Deep neuromuscular block cut 3-month chronic pain after lumbar fusion, but the gap narrowed by 6 months

Design

Randomised clinical trial, modified intention-to-treat

Population

178 adults having posterior lumbar interbody fusion

Primary outcome

Chronic postsurgical pain at 3 months

Effect

19.1% vs 34.8%; RR 0.6 (95% CI 0.3 to 0.9); at 6 months 14.6% vs 19.1%, RR 0.8 (0.4 to 1.5)

This randomised trial allocated 180 patients having posterior lumbar interbody fusion to deep or moderate neuromuscular block, with 178 analysed. The idea is that deeper relaxation reduces the force needed for paraspinal retraction, and so muscle damage.

Chronic postsurgical pain at three months, the primary outcome, occurred in 19.1% with deep block and 34.8% with moderate block (RR 0.6, 95% CI 0.3 to 0.9). At six months the difference was smaller and not significant (14.6% vs 19.1%). The deep block group also had lower pain scores and opioid use after surgery, lower creatine kinase, myoglobin and LDH on day one, better preserved paraspinal muscle on six-month MRI, and higher surgeon satisfaction.

Deep block needs quantitative monitoring and full reversal, and sugammadex is not always available or affordable in Indian theatres; neostigmine cannot reliably reverse deep block. Teams who can monitor and reverse it safely have a reasonable case for using it in open lumbar fusion, while recognising that the lasting effect on chronic pain is not yet established.

• Consider deep neuromuscular block for open posterior lumbar fusion where quantitative monitoring and reliable reversal are available.
• Use quantitative neuromuscular monitoring and confirm full recovery before extubation.
• Plan reversal before choosing deep block: neostigmine cannot reliably reverse it.
• Combine with multimodal analgesia; deep block was one part of reduced opioid use, not a substitute.
• Follow up spine patients for persistent pain at three months.

Why it matters

It suggests an anaesthetic choice can reduce surgical muscle injury and early chronic pain after spine surgery.

Don't overread it

The benefit was clear at three months but not significant at six; the trial was not powered to show a lasting effect.

The statistics, in plain English

A risk ratio of 0.6 means chronic pain at three months was about 40% less common with deep block. The interval (0.3 to 0.9) excludes no effect but is wide. At six months the interval (0.4 to 1.5) includes no effect.

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