Abstract
Introduction: Spinal cord stimulation (SCS) is routinely used to treat medically intractable pain. Different stimulation designs exist for pain suppression. Among these, both high-frequency stimulation at 10 kHz and burst stimulation are paresthesia-free, and it has been postulated, based on theoretical and clinical grounds, that they may be fundamentally the same, i.e., that both modulate the medial ‘suffering’ pathway rather than tonic stimulation. Yet no proof exists for this proposal.
Materials and Methods: Clinical and electroencephalographic (EEG) data from 10 patients undergoing both burst with passive recharge and 10kHz SCS for 10 days are analyzed to examine the commonalities and differences between burst and 10kHz stimulation. A source localized (sLORETA) EEG subtraction and conjunction analysis is performed in each condition.
Results: Burst and 10kHz significantly reduced leg pain to a similar extent. For back pain, burst showed a significant reduction from baseline, whereas 10kHz did not; however, the direct comparison between burst and 10kHz was not significant. Brain differences were observed in alpha-band activity within medial cingulate and operculo-insular regions during burst relative to 10kHz, while both paradigms shared beta activity with a peak in the pregenual anterior cingulate region. Given the 19-channel montage, these anatomical assignments should be interpreted cautiously. Burst and 10kHz stimulation share beta activation in the pregenual anterior cingulate cortex (pgACC). The common pgACC activation correlates with the degree of pain suppression in both the back and the legs. The dACC deactivation correlates with back pain reduction in burst. For 10kHz, there is no significant correlation.
Discussion and conclusion: These data suggest that burst and 10kHz stimulation both modulate the descending pain-inhibitory system (via pgACC), thereby decreasing both back and leg pain. Burst also modulates the dACC, sgACC, and insula, which correlate with changes in back pain.