# Live Effects of Anodal and Cathodal Transcranial Direct Current Stimulation on Brain Metabolism in a Patient with Typical Hemorrhagic Stroke: A Case Study

## TL;DR

This case study explores how transcranial direct current stimulation affects brain metabolism in a stroke patient using PET scans.

## Contribution

The study demonstrates in vivo brain metabolic changes during anodal and cathodal tDCS in a post-stroke patient.

## Key findings

- Anodal tDCS increased metabolism in both the stimulated and non-stimulated hemispheres.
- Cathodal tDCS reduced metabolism in the hemisphere receiving inhibitory stimulation.
- PET imaging revealed real-time metabolic responses to tDCS in a subacute stroke patient.

## Abstract

In this study, we aimed to assess the effects of transcranial direct current stimulation (tDCS) stimulation on brain metabolism in a patient with typical hemorrhagic stroke in a subacute phase. The patient was evaluated with 18F-FDG PET (18F-fluoro-2-deoxy-D-glucose positron emission tomography) during tDCS brain stimulation at 6, 8, and 10 weeks from the event. The patient underwent the following protocol: baseline cerebral 18F-FDG-PET (T0); cerebral 18F-FDG-PET during anodal-tDCS on the affected hemisphere (T1); and cerebral 18F-FDG-PET during cathodal-tDCS on the unaffected hemisphere (T2). Baseline PET examination revealed marked hypometabolism of the right nucleo-capsular hemorrhagic lesion; at T1, an increase in brain metabolism was shown in the stimulated hemisphere and unexpectedly in the non-stimulated hemisphere; at T2, a reduction in metabolism was documented in the hemisphere ipsilateral to the inhibiting current applied by tDCS. The use of PET may provide new insights into the effects of tDCS on brain metabolism, providing in vivo information about the plasticity mechanisms of the injured brain. Further studies, using a combination of PET and tDCS, are necessary to further clarify the mechanisms of action of this stimulation technique to the clinical and functional outcomes.