Percutaneous occipital nerve stimulation (ONS) is a useful approach in the treatment of refractory chronic cluster headache (rCCH). Responders to ONS vary from non-responders by higher glucose metabolism in subgenual anterior cingulate cortex (sgACC). The study demonstrated that direct current stimulation (tDCS) might be capable of stimulating this area and consequently can improve rCCH patients state. The purpose of the analysis was to examine the therapeutic potential of tDCS and associated potential influences on frontal executive functions, mood, and pain perception in rCCH patients.

A total of 31 patients were invited to implement daily 20-min sittings of 2 mA tDCS for 4 or 8 weeks following a 1-month baseline. Paper diaries were used to observe CH attacks. There was a change observed in primary outcome measures in weekly attacks between baseline and the last week of tDCS. For a modified ITT and protocol analysis, a total of 23 and 21 patients were involved, respectively. The treatment-related changes in frontal lobe function, mood and thermal pain thresholds and nociceptive blink reflexes (nBR) scales were also examined.

A mean 35% decline in attack incidence with 41% of patients with a ≥ 50% reduction was noticed in the per-protocol analysis. The attack severity and duration were also decreased considerably.  The 50% responder rate noticed to be 45% after 8 weeks. However, the mean attack incidence had reversed to baseline levels at the follow-up 2 weeks after tDCS. The patients with high baseline thermal pain thresholds in the forehead showed a significant treatment effect. An increase was seen in the Frontal Assessment Battery score. Whereas, depression scores or nBR showed no variations. 

tDCS with an Fz-C7 montage presents as a preventive approach in rCCH patients, particularly those with low pain responsiveness, proposing that a sham-controlled examination in a cluster headache is essential. Further analysis is still needed to determine whether the therapeutic impact is due to sgACC activation or of other prefrontal cortical.