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Published on: April 18, 2011
Increased threshold sural amplitude after upper limb isometric contraction in complete paraplegics
T M Tran1, F Moss, L R Robinson
1Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, Texas, USA.
Objective:
To determine whether the enhancement of threshold sural sensory nerve action potentials (SNAPs) occurred in patients with spinal cord injury after upper limb isometric contraction.
Design:
This prospective study, in which ten paraplegic patients with spinal cord injury were recruited from the Harris County community and served as his/her own control, was performed in the electromyography laboratory at Harris County Hospital District Quentin Mease Hospital. The baseline SNAP was established using ten threshold, signal-averaged stimuli to the sural nerve. With the same stimulus strength, the SNAP was recorded while the subjects' arms were pulled apart against a force gauge at 50% and 100% maximum force. Responses were recorded every 4 min until the values returned to baseline.
Results:
Results showed an increase in the SNAP amplitude after 50% and 100% maximum force. The mean preexercise SNAP amplitude was 4.0 +/- 0.6 (SE) microV. At 50% force, the SNAP amplitude was 7.57 +/- 1.2 microV; at 100% force, it was 7.29 +/- 1.2 microV. The post hoc analysis of the data revealed P = 0.009 and P = 0.01 for 50% and 100% maximum force, respectively.
Conclusions:
The threshold SNAP of the sural nerve was enhanced after isometric exercise in paraplegic patients with spinal cord injury.
