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Effect of Antispastic Drugs on Motor Reflexes and Voluntary Muscle Contraction in Incomplete Spinal Cord Injury  Virginia Way Tong Chu, PhD, Thomas George.

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Presentation on theme: "Effect of Antispastic Drugs on Motor Reflexes and Voluntary Muscle Contraction in Incomplete Spinal Cord Injury  Virginia Way Tong Chu, PhD, Thomas George."— Presentation transcript:

1 Effect of Antispastic Drugs on Motor Reflexes and Voluntary Muscle Contraction in Incomplete Spinal Cord Injury  Virginia Way Tong Chu, PhD, Thomas George Hornby, PhD, PT, Brian David Schmit, PhD  Archives of Physical Medicine and Rehabilitation  Volume 95, Issue 4, Pages (April 2014) DOI: /j.apmr Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

2 Fig 1 Experimental setup. A custom-designed brace was constructed to hold the leg in place to measure joint torques. The brace was fitted onto the output axis of the Biodex system, which provides controlled ankle or knee movement and measurement of torque and position. The participant was placed in the sitting position for the tests. (A) Ankle brace used in the plantar flexor stretch reflex test to align the ankle to the axis of rotation of the load cell and the Biodex system. (B) Knee brace used in the isometric and isokinetic knee tests to align the knee to the axis of rotation of the load cell and the Biodex system. Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

3 Fig 2 Ankle stretch reflex results. (A) Example torque data from a typical participant are shown, triggered by 3 quick cycles of ankle dorsiflexion. Positive torque is defined as plantar flexion torque. During the holding period, plantar flexion torque was observed. (B) Typical MG EMG response to the imposed dorsiflexion was shown for a typical participant. (C, D) Ankle torque and MG EMG responses in the 10-second hold duration for all the subjects are indicated for the different drug conditions. The data shown include the means and SE for all subjects and 3 trials. Positive magnitude of torque response is ankle plantar flexion. Tizanidine significantly decreased the ankle torque and MG EMG activity compared with placebo (P<.05). Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

4 Fig 3 Knee stretch reflex results. (A–C) Knee peak flexor stretch reflex torque and flexor EMG activity for 10 subjects are indicated for different drug conditions. The data shown include the means and SEs for 10 subjects and 3 trials. Positive values indicate an increase in knee flexion torque after the administration of the drug. Baclofen significantly decreased the knee flexion torque compared with placebo (P<.001). Baclofen and tizanidine both significantly decreased HM and HL EMG activity compared with placebo (P<.05). (D–F) Knee peak extensor stretch reflex torque and extensor EMG activity for 10 subjects are indicated for different drug conditions. The data shown include the means and SEs for 10 subjects and 3 trials. Positive values indicate an increase in knee extension torque after the administration of the drug. Both baclofen and tizanidine significantly decreased knee extension torque and RF and VM EMG activity compared with placebo (P<.05). Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

5 Fig 4 Isokinetic extension results. Knee isokinetic extension torque (A) and EMG activity (B–E) for 10 subjects are indicated for different drug conditions. The data shown include the means and SEs for 10 subjects and 3 trials. Positive values indicate an increase in knee extension torque after the administration of the drug. Tizanidine and baclofen had no significant effect on the torque. Tizanidine reduced RF, HM, and HL EMG activity compared with placebo (P<.05), and baclofen reduced VM and HL EMG activity compared with placebo (P<.05). Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

6 Fig 5 Isokinetic flexion results. Knee isokinetic flexion torque (A) and EMG activity (B–E) for 10 subjects are indicated for different drug conditions. The data shown include the means and SEs for 10 subjects and 3 trials. Positive values indicate an increase in knee flexion torque after the administration of the drug. Tizanidine significantly increased the isokinetic flexion torque compared with placebo (P<.05). Tizanidine significantly decreased HM and RF EMG activity compared with placebo (P<.05), and baclofen significantly decreased HL and VM EMG activity compared with placebo (P<.05). Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions

7 Fig 6 Isometric extension and flexion results. The data shown include the means for 10 participants and 3 trials. The participants were asked to perform 5 consecutive extensions (top row) or flexion (bottom row) spaced 5 seconds apart. We observed a trend of increasing torque production with more consecutive extensions. Tizanidine and baclofen both significantly increased isometric extension torque compared with placebo (P<.05). The knee flexion torque was much lower than the knee extension torque due to the decreased strength in the knee flexors in most of the patients. Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr ) Copyright © 2014 American Congress of Rehabilitation Medicine Terms and Conditions


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