Transcranial Magnetic Stimulation May Aid in Stroke Rehabilitation

Repetitive transcranial magnetic stimulation (rTMS) can alter brain activity and may help patients regain motor control after stroke.

rTMS is a non-invasive technique used to induce electrical activity in the surface of the brain (cortex) and influence brain activity.[1] Electrodes are not used and sedation is not required.

rTMS is used to assess neurological function. It is being studied as a potential treatment for depression and neurological disorders, and is now under investigation for use in stroke rehabilitation.

The Procedure

A fluctuating magnetic field is created by passing a precisely controlled alternating electric current through a copper coil contained in an insulated wand. When placed near the head, the field induces electrical activity in the cortex. Low frequency currents (<1 Hz) decrease activity and higher frequencies increase it.[1] Treatment frequency and length are unknown.

Stroke Rehabilitation

Between 40,000 and 50,000 Canadians have strokes each year, and it is the number one cause of disability in Canadian adults.[2] Stroke can impair movement and leave patients dependent on others to perform routine daily tasks.

Proposed Mechanism

There is evidence that the application of rTMS to the motor cortex modulates the inter-hemispheric connections between each half of the brain and may improve some movement disorders caused by stroke.[3]

Evidence Related to Stroke

Several small investigational studies have shown functional gains with statistically significant results.

In one study, where an operator went through the motions of treatment without actually performing it in a “sham”-controlled group, eight stroke patients showed decreased reaction time and improved motor performance when they received rTMS (1 Hz) to the undamaged hemisphere, but not when they received sham stimulation.[4]

A controlled, single-blind study found that the application of rTMS (10 Hz) to the damaged hemisphere of 15 stroke patients resulted in faster, more accurate finger movement when compared with sham stimulation.[5]

In a randomized controlled trial, 26 stroke patients received rTMS (3 Hz) and 26 received sham stimulation to the undamaged hemisphere in addition to normal therapy. The rTMS group showed greater improvement on three disability scales.[6]

In a double-blind study, 20 patients who received rTMS (1 Hz) to the undamaged hemisphere showed improvement in the affected hand compared with a group that received sham stimulation.[3]

Regulatory Status

The Magstim Rapid² stimulator (Magstim Ltd., Wales, UK) is a commercial device that delivers rTMS. The Magstim Rapid² stimulator received Health Canada licensing in November 2005 for the assessment of neurological and muscular function.

Cost

According to the manufacturer, the Magstim Rapid² stimulator costs C$44,000. In addition, the coil (which typically lasts two years) costs approximately C$5,000. No disposable products are required and operator training is minimal.

References

[1] Alisauskiene M, et al. Medicina (Kaunas) 2005;41(10):813-24. Available: http://medicina.kmu.lt/0510/0510-01e.pdf

[2] Heart and Stroke Foundation of Canada. Stroke statistics. Ottawa: The Foundation; 2002. Available: http://ww2.heartandstroke.ca/Page.asp?PageID=33&ArticleID=1078&Src=news&From=SubCategory

[3] Takeuchi N, et al. Stroke 2005;36(12):2681-6.

[4] Mansur CG, et al. Neurology 2005;64(10):1802-4.

[5] Kim YH, et al. Stroke 2006;37(6):1471-6.

[6] Khedr EM, et al. Neurology 2005;65(3):466-8.