Neuromodulation : journal of the International Neuromodulation Society
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The physiological mechanisms behind the therapeutic effects of spinal cord stimulation (SCS) are only partially understood. Our aim was to perform a literature review of studies that used objective measures to characterize mechanisms of action of SCS in neuropathic pain patients. ⋯ SCS appears to modulate pain via spinal and/or supraspinal mechanisms of action (e.g., pain gating, descending pain inhibition). However, to better understand the mechanisms of action of SCS, we believe that it is necessary to carry out systematic, controlled, and well-powered studies using objective patient measures. To optimize the clinical effectiveness of SCS for neuropathic pain, we also believe that it is necessary to develop and implement patient-specific approaches.
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Intraoperative neuromonitoring for spinal cord stimulation uses electromyography (EMG) responses to determine myotomal coverage as a marker for dermatomal coverage. These responses are utilized to determine the orientation of the electrode. Somatosensory evoked potential (SSEP) collision testing can also be used in which sensory signals are decreased and/or eliminated when stimulation is activated. ⋯ This observational series demonstrated distinct differences between the waveforms and stimulation alluding to different mechanisms of action. Nevro high-frequency and Abbott BurstDR waveforms appear to be most different in action from traditional tonic stimulation while Abbotts BurstDR appears to be the most energy efficient generating signals at the lowest thresholds with a propagating effect that leads to a hyperexcitable or primed stimulation state.
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Spinal cord stimulation (SCS) represents an important neurostimulation therapy for pain. A new ultra-high frequency (10,000 Hz) SCS paradigm has shown improved pain relief without eliciting paresthesia. We aim to determine whether sub-sensory threshold SCS of lower frequencies also can inhibit mechanical hypersensitivity in nerve-injured rats and examine how electric charge delivery of stimulation may affect pain inhibition by different patterns of subthreshold SCS. ⋯ Inhibition of neuropathic mechanical hypersensitivity can be achieved with low-frequency subthreshold SCS by optimizing the electric charge delivery, which may affect the effect of SCS in individual animals.
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Preoperative work-up for spinal cord stimulation (SCS) includes a psychological assessment; however, no one psychological factor has correlated with poor outcomes across studies. We developed a Psychological Evaluation Tool for Spinal Cord Stimulation Candidacy (PETSCSC), which includes all factors in the literature found to correlate with outcomes. In this study, we examine whether PETSCSC correlates with postoperative outcomes. ⋯ PETSCSC scores and subscores demonstrate significant correlation with pain outcomes used in assessment of SCS efficacy. Higher PETSCSC scores correlate with greater improvement in GIC, MPQ affective, and PCS scores. Stratification of these patients based on PETSCSC total and subset scores could help with prognostication.
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Clinical high-frequency spinal cord stimulation (hfSCS) (>250 Hz) applied at subperception amplitudes reduces leg and low back pain. This study investigates, via labeling for c-fos-a marker of neural activation, whether 500 Hz hfSCS applied at amplitudes above and below the dorsal column (DC) compound action potential (CAP) threshold excites dorsal horn neurons. ⋯ The finding of enhanced c-fos expression in the ipsilateral superficial dorsal horn provides evidence for activation/modulation of neuronal circuitry associated with subperception hfSCS.