Abstract Details

Does fibres’ inter-distance affect jitter? Tentative results from a multi-channel EMG needle.

State of the art clinical EMG generally use a single electrode needle, which is limited in coverage to a small volume of the muscle necessitating moving the needle within the muscle in order to enhance the signal-to-noise ratio of the recorded muscle fibre(s), which is uncomfortable for patients, and limits results to operator skill.

We have developed a novel multi-electrode system that samples EMG signal from 64 electrodes along the surface of the needle. The electrodes are placed strategically on the needle to allow for localisation of muscle fibres based upon the unique profile of the muscle fibre as it appears on the electrodes along the length of the needle.

In this study we recorded EMG activity in tibialis anterior at varying levels of flexion (10-40% of maximum voluntary contraction), measured with a force transducer. Using advance signal processing method we are able to decompose the EMG signal into the constituent motor units. A novel machine learning approach based on independent component analysis approach and a support vector machine we are able to further tease apart the muscle fibres within the MUs and then localize the position of these fibres relative to the needle. Once muscle fibres are localized we can go back to the single activations of MUs and measure the jitter (in terms of mean consecutive difference, MCD) of the individual fibres.

Data was collected from two healthy volunteers resulting in a total of 96 identified MUs with 2-25 detected fibres in each MU. The mean jitter over all the recorded muscle fibres is 23.19 +/-8.2 µs.
We found for the first time a correlation (0.76 with p-value <0.05) between the fibres’ inter-distance and the relative jitter. These results raise the intriguing possibility that some of the jitter observed originates in the terminal axonal arborisation as opposed to the end plate itself.

TitleForenamesSurnameInstitutionLead AuthorPresenter
Dr.StuartMaitlandNewcastle Univeristy
DrBasharAwwad Shiekh HasanNewcastle University
DrRogerWhittakerNewcastle University
DrEnriqueEscobedo-CousinNewcastle University
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