Spinal Cord Stimulation for Refractory Pain Randomized Controlled Trial: the PAcStim RCT

NCT07468591 | Not Yet Recruiting

• 1 other identifier: 4971
• Study Type: interventional
• Target: 90
• Locations: 0 countries
• Sites: N/A

Brief Summary

Neuropathic pain affects 6-10% of the global population and is poorly managed - current drug treatments succeed in only \~25% of patients. Spinal cord stimulation (SCS) modulates pain by electrically stimulating spinal dorsal column fibres. The newer paresthesia-free mode (PF-SCS, 500-10,000 Hz) appears more effective and tolerable than traditional paresthesia-based SCS, with superior outcomes shown in the SENZA-RCT. All promising PF-SCS studies have been unblinded, making them susceptible to placebo effects. The one blinded RCT that exists had significant methodological flaws (no washout period, single baseline measurement) that biased results toward the null. A blinded, multi-centre, crossover RCT in 90 patients comparing 6 weeks of active PF-SCS vs. 6 weeks of placebo stimulation, with a 2-week washout in between - designed to correct the flaws of the prior trial and definitively establish whether PF-SCS works beyond placebo.

Conditions

Chronic Pain Syndrome

Outcome Measures

Primary Outcomes (1)

• Evaluate the analgesic outcomes from PF-SCS against outcomes from placebo

  PAcStim will compare the effect of 6 weeks of treatment with PF-SCS and placebo on Pain intensity, measured using the 0 to 10 pain numeric rating scale

  14-week

Secondary Outcomes (1)

• Evaluate the impact of PF-SCS on daily activity and sleep duration

  14-week

Study Arms (2)

paresthesia-free spinal cord stimulation (PF-SCS)

EXPERIMENTAL

At the beginning of the PF-SCS phase, the unblinded trial nurse will set the stimulator to provide active stimulation \[500-1200 Hz at 70% of the perception amplitude - usually between 3 to 5 mA\], which will remain constant for the 6-week duration of this period.

Device: Paresthesia-free spinal cord stimulation

Placebo

PLACEBO COMPARATOR

At the beginning of the placebo phase, a trial nurse will set the stimulator to provide low-amplitude stimulation \[500-1200 Hz at 0.1 mA, an amplitude that does not confer analgesic effects\], which will remain constant for the 6-week duration of this period. Low-amplitude stimulation was selected as placebo to maintain participant blinding because this will mimic settings of PF-SCS on the display on the patient controller, and because it is a more acceptable control condition than no stimulation.

Device: Paresthesia-free spinal cord stimulation

Interventions

Paresthesia-free spinal cord stimulation DEVICE

At the beginning of the PF-SCS phase, the unblinded trial nurse will set the stimulator to provide active stimulation \[500-1200 Hz at 70% of the perception amplitude - usually between 3 to 5 mA\], which will remain constant for the 6-week duration of this period.

Placebo; paresthesia-free spinal cord stimulation (PF-SCS)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18 years or older
• Severe NP in the axial locations (neck and back) and/ or the limbs
• Undergoing an SCS implantation with a PF device

You may not qualify if:

• Previously implanted with an SCS device
• Not fluent in English
• Unable to provide written informed consent

Sponsors & Collaborators

• University Health Network, Toronto: lead

Study Officials

• Anuj A Bhatia, MD, PhD

  University Health Network, Toronto

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Emad Al Azazi, MD, PhD

CONTACT

4166035800; emad.al-azazi@uhn.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: All involved in the study (participants, study staff, outcome assessors, data analysts, investigators) will be blinded to the patient's treatment allocation. The SCS display will show identical information regardless of treatment type. Both treatments involve active stimulation to help with blinding. For example, both treatments draw power from the SCS and will require the device to be charged. As SCS in this study is paresthesia-freee, the treatments will be perceived as the same by the participants. To ensure blinding success, patients will guess their group at the end of the study to assess adequacy of blinding.
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Model Details: This study will follow a multi-center prospective double-blinded, two-arm placebo-controlled, equally randomized (1:1) cross-over comparative trial.

Study Record Dates

• First Submitted: February 26, 2026
• First Posted: March 12, 2026
• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: June 8, 2026

Record last verified: 2026-06