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December 28, 2012

Transcranial stimulation improves symptoms of Tourette’s

Helen Albert, Senior medwireNews Reporter (Dec. 18, 2012)-A month of daily transcranial magnetic stimulation targeting the supplemental motor area (SMA) results in lasting improvements in symptoms of Tourette syndrome, show study findings.

“Repetitive transcranial magnetic stimulation (rTMS)… involves repetitive generation of a brief, powerful magnetic field by a small coil positioned over the scalp that induces an electric current in the brain,” explain Nong Xiao (Chongqing Medical University, Yuzhong district, China) and colleagues.

The technique is designed as a noninvasive treatment for a range of neurological and psychiatric disorders including migraine, stroke, and Parkinson’s disease.

In this study, the researchers tested the capacity of low-frequency 1 Hz rTMS applied at 20 daily sessions (Monday-Friday) over 4 weeks for treatment of the motor and speech neurological tics displayed by patients with Tourette syndrome, on the basis that low-frequency rTMS (≤1 Hz) inhibits and high-frequency rTMS (>5 Hz) promotes cortical excitability.

In total, 25 children under 16 years took part in the study. After 4 weeks of treatment, the team observed no improvements in tic symptoms in six children, but significant improvements in these symptoms that lasted until 3 months in 19 children, and until 6 months in 17 children (68%).

On average, significant reductions were seen in the scores obtained on various tests by the children at 4 weeks compared with baseline. These included the Yale Global Tic Severity Scale; Clinical Global Impression Scale; Swanson, Nolan and Pelham Rating Scale, version IV for attention-defict hyperactivity disorder (SNAP-IV); Children’s Depression Inventory; Spence Children’s Anxiety Scale; and a novel Attention Test.

Overall scores for all these tests were lower at 6 months than at baseline, but only the SNAP-IV and Attention test scores were significantly lower at 6 months than at 4 weeks.

“Low-frequency (1 Hz) rTMS to the SMA significantly improved Tourette syndrome symptoms, suggesting that it is effective on tics, hyperactivity, attention deficit, depression and anxiety in children with Tourette syndrome,” write Xiao and co-workers in the Journal of Clinical Neuroscience.

“These collective results suggest the need for further studies using rTMS as a research and clinical therapeutic tool in psychiatric and neurological diseases, with particular attention to patients with Tourette syndrome.”

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