Cryoneurolysis outcome on patient experience) - A randomized controlled blinded trial

STUDY DESIGN: Prospective randomized controlled blinded clinical study, commencing in 2019 to 2022
OBJECTIVE: The primary aim of the study is to investigate the effect of cryoneurolysis in a lumbar joint pain syndrome in a controlled state-of.-the art setting. The secondary aims are to compare the effect of cryoneurolysis to standard treatment for facet joint pain syndrome and to investigate whether pre-defined parameters are independent factors for outcome in the procedure.
BACKGROUND: Low back pain is estimated to be affecting 800.000 people in Denmark accounting for up to 20 percent of total sick leave. A review from 2007 found the level of evidence for the efficacy of denervation procedures for lumbar medial branch nerves either by radiofrequency or cryonecrolysis to be moderate for short and long-term pain relief. One prospective trial found a significant pain reduction at all follow-up times to one year which was the last follow-up. Current literature displaying the effect of cryonecrolysis on facet joint pain syndrome are sparse and all based on case series, the majority of which retrospective. The need for a randomized controlled trial to evaluate the true effect of cryoneurolysis is apparent.
METHODS: Recruitment of patients will commence from May 2019 to April 2021. The patients will be recruited from the common spine patient visitation at Aarhus University Hospital and Silkeborg Spine Center. Eligible patients will be referred to the outpatient clinic at the Department of Neurosurgery, Aarhus University hospital for further evaluation before enrolling in the study. Inclusion criteria: Age above 18, presence of low back pain without radiation into the leg for more than 3 months, absence of nerve root compression signs on MRI, absence of inflammatory or erosive processes in the spine verified on MRI, no neurological deficits. Exclusion criteria: major co-morbidity, anti-thrombotic treatment which cannot be paused for a week, malignancies, chronic inflammatory disease and known psychiatric disease. Further evaluation at the outpatient clinic consists of 1) anamnestic and neurological examination to pinpoint the most painful spine level 2) MRI or CT confirming degenerative or otherwise distinct facet joint 3) Diagnostic anesthetic block based on anatomical localization of the facet joint pain generator unilaterally. If there is more than 50% reduction in NRS Score within 3 hours, a second block will be scheduled. The procedure for the second block is the same however guided by fluoroscopy to target the intended medial branch of the dorsal rami. If NRS score is reduced by more than 50% within 3 hours, the patient is included in the randomization stage of the study. A total of 315 participants will randomized into 3 groups of 105 to undergo either 1) one treatment of cryoneurolysis (cryo) or 2) radiofrequency ablation or 3) the same procedure setup including needle insertion but with the apparatus turned off (placebo). Both groups will undergo rehabilitation physiotherapy instituted individually for the next 3 months. The randomization will be delivered in 315 numbered and sealed envelopes, only to be opened by the doctor performing the interventions in the OR.
The primary outcome measure is the Numeric Rating Scale (NRS-11). The secondary outcome measures are the Oswestry Disability Index, the EQ-5D and SF-36 instrument, the Patient Global Impression of Change (PGIC), the pain Catastrophizing Scale (PCS) and the Major Depression Inventory (MDI). All measures assessed the endpoint outcomes at baseline, follow-up at day 1 and 3, 6, 12 month after the first treatment. By 12 month follow-up a final MRI will be conducted for the safety evaluation of the procedure.
RESULTS: All forms will be electronic and collected in the Aarhus University REDCap database system, a secure web application for building and managing online surveys and databases of research data. For statistical analysis in regards to study paired samples, t-test will be used on the group of units (cryo or Placebo) that will be tested twice, before and after intervention to eliminate the random between-patient variation.
CONCLUSION: Low back pain in patients with facet joint syndrome can have a disabling effect on the individual and on society. The study aims to elucidate the fundamental information about cryoneurolysis as an alternative treatment option to those currently available to low back pain patient with facet join pain syndrome. The current literature displays that the effect of cryonecrolysis on facet joint pain syndrome is sparsely investigated and all based on case serie, the majority of which are retrospective. The need for a randomized controlled trial to evaluate the true effect of cryoneurolysis is apparent.