BackgroundHypertonic dextrose injection (prolotherapy) is reported to reduce pain including non-surgical chronic low back pain (CLBP), and subcutaneous injection of 5% dextrose is reported to reduce neurogenic pain, hyperalgesia and allodynia. The mechanism in both cases is unclear, though a direct effect of dextrose on neurogenic pain has been proposed. This study assessed the short-term analgesic effects of epidural 5% dextrose injection compared with saline for non-surgical CLBP.MethodsRandomized double-blind (injector, participant) controlled trial. Adults with moderate-to-severe non-surgical low back pain with radiation to gluteal or leg areas for at least 6 months received a single epidurogram-confirmed epidural injection of 10 mL of 5% dextrose or 0.9% saline using a published vertical caudal injection technique. The primary outcome was change in a numerical rating scale (NRS, 0 - 10 points) pain score between baseline and 15 minutes; and 2, 4, and 48 hours and 2 weeks post-injection. The secondary outcome was percentage of participants achieving 50% or more pain improvement at 4 hours.Results and ConclusionsNo baseline differences existed between groups; 35 participants (54 ± 10.7 years old; 11 female) with moderate-to-severe CLBP (6.7 ± 1.3 points) for 10.6 ± 10.5 years. Dextrose participants reported greater NRS pain score change at 15 minutes (4.4 ± 1.7 vs 2.4 ± 2.8 points; P = 0.015), 2 hours (4.6 ± 1.9 vs 1.8 ± 2.8 points; P = 0.001), 4 hours (4.6 ± 2.0 vs 1.4 ± 2.3 points; P < 0.001), and 48 hours (3.0 ± 2.3 vs 1.0 ± 2.1 points; P = 0.012), but not at 2 weeks (2.1 ± 2.9 vs 1.2 ± 2.4 points; P = 0.217). Eighty four percent (16/19) of dextrose recipients and 19% (3/16) of saline recipients reported ≥ 50% pain reduction at 4 hours (P < 0.001). These findings suggest a neurogenic effect of 5% dextrose on pain at the dorsal root level; waning pain control at 2 weeks suggests the need to assess the effect of serial dextrose epidural injections in a long-term study with robust outcome assessment.

Epidural D5W injection, in the absence of anesthetic, resulted in consistent postinjection analgesia and clinically significant improvement in pain and disability through 12 months for most participants. The consistent pattern postinjection analgesia suggests a potential sensorineural effect of dextrose on neurogenic pain.

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