Subcutaneous Stimulation as Add on Therapy to SCS toTreat Low Back Pain in FBSS
Condition: Low Back Pain; Failed Back Surgery Syndrome; Neuropathic Pain
MeSH terms: Neuralgia; Syndrome; Back Pain; Low Back Pain; Failed Back Surgery Syndrome
Study type: Interventional

Summary: 
      Aim of the study Failed back surgery syndrome (FBSS) is a clinical entity consisting of
      chronic leg and /or back pain due to radicular nerve damage. The effectiveness of Spinal Cord
      Stimulation (SCS) in the pain management of patients with FBSS is proven. Patients mostly
      have dominant leg pain, however a significant percentage of FBSS patients has a more
      pronounced back pain and are commonly excluded from SCS as it is often inadequate in
      relieving both the back and leg pain components. Recently some reports showed the benefit of
      subcutaneous stimulation (SubQ) for low back pain in patients with FBSS. This has been
      confirmed by a feasibility study performed by our group. The aim of the randomized controlled
      study is to evaluate the effect of SubQ on low back pain in FBSS patients for whom SCS gives
      an inadequate back pain relief.

      Hypothesis We hypothesize that SubQ in addition to SCS in FBSS patients with leg and low back
      pain is more effective in treating low back pain (i.e. >50% pain reduction) than SCS alone.
    

Detailed description: 
      Aim of the study FBSS is a clinical entity consisting of chronic leg and /or back pain due to
      radicular nerve damage. The effectiveness of SCS in the pain management of patients with FBSS
      is proven. Patients mostly have dominant leg pain, however a significant percentage of FBSS
      patients has a more pronounced back pain and are commonly excluded from SCS as it is often
      inadequate in relieving both the back and leg pain components. Recently some reports showed
      the benefit of subcutaneous stimulation (SubQ) for low back pain in patients with FBSS. This
      has been confirmed by a feasibility study performed by our group. The aim of the randomized
      controlled study is to evaluate the effect of SubQ on low back pain in FBSS patients for whom
      SCS gives an inadequate back pain relief.

      Hypothesis We hypothesize that SubQ in addition to SCS in FBSS patients with leg and low back
      pain is more effective in treating low back pain (i.e. >50% pain reduction) than SCS alone.

      Study design and duration of the study The study is a randomized controlled trial. Patients
      with FBSS with additional chronic back pain and an intensity of 5 or more for leg and back
      pain separately on the visual analogue scale are eligible for the study. About ninety
      patients will receive a SCS system targeting to relief leg and back pain. The study group
      consists of patients having a pain reduction of ≥50% in the leg after SCS trial stimulation.
      If, after trial stimulation, there is less than 50% back pain relief compared with initial
      values, patients will receive one or two Quad leads subcutaneously at the time of
      implantation of the pulse generator.

      This group, a total of 56 patients,will be randomized in a 1:1 ratio in which group 1 (n=28)
      receives SCS plus non-activated SubQ(SubQ OFF) and group 2 (n=28) receives SCS plus activated
      SubQ (SubQ ON) (phase 1), for a period of 3 months.

      After the controlled phase of the study, all 56 patients will receive maximal effective SCS
      and SubQ for the rest of the study duration (phase 2).

      Total duration of the study for a patient is12 months. Estimated duration of the study is 18
      months.

      Comparisons will be made after 3 months between no SubQ OFF and SubQ ON. After 6 and 12
      months (phase 2) patients will be compared with their baseline values to explore long term
      effects of SCS and SubQ.

      Type and number of patients The study will include FBSS patients with leg and low back pain,
      failing to relief back pain with SCS. For the controlled part of the study 56 patients are
      needed based on a power calculation in which a difference between the two treatments is
      postulated of about 40%. To assure this about 90 patients will be included in the study.

      Inclusion criteria Male/female > 18 and < 75 years Chronic neuropathic pain secondary to FBSS
      Pain radiating in lumbar segments L4 and/or L5 and/or S1 for at least 6 months Pain intensity
      assessed by VAS ≥ 5 scored separately for leg and back Willing to provide informed consent
      Exclusion criteria Presence of any other clinically significant or disabling chronic pain
      condition Expected inability of patients to properly operate the neurostimulation system
      History of coagulation disorders, lupus erythematosus, diabetes mellitus, rheumatoid
      arthritis or morbus Bechterew Active malignancy Current use of medicines affecting
      coagulation which cannot be temporarily stopped Evidence of an active disruptive psychiatric
      disorder or other known condition significant enough to impact the perception of pain,
      compliance to intervention and/or ability to evaluate treatment outcome as determined by the
      investigator Life expectancy of less than 1 year Existing or planned pregnancy Study therapy
      test therapy: Adequate subcutaneous stimulation with perceived paresthesias in the painful
      area in the back reference therapy: SCS plus non-activated SubQ (SubQ OFF) Parameters for
      evaluation of effectiveness primary outcome: The proportion of patients with SCS plus
      activated SubQ and SCS without activated SubQ having 50% or more pain relief(responder rate)
      in back after 3 months of stimulation, assessed with the VAS.

      secondary outcomes:

      Effect of SCS plus activated SubQ and SCS without activated SubQ after 3, 6 and 12 months on:

      Mean reduction in pain intensity for leg and back pain separately, assessed by the VAS
      Responder rate of SCS on leg pain assessed by the VAS Responder rate of SubQ on back pain
      assessed by the VAS(after 6 and 12 months) Quality of life assessed by Short Form 36 (SF-36)
      Quality of life as assessed by EuroQuol (EQ-5D) Function assessed by the Oswestry disability
      index Patient satisfaction assessed by the Global Impression of Change (GPIC) Pain assessed
      by the McGill questionnaire Concomitant drug treatment for relief of pain Concomitant need
      for physical therapy or other non-drug treatment. Employment status Frequency and nature of
      adverse events

      And in addition after 12 months of stimulation, on:

      Cost-utility Preferred stimulation settings
    

Intervention name(s): SubQ
Intervention type(s): Device
Intervention description(s): Spinal Cord Stimulation (SCS) and subcutaneous (SubQ) stimulation SCS trial stimulation: Implantation of the Octad lead in the epidural space. The lead implantation in the epidural space is performed under local anesthesia using a standard percutaneous technique. A key element to the technical success of an SCS procedure is the accurate placement of the lead, which results in paresthesia covering the patients' painful areas. This depends on the patients' feedback during intra-operative testing. Therefore, it is important that the patient is awake and fully cooperative during the trial stimulation.
Other intervention name(s): The octad lead (3877)SubQ leads (3888); (Prime Advanced 37702 or Restore Advanced 37713); all Medtronic
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: low back pain; failed back surgery syndrome; spinal cord stimulation; subcutaneous stimulation; peripheral nerve field stimulation