve and muscle function. Quantitative Electromyography (QEMG) is more sensitive and is used for the early diagnosis of pain, numbness and/or weakness resulting from disease or trauma to the nerves or muscles. 
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