Can M-Mode Ultrasound Imaging of Muscle Tissue Motion Replace Invasive Electromyography for Measuring Muscle Activation?

PurposeThe assessment of deep muscle activation is considered essential for the rehabilitation of spinal and joint pathology. M-mode ultrasound provides a differentiated image of muscle activation. M-mode is, in contrast to the standard fine-wire electromyography (fwEMG) technique, non-invasive. The relationship between M-mode, fwEMG and torque measurements of the onset of hip abductor muscle activation was investigated.Material & Methods14 volunteers were enrolled. Toshiba XarioXG, 7.5 Mhz linear probe, longitudinal M-mode scan (highest swipe speed) and fwEMG of gluteus medius and minimus, dynamometry were used. The onset of isometric hip abduction was measured at intensities of 20%, 40% and 60% of maximal torque. Activation onsets were correlated and patterns of onset time differences were identified.ResultsCorrelation of M-mode and fwEMG onsets was high (r>0.9). Motion and excitation onset differed by 5.1 ms (C.I. ±15.4 ms) and -4.1 ms (C.I. ±12.4 ms) for gluteus medius and minimus, respectively. Coincidentally, significantly different onset patterns were found for gluteus minimus of the four subjects with underlying pathology, p = 0.028 for M-mode and p = 0.042 for fwEMG, related to torque.ConclusionWith pathology, an altered sequence of the mechanical and electrical activation phase was found. M-mode measurements could not substitute fwEMG. However, M-mode measurements were as indicative of the functional differences as fwEMG. M-mode is a promising, non-invasive tool for assessing impaired muscle function. PurposeThe assessment of deep muscle activation is considered essential for the rehabilitation of spinal and joint pathology. M-mode ultrasound provides a differentiated image of muscle activation. M-mode is, in contrast to the standard fine-wire electromyography (fwEMG) technique, non-invasive. The relationship between M-mode, fwEMG and torque measurements of the onset of hip abductor muscle activation was investigated. The assessment of deep muscle activation is considered essential for the rehabilitation of spinal and joint pathology. M-mode ultrasound provides a differentiated image of muscle activation. M-mode is, in contrast to the standard fine-wire electromyography (fwEMG) technique, non-invasive. The relationship between M-mode, fwEMG and torque measurements of the onset of hip abductor muscle activation was investigated. Material & Methods14 volunteers were enrolled. Toshiba XarioXG, 7.5 Mhz linear probe, longitudinal M-mode scan (highest swipe speed) and fwEMG of gluteus medius and minimus, dynamometry were used. The onset of isometric hip abduction was measured at intensities of 20%, 40% and 60% of maximal torque. Activation onsets were correlated and patterns of onset time differences were identified. 14 volunteers were enrolled. Toshiba XarioXG, 7.5 Mhz linear probe, longitudinal M-mode scan (highest swipe speed) and fwEMG of gluteus medius and minimus, dynamometry were used. The onset of isometric hip abduction was measured at intensities of 20%, 40% and 60% of maximal torque. Activation onsets were correlated and patterns of onset time differences were identified. ResultsCorrelation of M-mode and fwEMG onsets was high (r>0.9). Motion and excitation onset differed by 5.1 ms (C.I. ±15.4 ms) and -4.1 ms (C.I. ±12.4 ms) for gluteus medius and minimus, respectively. Coincidentally, significantly different onset patterns were found for gluteus minimus of the four subjects with underlying pathology, p = 0.028 for M-mode and p = 0.042 for fwEMG, related to torque. Correlation of M-mode and fwEMG onsets was high (r>0.9). Motion and excitation onset differed by 5.1 ms (C.I. ±15.4 ms) and -4.1 ms (C.I. ±12.4 ms) for gluteus medius and minimus, respectively. Coincidentally, significantly different onset patterns were found for gluteus minimus of the four subjects with underlying pathology, p = 0.028 for M-mode and p = 0.042 for fwEMG, related to torque. ConclusionWith pathology, an altered sequence of the mechanical and electrical activation phase was found. M-mode measurements could not substitute fwEMG. However, M-mode measurements were as indicative of the functional differences as fwEMG. M-mode is a promising, non-invasive tool for assessing impaired muscle function. With pathology, an altered sequence of the mechanical and electrical activation phase was found. M-mode measurements could not substitute fwEMG. However, M-mode measurements were as indicative of the functional differences as fwEMG. M-mode is a promising, non-invasive tool for assessing impaired muscle function.