Burst Crossover Trial

Spinal Cord Burst Stimulation for Chronic Radicular Pain Following Lumbar Spine Surgery: A Randomized Double-blind Sham-controlled Crossover Trial

Spinal cord stimulation (SCS) is a widely applied therapy to treat chronic neuropathic pain, and one of the most common indications is persisting radicular neuropathic pain following lumbar spine surgery. In traditional SCS therapies, the objective has been to replace the pain sensation with paresthesia. The anticipation is that the electrical current alters pain processing by masking the sensation of pain with a comfortable tingling or paresthesia. Although patients mostly cope with paresthesia, a significant proportion reports that the sensation is unpleasant. 'Burst' SCS utilizes complex programming to deliver high-frequency stimuli. This SCS technique seems to provide paresthesia-free stimulation, resulting in better pain relief of low back and leg pain then traditional tonic stimulation. The widespread use of SCS has not been backed by solid evidence. The absence of placebo-controlled trials has long been an important point of criticism, but due to the nature of the intervention with sensation of paresthesia, studies with placebo control have so far not been considered possible. When 'burst' SCS is used the stimulation is often unnoticed by the patient, allowing comparison with placebo stimulation. The aim of this randomized double-blind sham-controlled crossover trial is to evaluate the efficacy of 'burst' spinal cord stimulation for chronic radicular pain following spine surgery.

During the 12 months following implantation of a spinal cord stimulation (SCS) system, the patients will undergo four three-month long periods with either burst SCS or no stimulation (sham) in a randomized order. All patients will undergo two periods of SCS and sham stimulation.

Burst stimulation utilizes complex programming to deliver high-frequency stimuli of a 40 Hz burst mode with 5 spikes at 500 Hz per spike delivered in a constant current mode

a subcutaneously implantable pulse generator ("pacemaker") for long-term therapy. The following system from Abbott will be implanted: ProclaimTM XR implantable pulse generator and Octrode® 8-contact lead

measured with version 2.0 of the Oswestry disability index (ODI) that has been translated into Norwegian and tested for psychometric properties. The ODI questionnaire quantifies disability for degenerative conditions of the lumbar spine and covers intensity of pain, ability to lift, ability to care for oneself, ability to walk, ability to sit, sexual function, ability to stand, social life, sleep quality, and ability to travel. The index is scored from 0 to 100. Zero means no disability and 100 reflects maximum disability.

measured by use of a body-worn accelerometer (activPALs from PAL Technologies Ltd., Glasgow, United Kingdom) attached by a waterproof tape to the midpoint of the patients' anterior right thigh

Inclusion Criteria: Have undergone ≥1 back surgeries and developed chronic radicular pain that has remained refractory to non-surgical treatment for ≥6 months Minimum pain intensity of 5/10 on the leg pain NRS at baseline Successful two-week SCS testing period with tonic stimulation (≥2 points reduction in leg pain NRS from baseline). This means patients will experience paresthesia during the SCS trial period Mandatory assessment at the Multidisciplinary outpatient clinic for back-, neck- and shoulder rehabilitation, St. Olavs University Hospital Exclusion Criteria: Coexisting conditions that would increase procedural risk (e.g., sepsis, coagulopathy) History of laminectomy or posterior fusion at the thoracolumbar junction, where percutaneous electrode end tips are routinely placed. Abnormal pain behavior and/or unresolved psychiatric illness. Unresolved issues of secondary gain or inappropriate medication use.