Intravenous lidocaine helps after fusion, not after decompression

Design

systematic review and random-effects meta-analysis with post-hoc subgroup analysis and meta-regression

Population

10 randomised trials of perioperative intravenous lidocaine in adult spine surgery; 655 patients for the primary outcome

Primary outcome

postoperative pain intensity at 24 hours

Effect

overall MD −0.83 (95% CI −1.36 to −0.30); fusion or complex surgery −1.23 (−1.81 to −0.64); decompression −0.20 (−0.61 to 0.21)

Previous meta-analyses of perioperative intravenous lidocaine in spine surgery pooled every procedure together. This one searched to June 2026, found 10 randomised trials, and asked whether the effect differs by what was actually done.

Overall, lidocaine reduced 24-hour pain (mean difference −0.83, 95% CI −1.36 to −0.30, 9 trials, 655 patients, moderate certainty) and opioid consumption by 11.64 mg intravenous morphine equivalents (−16.14 to −7.14). Heterogeneity was high at I² 89 per cent. In a post-hoc subgroup analysis the effect split cleanly: after instrumented fusion or complex spine surgery the reduction was −1.23 (−1.81 to −0.64), above the minimal clinically important difference of one point; after decompression alone it was −0.20 (−0.61 to 0.21). Baseline pain severity explained about 53 per cent of the heterogeneity between studies; infusion rate explained none of it. There was no effect on nausea and vomiting or length of stay.

The authors flag the subgroup finding as exploratory and hypothesis-generating, and it should be read that way. But the direction is mechanistically coherent — the benefit appears where baseline pain is high — and it argues for selecting lidocaine by expected pain rather than running it on every spine list.

• Reserve lidocaine infusion for instrumented fusion and complex spine procedures
• Do not expect meaningful analgesia from it after isolated decompression
• Select by expected baseline pain severity, which explained half the variation between trials
• Do not tune the infusion rate expecting a bigger effect — rate did not modify the result
• Do not use it for nausea or length of stay; neither moved

Why it matters

It replaces an all-lists protocol with a selection rule, and the selection rule is the part that changes drug use.

Don't overread it

The procedure-specific difference came from a post-hoc exploratory subgroup analysis and is hypothesis-generating.

The statistics, in plain English

An I² of 89 per cent means the trials disagree substantially, and the prediction interval (−2.69 to 1.02) crosses zero: a future trial could plausibly show no benefit. The overall −0.83 sits below the one-point threshold usually taken as clinically noticeable, which is why the subgroup split matters — the average is diluted by procedures where it does nothing.

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