A Double-Blind Comparative Study of burstDR Versus Tonic Epidural Motor Cortex Stimulation for the Treatment of Intractable Neuropathic Pain

Background: Preliminary studies on epidural motor cortex stimulation (eMCS) for the treatment of drug-resistant neuropathic pain have supported the extension to novel stimulation waveforms, in particular burstDR. However, only a low level of evidence is available. The aim of this retrospective observational study was to compare the analgesic efficacy of burstDR versus tonic eMCS.

Methods: Patients suffering from unilateral, drug-resistant neuropathic pain were selected for eMCS. During the trial phase, burstDR and tonic waveforms were successively applied for three consecutive months in a double-blinded fashion and in a random order. The primary outcome criterion was the percentage of pain relief (%PR) at 3 and 6 months. The secondary outcome criterion was the proportion of patients reporting a superior %PR with the burstDR waveform.

Results: Thirteen patients were included. The averaged %PR was 75.4% ± 18.6% after burstDR eMCS and 61.1% ± 28.6% after tonic eMCS (p = 0.21). Nine patients preferred the burstDR waveform for chronic eMCS (p = 0.16), and six of them were able to decrease or withdraw their analgesic drug intake. No adverse side effect was encountered in relation to burstDR eMCS.

Conclusions: BurstDR eMCS seems at least as effective as tonic eMCS for the treatment of drug-resistant neuropathic pain and shows a similar safety profile. Although the precise mechanisms of action remain to be fully elucidated, adequate matching between the oscillatory rhythm in the motor cortex and that of the burstDR waveform may increase synaptic efficacy, thus enhancing the functional connectivity of the motor cortex with remote brain networks involved in pain modulation.

Significance statement: In the present paper, we provide for the first time a double-blinded study comparing burstDR versus tonic eMCS for the treatment of intractable, drug-resistant neuropathic pain. Our results show that burstDR eMCS is a promising option in a population of patients especially difficult to treat, and support the ongoing move toward new stimulation waveforms able to more efficiently activate the brain networks involved in pain modulation.