Burst and 10 kHz Spinal Cord Stimulation: Different and Common Brain Mechanisms

Spinal cord stimulation 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, on the basis of theoretical and clinical grounds, that they may be fundamentally the same, ie, that both modulate the medial "suffering" pathway rather thantonic stimulation; yet no proof exists for this proposal.

Clinical and electroencephalographic (EEG) data from ten patients undergoing both burst with passive recharge and 10 kHz spinal cord stimulation for ten days are analyzed to examine the commonalities and differences between burst and 10 kHz stimulation. A source localized (standardized low-resolution brain electromagnetic tomography) EEG subtraction and conjunction analysis is performed in each condition.

Burst and 10 kHz significantly reduced leg pain to a similar extent. For back pain, burst showed a substantial reduction from baseline, whereas 10 kHz did not; however, the direct comparison between burst and 10 kHz was not significant. Brain differences were observed in alpha-band activity within medial cingulate and operculo-insular regions during burst relative to 10 kHz, whereas both paradigms shared beta activity with a peak in the pregenual anterior cingulate region. Given the 19-channel montage, these anatomic assignments should be interpreted cautiously. Burst and 10 kHz 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 dorsal anterior cingulate cortex deactivation correlates with back pain reduction in burst. For 10 kHz, there is no significant correlation.

These data suggest that burst and 10 kHz stimulation both modulate the descending pain-inhibitory system (through pgACC), thereby decreasing both back and leg pain. Burst also modulates the dorsal anterior cingulate cortex, subgenual anterior cingulate cortex, and insula, which correlate with changes in back pain.