TY - GEN
T1 - Characterization of the tendon vibration reflex response in hemi-spastic stroke individuals
AU - Suresh, Nina L.
AU - Wang, Inga
AU - Heckman, C. J.
AU - Rymer, W. Zev
PY - 2011
Y1 - 2011
N2 - The objective of our study was to assess the role of persistent inward currents, or PICs, on the excitability of motoneurons innervating spastic muscle in hemi-spastic stroke individuals. This was accomplished by examining the effects of tonic vibration applied to the tendon of the biceps brachii muscle. The elicited TVR (tonic vibration reflex) provides a useful way to assess the degree of excitability of spinal neurons in spastic syndromes, and it has additional features that may signify the presence of PICs in spastic motoneurons. We applied sinusoidal stretches of varied duration to the biceps tendon of two hemi-spastic stroke individuals and one neurologically intact individual. We recorded the resulting TVR response from electromyographic(EMG) signals obtained from the biceps as well as force recorded at the wrist. The results of our preliminary study show that the initial rise of the TVR force response as well as the force magnitude are generally greater in spastic muscle, perhaps a marker of motoneuron excitability. Additionally, a shorter vibration duration was sufficient to evoke a response on the spastic side of our tested stroke subjects. However, the key marker of PICs the decay of the force response as well as sustained after-discharge did not exhibit clear differences. Our present data suggests that motoneurons innervating spastic muscle are more readily activated, and thus exhibit increased excitability, which could possibly be a function of greater depolarization, without a change in PIC magnitude. Our data does not rule out the possibility of subthreshold activation of the PIC resulting in enhanced motoneuron depolarization.
AB - The objective of our study was to assess the role of persistent inward currents, or PICs, on the excitability of motoneurons innervating spastic muscle in hemi-spastic stroke individuals. This was accomplished by examining the effects of tonic vibration applied to the tendon of the biceps brachii muscle. The elicited TVR (tonic vibration reflex) provides a useful way to assess the degree of excitability of spinal neurons in spastic syndromes, and it has additional features that may signify the presence of PICs in spastic motoneurons. We applied sinusoidal stretches of varied duration to the biceps tendon of two hemi-spastic stroke individuals and one neurologically intact individual. We recorded the resulting TVR response from electromyographic(EMG) signals obtained from the biceps as well as force recorded at the wrist. The results of our preliminary study show that the initial rise of the TVR force response as well as the force magnitude are generally greater in spastic muscle, perhaps a marker of motoneuron excitability. Additionally, a shorter vibration duration was sufficient to evoke a response on the spastic side of our tested stroke subjects. However, the key marker of PICs the decay of the force response as well as sustained after-discharge did not exhibit clear differences. Our present data suggests that motoneurons innervating spastic muscle are more readily activated, and thus exhibit increased excitability, which could possibly be a function of greater depolarization, without a change in PIC magnitude. Our data does not rule out the possibility of subthreshold activation of the PIC resulting in enhanced motoneuron depolarization.
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U2 - 10.1109/IEMBS.2011.6090379
DO - 10.1109/IEMBS.2011.6090379
M3 - Conference contribution
C2 - 22254740
AN - SCOPUS:84862242435
SN - 9781424441211
T3 - Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS
SP - 2053
EP - 2056
BT - 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2011
T2 - 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2011
Y2 - 30 August 2011 through 3 September 2011
ER -