What is Noninvasive Brain Therapy?

Neuropsychiatry advances with the use of trans-cranial stimulation.

The use of noninvasive brain stimulation in modern neuropsychiatry had its beginnings in the last century, with electroconvulsive therapy (ECT), which, in the forties and fifties  became the main therapeutic intervention for various mental illnesses. Nevertheless, the introduction of psychotropic drugs in the second half of the twentieth century lowered the ECT and interest in using other forms of "physical" or "biological" therapies.

But this situation has changed in recent decades. Both in the psychiatry field as in neurology, the use of drugs has reached a plateau, either in terms of efficacy or in side effects. In this context, the renewed use of brain stimulation therapies, particularly those known as "non-invasive" means that are associated with little or no side effects; moreover, the same action allows a more focused, towards the brain that is hypo-or hyper-functioning area. The noninvasive brain stimulation advancement thus appeared in the wake of advances in neuroscience and neuroimaging, with a greater understanding of the pathophysiological mechanisms of neuropsychiatric disorders.

Currently, there are two techniques that best represent the non-invasive brain stimulation: a trans-cranial magnetic stimulation (TMS) and trans-cranial direct current stimulation (tDCS). Both techniques are noninvasive, virtually free of side effects and their effects are focused, that is, their effects are limited to the brain area desired to stimulate or inhibit, without affecting other brain area regions.

Trans-cranial Magnetic Stimulation (TMS) [not available yet]

The TMS was discovered in the mid-1980s, becoming studied in patients about ten years later. TMS uses an electric current of high intensity, by passing through a coil that has the shape of "8" generates a magnetic field of high intensity. The coil, when placed on the skull, generates a magnetic field that passes through the barrier bone, resulting an electric current in the brain. Unlike an MRI that magnetic field fluctuates (that is, alternating polarity) at the rate of 1 to 20 times per second. This causes "slow" pulse (less than 1-5 times per second) or "fast" (above 5 times per second) are generated. Roughly, slow pulse decrease the brain activity rapid pulse enhance the brain region activity.

Trans-cranial direct current stimulation (tDCS)

The ETCC was studied briefly in the 1960s, and was subsequently abandoned. In the first decade of this century, however, was investigated again. The ETCC uses a power source of 27V-3V and generates a continuous low-intensity electrical current (1-2mA). The device has an anode and a cathode, which are placed on the scalp areas that respectively want to stimulate or inhibit. The ETCC is still being extensively studied for the treatment of neuropsychiatric disorders.

Collateral effects

An important aspect of noninvasive neurostimulation concerns security. Short term adverse effects are minimal and restricted to the period of stimulation.

TMS may irritate and cause painful sensations on the skin surface, as the superficial sensory nerves of the skin can also be stimulated. Similarly, stimulation of the peripheral motor nerves can lead to small spasms. But these effects are transient and many people who have been using these techniques have reported getting used to those spasms; cease to feel them after a few days of treatment.

The tDCS can produce skin irritation with redness, by skin peripheral stimulation, but it does not lead to motor spasms or pain. The most severe ever reported acute side effect consisted of a seizure associated with EMT, but this happened in a few patients, who were already suffering from epilepsy or were under experimental protocols that used TMS in high doses. Long-term side effects have not been described so far, unlike reported to the ECT, which is associated with some amnesic disorders. On the contrary, initial studies in healthy volunteers have demonstrated even an improvement after the use of tDCS in attention and memory tests.

Application

The treatment with non-invasive brain stimulation involves technique daily applications for periods of 20 minutes to over 2 to 4 weeks, or for 10 to 20 days. After this period of acute treatment, it is recommended general maintenance treatment, which may range from 2 times per week to 2 times per month.

To whom serves Stimulation with DC?

The tDCS can be used in the treatment of many diseases, among which painful syndromes (fibromyalgia, headache, trigeminal neuralgia, neuralgia), tinnitus (ringing), ischemic stroke sequelae (spasticity, aphasia, rehabilitation), vascular disorders, mood (depression and bipolar affective disorder), anxiety disorders and movement disorders.

New indications for the ETCC are still being investigated in many parts of the world.