No abstract

No abstract

Results from this pilot feasibility study suggest that tDCS may be able to reduce post-TKA opioid requirements. Although these results are preliminary, the data support further research in the area of adjunctive cortical stimulation in the management of postsurgical pain.

Background Pain is often a complaint that precedes total knee arthroplasty (TKA), however the procedure itself is associated with considerable post-operative pain lasting days to weeks which can predict longer-term surgical outcomes. Previously, we reported significant opioid-sparing effects of motor cortex transcranial direct current stimulation from a single-blind trial. In the present study, we used double-blind methodology to compare motor cortex tDCS and prefrontal cortex tDCS to both sham and active-control (active electrodes over non-pain modulating brain areas) tDCS. Methods 58 patients undergoing unilateral TKA were randomly assigned to receive 4 20-minute sessions (a total of 80 minutes) of tDCS (2mA) post-surgery with electrodes placed to create 4 groups: 1) MOTOR (n=14); anode-motor/cathode-right prefrontal, 2) PREFRONTAL (n=16); anode-left-prefrontal/cathode-right-sensory, 3) ACTIVE-CONTROL (n=15); anode-left-temporal-occipital junction/cathode-medial-anterior-premotor-area, and 4) SHAM (n=13); 0mA-current stimulation using placements 1 or 2. Patient controlled analgesia (PCA; hydromorphone) use was tracked during the ∼72-hours post-surgery. Results Patients in the sham group and the active-control group used 15.4mg (SD=14.1) and 16.0mg (SD=9.7) of PCA hydromorphone respectively. There was no difference between the slopes of the cumulative PCA usage curves between these two groups (p=.25; ns). Patients in the prefrontal tDCS group used an average of 11.7mg (SD=5.0) of PCA hydromporhone, and the slope of the cumulative PCA usage curve was significantly lower than sham (p<.0001). However, patients in the motor tDCS group used an average of 19.6mg (SD=11.9) hydromorphone and the slope of the PCA use curve was significantly higher than sham (p<.0001). Conclusions Results from this double-blind cortical-target-optimization study suggest that anodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex may be a reasonable approach to reducing post-TKA opioid requirements. Given the unexpected finding that motor cortex failed to produce an opioid sparing effect in this follow-up trial, further research in the area of post-operative cortical stimulation is still needed.