December 16, 2018

Non-invasive brain stimulation in dystonia

There is a very interesting review by Erro et al. entitled “non-invasive brain stimulation for dystonia: therapeutic implication” that I would like to draw to your attention.
Currently, there are two forms of non-invasive brain stimulation (NIBS). The first technique is called (1) transcranial magnetic stimulation (TMS) and the second one (2) transcranial current stimulation (tCS). The term “non-invasive” is used to underline the fact that magnetic stimulation is administered without the necessity of surgical intervention (in contrast to deep brain stimulation). The basic principle is that those methods are designed to modulate the function of brain systems, specifically cortical-subcortical network with magnetic pulses. Even though the treatment is non-invasive, some side effects were observed.

Repetitive transcranial magnetic stimulation (rTMS) Repetitive TMS is a technique of electromagnetic induction of a small, cortical target in the brain. The magnetic field generator, so called “coil” (i.e figure-of-eight shaped), is held next to the scalp. The magnetic field passes the skin and skull inducing a weak current in the cerebral cortex, located below the area of application. Neuromodulatory effect depends on frequency and pattern of stimulation, namely length, form and intensity of magnetic pulses. The effect of rTMS is to change the function of targeted
brain area and indirectly assess the brain neuroplasticity. Theta burst stimulation (TBS) is an alternative method of TMS which is said to be more efficient. Two types of TBS are available: continuous TBS (cTBS), which incorporates an uninterrupted train of stimulation for short time (20s or 40s) and intermittent TBS (iTBS) with brief (2s) train delivered every 10 seconds. It’s worth noting that the response for the treatment may vary between the patients. One of the potential causes of this inter-individual variability may be the genetic polymorphisms.