Evaluation of Medication Tapering on the Sensitivity of the Spinal Cord Using Closed-Loop Spinal Cord Stimulation (Pilot Study) (ECAP-MED Pilot)

Neurophysiological Effects of Pain Medication Reduction During Treatment With Closed-Loop Spinal Cord Stimulation: A Pilot Study

This pilot study investigates the effects of reducing pain medication including opioids and anticonvulsants, on spinal cord sensitivity during closed-loop spinal cord stimulation (SCS). Patients with Persistent Spinal Pain Syndrome Type 2 (FBSS/FNSS) will undergo a standard 21-day SCS trial with the Evoke closed-loop system, followed by permanent implantation if successful. Neurophysiological responses (activation plots, conduction velocity, chronaxie, rheobase) and patient-reported outcomes (VAS, activity, sleep, medication intake) will be collected during the trial and up to 6 months after implantation. The goal is to evaluate the relationship between medication tapering and spinal cord sensitivity

Study Overview

• Status: Recruiting
• Conditions: Neurophysiological Sensitivity to Spinal Cord Stimulation; Failed Back Surgery Syndrome (FBSS); Persistent Spinal Pain Syndrome Type 2 (PSPS-T) Lower Spine
• Intervention / Treatment: Other: Spinal Cord Stimulation with Evoke Closed-Loop System

Detailed Description

This is a single-centre, open-label, prospective pilot study in Belgium. Twenty patients scheduled for SCS with the Evoke ECAP-controlled closed-loop system will be enrolled. Eligible patients must use at least one qualifying pain medication at a minimum daily dose (gabapentin ≥150 mg, pregabalin ≥75 mg, morphine ≥40 mg, hydromorphone ≥10 mg, oxycodone ≥20 mg, fentanyl ≥25 µg).

The study includes baseline assessments, a 3-week trial period, permanent implantation if successful, and follow-up visits at 1, 3, and 6 months. Data collected include VAS pain, sleep, activity, medication use, and neurophysiological parameters (activation plots, conduction velocity, chronaxie, rheobase).

The primary endpoint is the effect of medication reduction on spinal cord sensitivity to SCS. Secondary endpoints include changes in pain intensity, medication use, sleep, activity, and additional neurophysiological outcomes.

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

• Study Contact: Name: Pieter Van Looy; Phone Number: +32 3 443 48 72; Email: pieter.vanlooy@zas.be

Study Locations

• Belgium
  • Wilrijk, Belgium, 2610
    • Recruiting
    • Brai²n - ZAS Augustinus
    • Contact: Pieter Van Looy; Phone Number: +32 3 443 48 72; Email: pieter.vanlooy@zas.be
    • Principal Investigator: Tony Van Havenbergh, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Belgian patients selected for spinal cord stimulation (SCS) with Failed Back Surgery Syndrome ( FBSS )

Description

Inclusion Criteria:

• Candidate for SCS and scheduled for trial with Evoke system.
• Diagnosis of FBSS or FNSS (PSPS-T2).
• Current use of ≥1 qualifying pain medication at or above minimum daily dose:
• Gabapentin ≥150 mg
• Pregabalin ≥75 mg
• Morphine ≥40 mg
• Hydromorphone ≥10 mg
• Oxycodone ≥20 mg
• Fentanyl ≥25 µg
• Signed informed consent.
• Age ≥18 years.

Exclusion Criteria:

• Active disruptive psychiatric disorder or condition impacting pain perception or compliance.
• Progressive neurological disease (MS, CIDP, progressive arachnoiditis, progressive diabetic neuropathy, brain/spinal tumor, severe spinal stenosis).
• Coagulation disorder, platelet dysfunction, progressive vascular disease, or uncontrolled diabetes with procedural risk.
• Active systemic or local infection.
• Pregnancy.
• Significant untreated addiction or substance abuse (within 6 months prior)

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients with FBSS, taking at least qualifying opioids; Patients with FBSS, taking at least one qualifying pain medication at or above the minimum daily dose.	Other: Spinal Cord Stimulation with Evoke Closed-Loop System; All patients undergo a 21-day trial with Evoke closed-loop SCS. If successful, patients receive a permanent implant. Assessments include activation plots, conduction velocity, chronaxie, rheobase, VAS pain, sleep, activity, and medication intake.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	From start of SCS trial (baseline) to 6 month after permanent implantation.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	From start of SCS trial (baseline) to 6 month after permanent implantation.
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.	From start of SCS trial (baseline) to 6 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.	From start of SCS trial (baseline) to 6 month after permanent implantation.
Changes in sleep and activity scores	Participants will be required report their sleep and activity scores using a 10 cm visual analog scale (VAS) where 0 refers to no sleep and no activity at all and 10 refers to sleeping very well through the night and being very active. The resultant VAS score, expressed in cm, will be compared across study visits.	From start of SCS trial (baseline) to 6 month after permanent implantation

Collaborators and Investigators

• Sponsor: Brai²n
• Investigators: Principal Investigator: Tony Van Havenbergh, MD, PhD, Brai²n / Department of Neurosurgery, ZAS Augustinus, Antwerp, Belgium

Study record dates

Study Major Dates

• Study Start (Actual): June 8, 2022
• Primary Completion (Estimated): July 28, 2026
• Study Completion (Estimated): August 28, 2026

Study Registration Dates

• First Submitted: November 20, 2025
• First Submitted That Met QC Criteria: March 27, 2026
• First Posted (Actual): March 31, 2026

Study Record Updates

• Last Update Posted (Actual): March 31, 2026
• Last Update Submitted That Met QC Criteria: March 27, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Neuromodulation; opioids; Spinal cord stimulation; Neurophysiology; anticonvulsants; Closed-loop stimulation; Evoked Compound Action Potentials (ECAPs); Pain medication reduction
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Back Pain; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Failed Back Surgery Syndrome; Therapeutics; Physical Therapy Modalities; Rehabilitation; Electric Stimulation Therapy; Spinal Cord Stimulation
• Other Study ID Numbers: GZA-ECAP-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The international committee of medical journal editors believes there is an ethical obligtion to share data generated by interventional clinical trials. This is not considered an interventional clinical trial

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No