Understanding Injections for Sciatica: What the Latest Evidence Says

Part of a series of Spine Tuesday Webinars.

Overview of Evidence Presented

Today we present three different sources of evidence:

•     A meta-analysis/Cochrane review of data on injections for sciatica
•     A randomised controlled trial comparing nerve root block vs surgery (NERVES trial)
•     A cohort study exploring predictors of improvement after injection therapy (POISE study)

1. Meta-analysis: Cochrane Review on Epidural Injections

Scope:

Examined the safety and efficacy of epidural corticosteroid injections for radicular pain (leg pain from nerve root irritation).

•     Included patients with symptoms <6 weeks, 6–12 weeks, and >12 weeks
•     Some patients without imaging or central stenosis were also included
•     Injection types: caudal, interlaminar, transforaminal
•     Control groups varied widely

Outcomes Measured:

    Pain levels and disability using the Oswestry and Roland-Morris scales

    Outcome timing:

•         Immediate (<2 weeks)
•         Short-term (2–12 weeks)
•         Intermediate (3–12 months)
•         Long-term (>12 months)

Findings:

•     Moderate evidence for short-term leg pain relief
•     Poor evidence for disability improvement at any timeframe
•     No clinically meaningful difference observed

Conclusion:
Evidence is weak and based on flawed data — difficult to draw solid conclusions.

2. The NERVES Trial: Surgery vs Nerve Root Block

Presented by Mr Martin Wilby – Consultant Neurosurgeon, The Walton Centre

Why Was This Trial Needed?

The Cochrane review included highly variable (heterogeneous) studies, making it difficult to trust the findings. A rigorous randomised controlled trial was needed.

Study Design

•     NIHR-funded multicentre RCT
•     Compared transforaminal nerve root block vs surgery
•     Included patients with symptoms 6 weeks to 1 year
•     Excluded cases with cauda equina syndrome or significant motor deficit
•     Included economic and clinical evaluations

Background Evidence

•     Weber (1980s): 70% improved in 4 weeks; 60% returned to work
•     Surgery vs Conservative: Surgery showed 90% good outcome, conservative 60%
•     SPORT study (2014): No difference at 12 months between usual care and surgery
•     Most other studies are observational and suggest many patients avoid surgery with conservative care

Results

•     Both groups improved significantly
•     No significant difference in outcomes (leg pain, back pain, disability) at 1 year
•     4 serious adverse events all occurred in the surgery group (including 1% neurological deficit)
•     Surgery cost ~£38,000 more per patient

Conclusion:
In non-emergency cases, transforaminal injections are as effective as surgery — with fewer risks and much lower costs.

3. The POISE Study: Predicting Who Benefits from Injections

Presented by Dr Siobhan Stynes – Specialist Physiotherapist & Research Fellow, Keele University

Study Design

•     Prospective cohort study in physiotherapy clinics
•     NIHR-funded
•     Follow-up at 6 weeks, 3 months, and 6 months after injection
•     Average duration of symptoms before injection: 9 months
•     58% consented; 2/3 completed 6-month follow-up
•     Most participants were working-age adults

Findings

•     60% reported improvement at 6 weeks
•     Overall less improvement than in the NERVES trial
•     Prognostic indicators (high certainty):
  •         Current level of leg pain
  •         Duration of symptoms
  •         Expectations of treatment benefit
  •         Opioid medication use
•     No reliable predictive model could be established
•     Delayed access to injections may contribute to poorer outcomes

Conclusion:
Earlier access to injection may improve outcomes. Patient expectations and symptom duration appear to influence benefit.

Key Takeaways

•  Injections can help relieve leg pain caused by sciatica, especially in the short term.
• For most people, injections and surgery provide similar symptom relief, but surgery carries higher risks and costs.
• Around 60% of patients feel better within 6 weeks after an injection.
• There’s no reliable way to predict exactly who will benefit, but shorter symptom duration and positive expectations tend to be associated with better outcomes.
• Earlier access to injections may improve effectiveness — delays could reduce benefit.
• For non-urgent cases, trying injections before considering surgery is safer and more cost-effective.

Written by Patient Line Committee Member Simon Clark.