Traditionally, neuromuscular disorders have been diagnosed with needle EMG, often in combination with motor-nerve conduction studies. In the latter, surface electrodes are widely used to record the compound muscle action potentials.
Other than this, single bipolar surface recordings are not being used in routine electro-diagnosis, because of inherent limitations. They are being used, however, in other fields, such as kinesiology, ergonomics, rehabilitation and sports medicine, where it is important to record on-off switching of muscles or to estimate muscle force.
Obviously, needle EMG also has disadvantages, the most prominent being the invasiveness and the lack of spatial information.
With the above in mind, a number of research groups around the world have started to evaluate the possibilities of high density surface EMG (HDsEMG), using dense arrays of individual electrodes, to obtain information from the muscle. This information is sometimes overlapping, but often complementary to the information extracted by needle EMG
At this point, HDsEMG is still very much in the research phase. It is thought, however, that it may become clinically useful in the assessment of for example motor fiber conduction velocity (MFCV) measurements (see specifications below).
Obvious advantages of HDsEMG are its non-invasiveness (especially attractive in pediatric applications) and its ability to record over very long time periods.