Spinal cord stimulation (SCS) is a common intervention for managing intractable pain. Generally, leads are implanted in a minimally invasive procedure with verbal feedback regarding the location and nature of generated paresthesias by active stimulation.

Since its introduction in the late 1960s ¹⁾ , epidural Electrostimulation of the dorsal columns of the spinal cord, commonly referred to as spinal cord stimulation (SCS), has been used frequently for the treatment of chronic pain.

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Spinal cord stimulation has emerged as a state of the art evidence based treatment for chronic neuropathic pain and mixed nociceptive-neuropathic pain. Several newer devices and treatment algorithms have provided unique and effective ways of treating chronic pain by spinal cord stimulation. In a previous review, Maheshwari et al., from University Hospitals Cleveland Medical Center, Evolve Restorative Center, Santa Rosa, The Spine and Nerve Centers of Virginia, Functional Neurosurgery St. Luke's University Hospital Bethlehem , commented on the five-year forecast for high frequency and Burst wave forms, as the only two paresthesia independent SCS strategies. Over the last five years there has been considerable addition to the outcome data related to these modalities. Additionally, new treatment algorithms and modalities for spinal cord stimulation have emerged.

In a new review, they provided an up to date summary of these modalities of treatment, indications and evidence on all different modalities and programming paradigms that are available today.

A literature review was performed using key bibliographic databases to find outcomes related studies pertaining to spinal cord stimulation, limited to the English language and human data, between 2010-18. The literature search yielded the following based on there inclusion criteria; six articles on burst stimulation, three articled on high density/high dose stimulation, six articles on Dorsal Root Ganglion stimulation, nine articles on high-frequency stimulation and one article on closed loop stimulation.

They also included in the discussion some smaller and anecdotal studies.

The evidence to support outcomes of spinal cord stimulation has evolved considerably since the last review in 2014. New targets, frequencies and pulse trains, and feedback appear to have advanced the efficacy of spinal cord stimulation. Future developments aim to continue to refine patient selection and maintenance of patients in therapy ²⁾.

Our traditional understanding of how spinal cord stimulation (SCS) works relies on gate control theory.

How spinal cord stimulation (SCS) in its different modes suppresses pain is poorly understood. Mechanisms of action may reside locally in the spinal cord, but also involve a larger network including subcortical and cortical brain structures. Tonic, burst, and high-frequency modes of SCS can, in principle, entrain distinct temporal activity patterns in this network, but finally have to yield specific effects on pain suppression. Here, we employ high-density electroencephalography (EEG) and recently developed spatial filtering techniques to reduce SCS artifacts and to enhance EEG signals specifically related to neuromodulation by SCS.

Materials and methods: We recorded high-density resting-state EEGs in patients suffering from pain of various etiologies under different modes of SCS. We established a pipeline for the robust spectral analysis of oscillatory brain activity during SCS, which includes spatial filtering for attenuation of pulse artifacts and enhancement of brain activity potentially modulated by SCS.

Results: In sensor regions responsive to SCS, neuromodulation strongly reduced activity in the theta and low alpha range (6-10 Hz) in all SCS modes. Results were consistent in all patients, and in accordance with the thalamocortical dysrhythmia hypothesis of pain. Only in the tonic mode showing paresthesia as side effect, SCS also consistently and strongly reduced high-gamma activity (>84 Hz).

Conclusions: EEG spectral analysis combined with spatial filtering allows for a spatially and temporally specific assessment of SCS-related, neuromodulatory EEG activity, and may help to disentangle therapeutic and side effects of SCS ³⁾.

High-frequency spinal cord stimulation

see Cervical spinal cord stimulation.

see Burst stimulation.

see Spinal cord stimulation indications.

see also Wireless spinal cord stimulation.

In order for SCS to be effective, it is necessary for the patient to feel the stimulation in the areas of pain.

Two techniques are used to place electrodes in the epidural space:

1. plate-like electrodes placed via hemilaminectomy

2. wire-like electrodes placed percutaneously with a Tuohy needle.

Following electrode placement, a trial with an external generator over several days determines if SCS is effective. The electrodes are removed unless clear improvement occurs, in which case an implantable pulse generator is placed subcutaneously.

Spinal cord stimulation outcome

PROSTIM study

Spinal cord stimulation case series

Stone LE, Falowski SM. Pre-Operative Imaging for Spinal Cord Stimulation: A Case Report of a Spinal Cord Tumor Identified by Screening Magnetic Resonance Imaging of the Thoracic Spine. Neuromodulation. 2018 Sep 13. doi: 10.1111/ner.12848. [Epub ahead of print] PubMed PMID: 30211964.