Rise (Time) of qEMG


Dr. Michael A. Leitch, Mr. Mark Wyatt & Professor John L. Corbett

Quantitative Electromyography (qEMG) is set to revolutionize the electrophysiology landscape in Australia.

Coastal Neurophysiology is proud to announce its procurement of groundbreaking qEMG technology. CNS recently invested in eight new Cadwell NCS/EMG beta software systems which are shared with the Mayo Clinic and are not yet in general use anywhere else in Australia; although this situation is very likely to change shortly.

Conventionally, Neurologists/Neurophysiologists have performed EMG using visual, qualitative (analogue) methods to distinguish normal from abnormal motor units and analyse patterns indicating specific diseases. Technologies associated with these methods have always had limitations, which qEMG technological advancements can overcome.

Neurologists/Neurophysiologists can now use statistical, objective, quantitative, (digital) means to interpret data; whereas qualitative analysis has always been highly dependent on the clinician’s subjectivity (consequently, different Electrophysiologists would sometimes reach different diagnostic conclusions after studying the same patient).

Additionally, qEMG data can be analysed and re-played offline (at leisure). This allows for more detailed analysis of the sampled motor units (which takes approximately 10-15 minutes per muscle); compared with qualitative methods, which are performed instantaneously.

The main advantage of qEMG is that several parameters (including duration, amplitude, rise-time, turns, phases, discharge rates, thickness and other parameters) can now be derived, so as to enable more reliable conclusions to be drawn about normal and diseased muscles and provide crucial information about the neurological state of the muscle (neurogenic, myopathic or normal). When using qualitative methods, the examiner must infer all of this information in a very short period of time, which is extremely difficult, even for the most experienced clinician. (Imagine reporting on a CT scan in only seconds!)

Furthermore, qEMG allows for the vigilant analysis of multiple individual motor unit potential (MUPs) from the one muscle (at least 20 are recommended), whereas qualitative methods rely heavily on the presence of one or a small number of abnormal potentials.

Another parameter that can now be analysed using qEMG is the Interference Pattern (IP), which is the sum of multiple MUPs firing simultaneously during maximal voluntary contractions. This is vital in determining if a muscle is pathologically myogenic.

These major breakthroughs – as well as future advancements – in technology are predicted by some world authorities to cement qEMG as the gold standard internationally for neurophysiology testing.

CNS is the only large private bulk-billing neurophysiology diagnostic service in QLD and Northern NSW, with clinics in Brisbane, Ipswich and the Gold Coast. We continue to provide bulk-billing for nerve conduction studies (NCS), EMG and, in many cases (where only a few muscles require testing), qEMG with associated Neurologist consultation.

Due to the long-term Medicare freeze, we may be unable to guarantee bulk-billing in cases where multiple muscles require testing (for example, in patients with suspected axial cervical or lumbar spinal pathology), as this requires more complex analysis that can take several hours to complete, and which cannot be completed for the current fee which Medicare has set for this Item Number.

For more information about qEMG or our other services please phone 07 5503 2499 or visit www.coastalneuro.com.au. Please stay tuned, as we intend to provide further information about the qEMG revolution in the coming months.

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