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HAND USE IMPROVED AFTER SPINAL CORD INJURY WITH NONINVASIVE STIMULATION

ScienceCodex- By using noninvasive stimulation, researchers were able to temporarily improve the ability of people with spinal cord injuries to use their hands. The findings, reported on November 29th in Current Biology, a Cell Press publication, hold promise in treating thousands of people in the United States alone who are partially paralyzed due to spinal cord injury.

“This approach builds on earlier work and highlights the importance of the corticospinal tract—which conducts impulses from the brain’s motor cortex to the spinal cord and is a major pathway contributing to voluntary movement—as an important target for intervention after spinal cord injury,” said Monica Perez of the University of Pittsburgh.

The researchers tested the new method in 19 people with chronic cervical spinal cord injury and 14 uninjured people. The treatment was customized to each individual and paired transcranial magnetic stimulation delivered to a specific part of the motor cortex with electrical stimulation to peripheral nerves found in the wrist.

One hundred paired pulses were delivered every 10 seconds for a period of around 20 minutes to produce volleys of neural activity. The timing of arrival of those volleys in the spinal cord was absolutely essential to the treatment’s success, the report shows.

“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, also of the University of Pittsburgh. “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.”

After the noninvasive treatment, the majority of the participants in the study could exert more force with their hand muscles. Those effects translated into greater manual dexterity when participants were asked to grasp and manipulate small pegs with their index fingers and thumbs.

More prolonged use of the technique or its combination with other rehabilitation strategies may well improve its therapeutic benefits, the researchers say. The protocol might also be used in the treatment of other kinds of motor disorders involving damage to the corticospinal tract.

“Human electrophysiology can be a powerful tool for developing therapies,” Perez concluded. “We need to explore new targets to improve rehabilitation strategies by taking advantage of our knowledge in human physiology and their mechanisms.”

http://www.southshoretms.com/blog/

Zapping body and brain boosts movement in paralysed

Jessica Hamzelou (New Scientist)-A single session of nerve stimulation has improved the movement of people with spinal cord injuries. Mimicking the passage of nerve signals by stimulating a muscle as well as the brain has boosted recovery and helped people to regain better control of their movements.

Voluntary movement requires a signal from the brain, which is passed down the spinal cord and then to neurons in muscles. Damage to the spinal cord can interrupt this pathway, resulting in paralysis.

To improve the control of movement in people with these injuries, Monica Perez and Karen Bunday at the University of Pittsburgh in Pennsylvania used electrical and magnetic stimulation to strengthen the connection between two nerves involved in voluntary movement of the index finger.

The pair used transcranial magnetic stimulation (TMS), a non-invasive technique in which a magnetic field alters brain activity, to target the corticospinal tract. This bundle of nerves connects movement-associated parts of the brain with the spinal cord.

“The corticospinal tract plays a major role in the recovery of motor function in spinal cord injury,” says Perez.

Just 1 to 2 milliseconds after stimulating the brain, they used an electrode to stimulate a nerve that innervates an index-finger muscle – mimicking normal brain-to-muscle nerve signalling.

Improved dexterity

Perez and Bunday tested the method on 19 people with spinal cord injuries, all of whom retained some degree of voluntary movement.

After 17 minutes of stimulation, “we saw an increase in muscle activity and force of between 20 and 40 per cent”, says Bunday.

The treatment also seemed to improve dexterity. People could place small pegs into holes about 15 per cent faster than they could before they had received the stimulation. The effect lasted for 80 minutes.

The new protocol could also enhance voluntary movement in other motor disorders affecting the corticospinal tract, such as stroke, says Perez.

Journal reference: Current Biology, DOI: 10.1016/j.cub.2012.10.046