Effect of transcranial direct current stimulation (tDCS) delivered via dorsolateral prefrontal cortex on central post-stroke pain and depression: a case report

Transcranial direct current stimulation (tDCS) is effective in the management of patients with central post-stroke pain (CPSP) and post-stroke depression (PSD) individually. However, it is not known if tDCS delivered via dorsolateral prefrontal cortex (DLPFC) can be used to ameliorate both symptoms.The purpose of this case report was to share the effectiveness of using tDCS of the DLPFC with short inter-session intervals to reduce central pain and depression in a stroke survivor.A 45-year-old patient presented with CPSP and depression following a stroke. The CPSP and depression were diagnosed using the Douleur Neuropathique 4 Questionnaire (DN4Q) and the Beck Depression Index (BDI) respectively. The pain score was 10 on a visual analogue scale (VAS) and it was a hemi-body burning sensation, with a score of 7 on DN4Q, and the depression score was 25 on the BDI. The patient received anodal tDCS to the left DLPFC using two different application protocols. Initially, a stimulation session of 2 milliamperes (mA) intensity for 20 minutes was given every working day for 2 weeks. After 3 weeks, she then received 7 daily sessions of periodic stimulations of 2 mA intensity for 13 minutes each with 20 minutes inter-session intervals for 1 week. The patient was followed up for 6 months post-intervention.Immediately following the last session of the initial protocol of stimulation, the BDI score reduced from 25 to 7 and the pain became abolished. However, the symptoms relapsed at 3 weeks post-intervention to the initial BDI score of 25, VAS score of 10 and DN4Q score of 7. Following the application of the second protocol of stimulation, the BDI score improved to 18 at three weeks and later to 7 at six months post-intervention while the pain (both VAS and DN4Q) became completely abolished.Further research is needed to determine if a series of periodic tDCS with short-intersession intervals applied to the DLPFC may be more effective than a single tDCS with long inter-session intervals, in decreasing pain and inducing long-term improvement in mood in people with stroke.