Subjects with chronic pain that have been scheduled to receive spinal cord simulators for standard of care treatment.

Chronic Pain

Step 1: Recording and stimulation of spinal potentials during insertion of epidural spinal stimulator paddle
Once the epidural paddle is placed, study procedures will begin by connecting the terminals of the paddle to an electrophysiological recording device for signal amplification and filtering. Using this recording setup, motor evoked potential (MEP) and somatosensory evoked potential (SSEP) protocols will be performed to determine motor and sensory thresholds, respectively. Next, the surgical procedure will resume and after the implantable pulse generator (IPG) has been placed, study procedures will begin again and include activation of both low-frequency tonic stimulation (LFTS) and high-frequency burst stimulation (HFBS) patterns from the inserted paddle while recording EMG signals.

Intraoperative Parameter Testing

Step 3: Proprioception testing
The research team will investigate the perceived change in knee joint angle and direction of movement reported by the subject in a Threshold to Detect Passive Movement (TTDPM). The TTDPM protocol will begin with the subject sitting in the Biodex testing seat, with the non-tested leg hanging freely and the tested leg strapped to the rotating arm of the dynamometer at the lower shank. The subject will be blinded as to the mode and intensity of stimulation: HFBS, LFTS, or no stim. The TTDPM will consist of at least 10 trials for each stimulation condition chosen based on SCM outcomes. The subject has control of a kill-switch that immediately halts movement of the rotating arm, which is to be activated once the subject perceives movement OR if the subject begins to feel any pain or discomfort throughout the task.

Proprioception Testing During Stimulation

Step 4: Body weight support and treadmill (BWST) testing
Similar to step 2, LFTS and HFBS patterns will be compared by systematically testing each individual contact on the paddle while investigating for changes in stepping speed, pattern and EMG moduling complexity. Regarding EMG module analysis, muscle activity will be recorded bilaterally via surface EMG from lower extremity musculature. Furthermore, subjects will also have active LED markers placed over their clothes in order to track whole body kinematics throughout this portion of the study.
To optimize capture of steady state data on the treadmill, each subject will walk for approximately 10 sec prior to the 30 sec of data collection (40 sec per trial). This will allow capture of at least 10 consecutive steady state gait cycles (depending on cadence) per each amplitude selection for each stimulation delivery technique, which will be defined by parameters found during walking SCM.

Gait Analysis During Stimulation

Medical University of South Carolina

Effect of Epidural Stimulation on Muscle Activation and Sensory Perception

Neuromodulation of Motor and Sensory Spinal Pathways in Subjects Undergoing Epidural Spinal Cord Stimulation

During intraoperative testing of varying stimulation parameters, the research team plans to collect evoked potentials via electromyography (EMG) as the primary outcome for step one. Evoked potential amplitude, recorded at specific muscles of interest, will be collected for nerve root activation threshold. The research team plans to look at musculature receiving innervation from varying levels of the spinal cord in order to determine any difference among stimulation type regarding nerve root isolation.

Proprioception signaling will be tested using a Biodex machine that can apply passive flexion/extension at the knee while the subject reports 1) Feeling of movement and 2) Direction of movement. Specific data of interest will be the amount of degrees of flexion/extension of the knee that have occurred before the subject perceives the movement, which is reflective of proprioceptive signaling. Testing while experiencing varying types of stimulation will yield important information regarding physiological sensory modulation from the stimulator. The research team plans to use a repeated measures two-way ANOVA with epidural stimulation type and current amplitude of above and below EMG activation threshold to investigate effects on proprioception detection signaling.

During gait analysis, the research team plans to collect surface electromyography (EMG) signals of lower extremity musculature to measure activation synergies and amplitudes. Segments of EMG that are recorded during walking will be analyzed with an algorithm that yields hierarchal complexities representing muscle synergies known as EMG moduling. The research team plans to use a two-way repeated measures ANOVA model in order to investigate the varying differences in stimulation type and effect on EMG module complexity to investigate the relationship between sensory pathway modulation and motor control during functional task.

Potential participants will be informed during the consent process that information about them (including identifiable private information) may have all of their identifiers removed and used for future research studies or distributed to other researchers for future research without additional informed consent from them.

arteriovenous malformations/fatigue

Effect of Epidural Stimulation on Muscle Activation and Sensory Perception

La base de données d'herbes médicinales la plus complète soutenue par la science