Effect of addition of epidural ketamine to steroid in lumbar radiculitis: one-year follow-up.

BACKGROUND: Treating sciatica with epidural steroid injection has been a common practice worldwide. N-methyl-D-aspartate (NMDA) receptors are an important component of pain pathways.

OBJECTIVES: The aim of this study was to evaluate the safety and efficacy of epidurally administered NMDA receptor antagonists (ketamine) for the treatment of chronic low back pain secondary to radiculopathy and its effect on patients' quality of life.

STUDY DESIGN: Randomized, double blind controlled trial.

SETTING: Hospital outpatient setting.

METHODS: Two hundred participants aged 25 to 50 years old with a diagnosis of lumbar radiculopathic pain secondary to disc herniation were randomized into 2 equal groups. Group I received 80 mg of triamcinolone (2 mL) and 0.25% bupivacaine (3 mL) plus 30 mg (3 mL) of preservative free ketamine. Group II received 80 mg of triamcinolone (2 mL) and 0.25% bupivacaine (3 mL) plus 3 mL of 0.9% saline. Pain scores were obtained before injection, immediately after injection, one week, one month, 3 months, 6 months , 9 months and one year post injection. The Oswestry Low Back Pain Disability Questionnaire was used at baseline and at one month, 3, 6, 9, and 12 months after injection for assessment of quality of life. Patients were asked to report any side effects, particularly those related to ketamine, including nausea, vomiting, visual or auditory hallucinations, and delirium.

RESULTS: Immediately after injection there was no statistically significant difference between Group I and II regarding pain scale scores. After one week of injection, pain relief was significantly better in Group I compared to Group II and then at all evaluation times. The Oswestry Low Back Pain Disability Questionnaire score decreased significantly (P < 0.05) from 72 (range 62- 83) and 70 (range 57- 82) to 8 (range 2 - 12) and 17 (range 9 - 27) at one month; 6 (range 4 - 12) and 18 (range 14 - 22) at 3 months; 12 (range 9 - 16) and 28 (range 22 - 34) at 6 months; 17 (range 9 - 24) and 31 (range 21 - 35) at 9 months; and 17 (range 8 - 22) and 33 (range 20 - 37) at 12 months in the groups, respectively. Six patients in the ketamine group showed short-lasting delusions lasting for 45 ± 12 minutes after injection.

LIMITATIONS: The limitations include a lack of placebo control.

CONCLUSION: Epidurally administrated ketamine seems to be a safe and useful adjunct to epidural corticosteroid therapy in chronic lumbar radicular pain.