Short Term Analgesic Effects of 5% Dextrose Epidural Injections for Chronic Low Back Pain: A Randomized Controlled Trial

BACKGROUND: Hypertonic 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. METHODS: Randomized 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 CONCLUSIONS: No 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.