Randomized, sham controlled trial of transcranial direct current stimulation for painful diabetic polyneuropathy.
OBJECTIVE
To investigate the analgesic effect of transcranial direct current stimulation (tDCS) over the primary motor (M1), dorsolateral prefrontal cortex (DLPFC), and sham tDCS in patients with painful diabetic polyneuropathy (PDPN).


METHODS
Patients with PDPN (n=60) were divided randomly into the three groups (n=20 per group). Each group received anodal tDCS with the anode centered over the left M1, DLPFC, or sham stimulation for 20 minutes at intensity of 2 mA for 5 consecutive days. A blinded physician rated the patients' pain using a visual analog scale (VAS), Clinical Global Impression (CGI) score, anxiety score, sleep quality, Beck Depression Inventory (BDI), and the pain threshold (PT) to pressure.


RESULTS
After the tDCS sessions, the M1 group showed a significantly greater reduction in VAS for pain and PT versus the sham and DLPFC groups (p<0.001). The reduction in VAS for pain was sustained after 2 and 4 weeks of follow-up in the M1 group compared with the sham group (p<0.001, p=0.007). Significant differences were observed among the three groups over time in VAS for pain (p<0.001), CGI score (p=0.01), and PT (p<0.001). No significant difference was observed among the groups in sleep quality, anxiety score, or BDI score immediately after tDCS.


CONCLUSIONS
Five daily sessions of tDCS over the M1 can produce immediate pain relief, and relief 2- and 4-week in duration in patients with PDPN. Our findings provide the first evidence of a beneficial effect of tDCS on PDPN.
Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Yon Joon
YJ
Kim
Department of Biomedical Engineering, Keimyung University, Daegu, Korea.
Jeonghun
J
Ku
Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Hyun Jung
HJ
Kim
Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Dal Jae
DJ
Im
Department of Biostatistics, Yonsei University College of Medicine, Seoul, Korea.
Hye Sun
HS
Lee
Department of Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Kyung Ah
KA
Han
Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
Youn Joo
YJ
Kang
Chronic pain; Diabetic neuropathy; Transcranial direct current stimulation