To compare the analgesic efficacy of two different doses of epidural ketamine in chronic low back-pain patients: A randomised double-blind study.

BACKGROUND AND AIMS

Ketamine, an adjunct to epidural steroid injections (ESI) for chronic back-pain provides better quality and prolonged duration of analgesia. The present study aims to evaluate the analgesic efficacy in terms of pain scores, duration of pain-free period, patient satisfaction score (PSS) and number of repeat injections with 25 mg versus 50 mg ketamine as adjuvants to ESI.

METHODS

In a prospective, randomised, double-blind trial at a tertiary care hospital, 60 patients of chronic low back-pain of either sex, aged 18-65 years, received preservative free 25 mg ketamine in Group I and 50 mg ketamine in Group II as adjunct to 40 mg triamcinolone in total 6 ml volume given epidurally. Baseline data along with follow-ups at 2, 4, 8 and 12 weeks post-procedure included assessment of pain using Visual Analogue Scale (VAS), duration, number of repeat blocks using PSS, Quality of Life (QoL) and side-effects. Categorical data analysed using the Chi-Square test, and continuous data using paired -test.

RESULTS

Pain evaluation within the groups over time showed significant improvement from baseline ( = 0.000), and between the groups showed comparable VAS scores at 12 weeks ( = 0.392). The PSS, pain-free duration and number of repeat injections were also statistically comparable. However, the QoL improved more in Group II vs Group I ( = 0.024). The short-lasting side effects were more in Group II, but no features of neurotoxicity were observed in any patient.

CONCLUSION

The analgesic efficacy of adjuvant therapy with 50 mg ketamine appeared comparable to 25 mg ketamine. Although, there was a better quality of life and longer pain-free interval with 50 mg ketamine, the side effects were more.