Effect of transcranial direct current stimulation on paroxysmal sympathetic hyperexcitability with acquired brain injury and cortical excitability: a randomized, double-blind, sham-controlled pilot study

Paroxysmal sympathetic hyperexcitation (PSH) refers to a clinical syndrome characterized by a sudden increase in sympathetic excitability caused by severe brain injury. This study aims to investigate the effectiveness and practicality of combining transcranial direct current stimulation (tDCS) with medication to treat PSH and employ non-linear electroencephalography (EEG) to assess changes in cortical activation post-intervention. 40 PSH patients were randomly assigned to receive either active tDCS or sham tDCS treatment over an 8-week period. The tDCS stimulation targeted the prefrontal area, left frontal-temporal-parietal cortex, right frontal-temporal-parietal cortex, and left dorsolateral prefrontal cortex. Both patient groups also underwent medication and other conventional therapies. The Paroxysmal Sympathetic Hyperactivity Assessment Measure (PSH-AM), Coma Recovery Scale-Revised (CRS-R), medication dosage, and approximate entropy (ApEn) index were assessed before and after treatment. The active tDCS group exhibited more substantial improvements in changes of PSH-AM, changes of CRS-R, and medication reduction ratios compared to the sham tDCS group after the treatment. After treatment and during follow-up, a significantly greater number of patients in the active tDCS group demonstrated clinically important differences compared to the sham tDCS group. The active tDCS group showed significantly higher ApEn indices in the less affected frontal lobe compared to the control group. No significant differences in ApEn indices were noted in the sham tDCS group before and after treatment. Regression analysis revealed that the group (active tDCS/sham tDCS) was the primary factor associated with improving PSH-AM. Therefore, we believe that in patients with PSH, combining tDCS with medication therapy demonstrated superior clinical efficacy compared to medication therapy alone. Electrophysiological results also indicated enhanced cortical excitability. Therefore, this single-center pilot study suggests that multi-target, multi-session tDCS combined with medication may be an effective treatment protocol for PSH.