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Randomized Double-Blind Placebo-Controlled Trial of Selective Nerve Root Blockade (SNRB) in Acute Lumbar Disc Herniation and Sciatica
RS2001/02-026
Final Report Date: November 2006
| Principal Investigators: | Maziar Badii (Arthritis Research Centre of Canada), Paul Bishop (Vancouver Hospital) |
| Co-investigators: | Jacek Kopec (Arthritis Research Centre of Canada), Matthew Liang (Harvard Medical School) |
For more information about this project, please contact Dr. Maziar Badii.
Issue
Sciatica, a form of back-related pain that radiates down the leg, has been shown to benefit from a procedure called transforminal selective nerve root blockade (SNRB), which allows a precise and concentrated injection of medication into the affected area. However, past studies of SNRB have focused on post-acute sciatica, and it is not known whether SNRB has similar benefits during the acute stage. To address this knowledge gap, a clinical trial was conducted on SNRB treatment of sciatica in the acute stage (0-18 weeks).
Key findings
- Results varied depending on how long patients had been experiencing sciatica symptoms. The SNRB treatment resulted in better outcomes than the placebo when given to patients at 0-6 weeks of symptom duration, but worse outcomes than the placebo when given to patients at 12-18 weeks.
- Patients treated with SNRB were less likely to have surgery in the first year after treatment than patients receiving the placebo, but the difference was not statistically significant.
- The results support the use of SNRB for sciatica patients at 0-6 weeks, but not at 12-18 weeks.
Objectives
- To assess how SNRB treatment of acute sciatica affects patient outcomes including leg pain, back pain, functional ability and post-treatment surgery rates
Method
The study was a prospective double-blind randomized placebo-controlled trial. A total of 71 participants were recruited through a rheumatologist’s office, a neurosurgeon’s office, and the Vancouver General Hospital outpatient spine clinic. Participants were randomly assigned to the treatment group, which received SNRB with local anesthetic and corticosteroids or the control group, which received the placebo (injection with local anesthetic and normal saline).
Leg pain, back pain, and functional ability were assessed before treatment and at one hour, six weeks, six months, and one year post-treatment. Statistical analyses were conducted to compare outcomes for the treatment and control groups. Results were also analysed for three subsets of patients based on symptom duration at the time of treatment (0-6, 6-12, and 12-18 weeks).
Results
There were no statistically significant differences when the treatment group as a whole was compared with the control group as a whole. However, there were statistically significant differences for some outcomes when the treatment and control groups were compared for patients with specific symptom durations.
For patients treated at 0-6 weeks, SNRB was associated with better outcomes than the placebo. When treatment was given at 6-12 weeks, SNRB was associated with better outcomes only for back pain. When treatment was given at 12-18 weeks, SNRB was associated with worse outcomes than the placebo.
Patients treated with SNRB were 1.83 times less likely to have surgery in the year after treatment than patients who received the placebo. However, this result was not statistically significant.
Conclusions
The results of this study support the use of SNRB with corticosteroid for patients with sciatica in the first 6 weeks of symptoms, but not at 12-18 weeks after the onset of symptoms. It is not clear whether SNRB is beneficial at 6-12 weeks of symptom duration. A possible explanation for the findings is the role SNRB plays in reducing inflammation, which may help prevent nerve root injury in the first six weeks of symptoms but actually interfere with the healing process at 12-18 weeks.
Future directions
The researchers identified the need for further research in four key areas:
- To explain why SNRB is associated with better outcomes at 0-6 weeks but worse outcomes at 12-18 weeks
- To assess the effects of SNRB after 18 weeks of symptom duration
- To evaluate potential differences in post-treatment surgery rates in a larger trial (this study found that patients receiving the placebo were more likely to proceed to surgery than those treated with SNRB, but the result was not statistically significant)
- To assess whether SNRB treatment of acute sciatica can reduce sick time and improve return to work rates