State-of-art for (HD)-tDCS Migraine/Pain Control and Model Based Target Analysis

Objectives: Even though recent tDCS (transcranial direct current stimulation) studies promise to modulate specific cortical regions associated with the pain perception and suffering, the electric current produced usually spreads beyond the area of the electrodes placement. Our study sought to accurately compare the neuroanatomic location and strength of the predicted electric current peaks induced by the high-definition (HD) and conventional tDCS montages developed for migraine and other chronic pain disorders trials, at cortical and subcortical levels.
Methods: Using a forward-model analysis, we examined the neuroanatomical anodal-cathodal current distribution of conventional tDCS motor cortex-supra orbital (M1-SO), dorsolateral prefrontal cortex bilateral (F3-F4) and occipital cortex-vertex (OZ-CZ) montages, as well as 4x1 and 2X2 HD-tDCS montages.
Results: The results revealed that M1SO produces a large current flow in the frontal cortex and neighboring cortical areas, including the dorsolateral and ventrolateral prefrontal cortex as well as the premotor cortex. Interestingly, peaks of current flow also occur in deeper brain structures such as cingulate cortex, insula, thalamus and brainstem. The same structures also receive significant amount of current when the Oz-CZ and F3-F4 montages are applied. However, differences occur in the outer cortical regions stimulated. The visual cortex receives the majority of the current flow with the OZ-CZ setup, while the anterior parts of the superior and middle frontal gyri display an intense amount of current with F3F4.
Conclusions: This study provides novel information regarding the neuroanatomical distribution of the electrical current using several forms of tDCS montage available for pain control. The differential cortical/subcortical activation observed, suggests that the tDCS electrode positioning can be specifically tailored to treat each chronic pain disorder.