This study is being conducted in patients who will receive a spinal cord stimulator. This device helps manage chronic neuropathic pain in the trunk and/or limbs. The patients will receive a spinal cord stimulator that is available, notified, and reimbursed in Belgium, which uses a special technology automatically adjusting the intensity of the stimulation. This is called a closed-loop system.
The closed-loop system stimulates the Beta fibers in the spinal cord and simultaneously measures their response. Based on the measured response, the stimulation strength is automatically adjusted. In Belgium, after implant of the leads the effect must first be evalauted for 3 weeks before implanting the Internal Pulse Generator; this is called the trial period. Only if the trial is successful, the patients will receive a permanent implant.
The primary goal of the study is to evaluate how different types of pain medication influence the neurophysiological response of the Beta fibers during spinal cord stimulation. Patients will be divided into three groups, based on the medication they are taking before receiving a spinal cord stimulator:
* patients not taking any pain medication, * patients taking strong opioids, * patients taking anticonvulsant medication.
As part of the study, patients will follow the normal clinical schedule. During visits, they will be asked questions about their pain, sleep, medication use, and activity. The study will end one month after the patient receives the permanent spinal cord stimulator implant.
Patient deemed a suitable candidate for SCS and routinely scheduled to undergo a trial phase with the Evoke SCS system.
Diagnosis of Persistent Spinal Pain Syndrome Type 2 (lower spine).
No strong opioids or anticonvulsants, or other analgesics
Monotherapy with a strong opioid, or
Evidence of an active disruptive psychological or psychiatric disorder, or other condition significant enough to impact pain perception, compliance with intervention, or ability to evaluate outcomes (as determined by the investigator in consultation with a clinical psychologist).
Current diagnosis of a progressive neurological disease such as multiple sclerosis, chronic inflammatory demyelinating polyneuropathy, rapidly progressive arachnoiditis, rapidly progressive diabetic peripheral neuropathy, brain or spinal cord tumor, or severe/critical spinal stenosis.
Current diagnosis or condition such as coagulation disorder, bleeding diathesis, platelet dysfunction, progressive peripheral vascular disease, or uncontrolled diabetes mellitus that presents excess risk for the procedure (as determined by the investigator).
Active systemic or local infection.
Belgian patients selected for spinal cord stimulation (SCS) with Persistent Spinal Pain Syndrome Type 2 (lower spine).
Cohort
Prospective
Spinal Cord Stimulation with Evoke Closed-Loop System
Other interventionAll participants will undergo trial stimulation with the Evoke ECAP-controlled closed-loop spinal cord stimulation system, followed by permanent implantation if the trial phase is successful. Neurophysiological parameters (activation plots, conduction velocity, chronaxie, rheobase) will be assessed alongside patient-reported outcomes (pain intensity, sleep, activity, medication use).
Spinal cord sensitivity expressed in ECAP amplitude (µV) as a function of the SCS stimulation amplitude (mA).
Spinal cord sensitivity to spinal cord stimulation (SCS), will be assessed using activation plots describing the relationship between SCS stimulation current (mA) and the resultant Evoked Compound Action Potential (ECAP) amplitude (µV). Change is spinal cord sensitivity (µV/mA) will be compared between the SCS trial phase and at 1 month after permanent implantation across the different medication groups.
Change in pain intensity measured using a 10 cm Visual Analog Scale (VAS)
Participants will be required report their pain intensity using a 10 cm visual analog scale (VAS) where 0 refers to no pain at all and 10 refers to worst possible pain. The resultant VAS score, expressed in cm, will be compared across study visits.
Change in pain medication intake measured via Belgian Pain Platform (BPP) and clinical verification
Reduction in analgesic medication dose (standardized daily dose or milligram equivalents, if applicable) will be documented using daily/weekly BPP entries and verified by clinical staff. Data will be compared between baseline, end of SCS trial, and 1 month after permanent implantation.
Change in neurophysiological parameters such as conduction velocity (m/sec), rheobase (mA) and chronaxie (µs), measured using the Evoke system's neurophysiological assessment tools.
The following neurophysiological parameters will be measured using the Evoke system's neurophysiological assessment tools. * Conduction velocity (meter/sec): Changes in SCS neural conduction velocity (m/sec) will be compared across baseline, during the SCS trial phase, and 1 month after permanent implantation. * Rheobase (mA): This is the lowest electrical current amplitude (mA) that can stimulate a nerve or muscle. Changes in rheobase will be compared across baseline, during the SCS trial phase, and 1 month after permanent implantation. * Chronaxie (µs): The minimum pulse duration (µs) needed to excite a nerve or muscle when the current strength is set to double the rheobase. Changes in chronaxie will be compared across baseline, during the SCS trial phase, and 1 month after permanent implantation.
