Neuronal Activity Topography Reveals Neuronal Change in Comatose Patients Treated by tDCS.

Abstract

BACKGROUND: In our hospital, transcranial direct current stimulation (tDCS) is applied in combination with occupational therapy (OT) for patients with persistent consciousness disorders. There have been reports from some research groups on Left dorsolateral prefrontal area (F3) anodal stimulation as wells as Frontal pole (Fpz) anodal stimulation under different conditions. We chose either anodal stimulation site depending on the patient's condition. CASES: Nine patients underwent tDCS with Fpz or F3 anodal stimulation for 10 days, followed by a 2-day break, after which the stimulation sites were switched, and the patients were stimulated for another 10 days. Their Electroencephalography changes were evaluated by using visual images of neuronal activity topography (NAT). The asymmetry index (AI) was also calculated to compare lateral differences in neuronal changes in the frontal lobe. Seven out of nine cases started with Fpz anode, and two with F3 anode. In the former setting, six cases improved, two aggravated and one remained unchanged. In the latter, one case unchanged and one remained aggravated. After applying tDCS, NAT and AI of the improved cases showed a tendency to approximate the normal control group. Discussion: Among these cases, all but one showed improvement in CRS-R scores, especially in Fpz stimulation. Additionally, changes in the scores indicated that most cases showed improvements in responses to visual and auditory stimulation. Furthermore, the NAT system allows for the rapid and minimally invasive assessment of changes in neuronal activity. Consequently, it is suggested that this system may be valuable for evaluating the therapeutic effects of tDCS and identifying effective stimulation sites.