Simulating tDCS-induced electric fields in stroke patients: Realistic-lesion head models are needed.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Medicine

Background:

• Transcranial direct current stimulation (tDCS) shows promise for post-stroke aphasia rehabilitation.
• Individualized tDCS simulations require accurate modeling of electric fields (E-fields).
• Stroke lesion complexity challenges the accuracy of tDCS simulations.

Purpose of the Study:

• To assess the impact of stroke lesions on tDCS-induced E-fields.
• To investigate the influence of lesion size, shape, and conductivity on E-field accuracy.
• To evaluate the necessity of realistic lesion modeling in tDCS simulations.

Main Methods:

• Analysis of structural and diffusion MRI data from stroke patients and healthy controls.
• Comparison of simulated E-fields in healthy models with and without artificial lesions.
• Evaluation of E-field differences using homogenous versus realistic lesion conductivity models.

Main Results:

• Artificial lesions altered E-field strengths by up to 47% in the region-of-interest.
• Significant variability in lesion conductivity was observed within and across patients.
• Realistic lesion models yielded small to moderate E-field differences compared to homogenous models.

Conclusions:

• Stroke lesions introduce substantial variability in tDCS-induced E-fields.
• Accurate tDCS simulations necessitate head models with realistic lesion representations (shape, size, conductivity).
• Improved simulation accuracy can guide personalized tDCS protocols for stroke rehabilitation.