Magnetic Stimulation Improves Spinal Cord Injury

Precisely timed noninvasive nerve stimulation in patients with spinal cord injuries improved their ability to use their hands, according to a new study.

Researchers from the University of Pittsburgh (PA, USA) conducted a study involving 19 people with a cervical spinal cord injury and 14 age-matched healthy controls, who underwent transcranial magnetic stimulation to the hand representation of the motor cortex to examine spike-timing dependent plasticity (STDP). The signals were paired with signals derived from peripheral nerve stimulation of the ulnar nerve at the wrist. To have an effect, the signals from the brain had to reach the corticospinal-motoneuronal synapses of the first dorsal interosseous muscle 1-2 milliseconds before those from the ulnar nerve.


The study participants were given 100 paired pulses every 10 seconds for about 20 minutes, and then they were asked to exert force with the index finger and to perform a dexterity task, the so-called nine-hole peg test, in which they were asked to use the thumb and index finger to remove pegs from holes, set them aside, and then pick them up again and replace them. The researchers found that the stimulation process increased the force the injured participants could produce by about 20% over baseline within the first 20 minutes; and the average time it took for injured participants to complete the peg test fell by about 15% within the first 30 minutes. The study was published on November 29, 2012, in Current Biology.

“This short, noninvasive stimulation protocol has the potential to be used within a clinic setting as part of a rehabilitation technique,” said study coauthor Karen Bunday, PhD. “When pulses from the motor cortex were precisely timed to arrive at the spinal cord one or two milliseconds before pulses from the peripheral nerve, we observed an increase in spinal cord transmission and voluntary motor output for up to 80 minutes.”

The corticospinal tract conducts nerve signals from the brain's motor cortex to the spinal cord and plays a major role in voluntary movement.

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