Transcranial magnetic stimulation
The brain is a good insulator and high voltage electricity is required to reach the brain through the skull. But magnets can reach the brain through the skull. How this works can be understood with the help of the following example. Magnets when held below the wooden table top can move the pins placed on the surface. Similarly magnets are powerful enough to alter the neurons through the skull. But to affect the neurons a lot of magnetic force is required. And this force has to be changed very quickly. The first TMS machine was capable of delivering a pulse every three seconds. Now machines are available that can deliver 50 stimuli per second. As the magnetic stimulations are delivered at specific intervals it is called repetitive transcranial magnetic stimulation (rTMS.) It is a new method that promises to be effective for depression. Currently more than 1000 TMS stimulators are in use and more than 3000 journals have been published regarding its usage.
Working of TMS
This is a non invasive method to excite the neurons in the brain. Weak electric currents that are passed trigger the brain activity without the need of surgery or electrodes. Electro magnetic theory works by just placing a coil on the skull. Even direct contact is not required. The shape of the hand held coil varies according to the size of the field. The coil is driven by a machine which supplies the large current that is necessary at the rate of 50 stimuli per second in the case of rTMS.
Technical developments have taken place in the devices of TMS making it possible for rTMS to be applied in trains of multiple stimuli. This allows for a variation to be brought about in the strength of the stimuli, the duration between the stimuli, the total number of stimuli or the area where the stimuli can be given can also be varied.
Uses of rTMS
- Apart from depression and voice hallucinations TMS can be used to treat migraines; it can prevent migraines before the symptoms make a full blown appearance.
- TMS is useful in medical science for it helps in the study of brain activity. It indicates which areas are associated with short term memory or feelings of depression, etc. If these regions are interfered with via TMS then it affects the subjects’ ability to perform those tasks.
- TMS can be beneficially put to use by enhancing certain mental skills and abilities. This property of TMS is still subject to research and it may take time before the findings are put to effective use.
- Being non invasive it is totally free of side effects.
The benefits of TMS are not yet substantiated by proof based on solid ground. But some cases that were treated by ECT can be replaced by TMS especially the treatment for depression. It would be a great boon for the sufferer to have a painless treatment free of side effects.