1000 Section - Towards a stratified approach towards noninvasive brain stimulation for stroke motor recovery - preliminary results

To compare the effectiveness of various noninvasive brain stimulation (NIBS) protocols (transcranial direct stimulation (tDCS) and transcranial magnetic stimulation (rTMS)) in improving upper limb outcomes post-stroke.


Design:

This was a non-randomised trial. Participants 21-80 years old who suffered a stroke ≥3 months prior resulting in upper limb impairment with SAFE score < 8, were recruited to undergo NIBS with conventional therapy. Matched controls underwent conventional therapy. Outcomes included the Fugl Meyer Assessment (FMA) and cortical excitability measures using TMS collected before, after, and 6 weeks post-intervention. NIBS included 1 Hz rTMS to contralesional M1 (cM1), anodal tDCS or intermittent theta-burst stimulation (iTBS) to ipsilesional M1, anodal tDCS or 10Hz rTMS to contralesional dorsal premotor cortex (cPMD).


Results:

32 participants 3-27 months post-stroke participated. 20 underwent NIBS, 12 were controls. 19 had undetectable MEP in the stroke-affected hand at baseline (MEP-, 11 intervention, 8 controls), 13 had detectable MEPs (MEP+, 9 intervention, 3 controls). Proportional recovery post-intervention (=delta FMA/(66-baseline FMA)) was highest with anodal tDCS to cPMD for both MEP+ and MEP- (15.5%±1.1%; 21.8%±26.1% respectively) and at 6 weeks (17.3%±7.3%; 22.7±25.6%) vs controls (4.7%±12.7%; 11.8%±9.9%), and at 6 weeks (6.7%±19.9%; 15.2%±3.8%). Attempted iM1 facilitation with anodal tDCS or iTBS gave insignificant improvement in both groups (3.5%±6.1% in MEP-, 2.4%±5.3% in MEP+) while attempted inhibition of cM1 with 1Hz rTMS gave greater improvement in MEP+ (31.7%±2.4%) compared to MEP- (9.7%).


Conclusion:

Mixed results reported with NIBS for stroke recovery may be due to lack of patient stratification.  Our results suggest that anodal tDCS to cPMD is promising for MEP+ and MEP- patients. Attempted facilitation of iM1 with anodal tDCS or iTBS appears ineffective. Attempted inhibition of cM1 with 1Hz rTMS appears more effective for MEP+ than MEP-. These results need to be confirmed and mechanisms elucidated in larger randomised controlled trials.