Ann Rehabil Med.  2013 Dec;37(6):766-776. 10.5535/arm.2013.37.6.766.

Randomized, Sham Controlled Trial of Transcranial Direct Current Stimulation for Painful Diabetic Polyneuropathy

• Kim YJ
• Ku J
• Kim HJ
• Im DJ
• Lee HS
• Han KA
• Kang YJ

• KMID: 2266555
• DOI: http://doi.org/10.5535/arm.2013.37.6.766

Abstract

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.
CONCLUSION
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.

Keyword

Transcranial direct current stimulation; Chronic pain; Diabetic neuropathy

MeSH Terms

Anxiety
Chronic Pain
Depression
Diabetic Neuropathies*
Electrodes
Follow-Up Studies
Humans
Pain Threshold
Prefrontal Cortex
Visual Analog Scale

Figure

• 

  Fig. 1 Patient flow diagram. Twelve patients withdrew from the study: seven had early discharge during stimulation sessions and five withdrew after the third session of stimulation because of poor cooperation (n=4) or headache (n=1). PDPN, painful diabetic polyneuropathy; BDI, Beck Depression Index; MMSE, Mini-Mental State Examination; VAS, visual analog scale; PT, pain threshold; CGI, Clinical Global Impression; tDCS, transcranial direct current stimulation; M1, primary motor cortex; DLPFC, dorsolateral prefrontal cortex.

• 

  Fig. 2 Anodal tDCS. The anode was positioned over the M1 or DLPFC and the cathode over the contralateral supraorbital region (2 mA for 20 minutes on 5 consecutive days). tDCS, transcranial direct current stimulation; M1, primary motor cortex; DLPFC, dorsolateral prefrontal cortex.

• 

  Fig. 3 After 5 consecutive days of tDCS sessions over M1, pain reduction was significantly greater compared with the sham and DLPFC groups (***p<0.001) and compared with the sham group, its analgesic effect was sustained after 2 weeks (***p<0.001) and 4 weeks (**p<0.01) of follow-up. Likewise, the M1 group showed greater pain reduction than the DLPFC group (**p<0.01) after 2 weeks. tDCS, transcranial direct current stimulation; M1, primary motor cortex; DLPFC, left dorsolateral prefrontal cortex; VAS, visual analog scale.

• 

  Fig. 4 After 5 consecutive days of tDCS sessions, the M1 group exhibited a significantly greater reduction in CGI score (***p<0.001), which was decreased significantly after 2 and 4 weeks of follow-up compared with the sham group (*p=0.02, **p=0.008). CGI is rated on a 7-point scale: 1, normal, not ill at all; 2, borderline mentally ill; 3, mildly ill; 4, moderately ill; 5, markedly ill; 6, severely ill; 7, most severely ill. tDCS, transcranial direct current stimulation; M1, primary motor cortex; DLPFC, left dorsolateral prefrontal cortex; CGI, Clinical Global Impression.

• 

  Fig. 5 After 5 consecutive days of tDCS sessions, the M1 group exhibited a significantly greater increase in pain threshold compared with the sham and DLPFC groups (***p<0.001). tDCS, transcranial direct current stimulation; M1, primary motor cortex; DLPFC, left dorsolateral prefrontal cortex.

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