Transcranial direct current stimulation along with Fz-C7 montage shows a significant impact in refractory chronic cluster headache (rCCH) management, especially among the patients with low pain threshold. The condition of CCH from last < 1 month with unsubstantial remissions is referred to as refractory CCH with the high rate of severe sleeplessness and depression. As per neuroimaging examinations, ipsilateral postero-ventral hypothalamus imparts an essential role in CCH mechanism. The anterior cingulate cortex and the adjacent inferior medial frontal cortex also noticed to have increased blood flow and glucose uptake on the treatment. Various non-destructive neurostimulation techniques such as occipital nerve stimulation (ONS) used to treat rCCH efficiently but may cause severe adverse effects. Transcranial direct current stimulation (tDCS), a compact, non-invasive method is useful to activate or inhibit the underlying cerebral cortex directly by delivering low electric current to the scalp. 

The pilot trial helps to elucidate tDCS with the anode at Fz/cathode over C7 therapeutic role on pain, mood and frontal executive functions of patients suffered from rCCH. A total 31 patients went through 2mA tDCS for 20 minutes daily for 4 to 8 weeks following a 1-month baseline. Paper diaries were used to observe CH. A variation in weekly attacks among the baseline and the last week of tDCS were considered as the primary outcome. Twenty-one patients went for per-protocol analysis and 23 for modified ITT analysis. Treatment-related changes were examined in frontal lobe function and mood scales, thermal pain thresholds and nociceptive blink reflexes (nBR). After the 4 weeks of treatment, 50% responder rate noticed to be of 38% along with 35% reduction in mean weekly attack frequency when noticed via per-protocol (PP) analysis. Attack intensity and duration was also decreased considerably.