Introduction: Epidural steroid injection is commonly used for treatment of sciatica. Traditionally these have been administered through a needle inserted in the posterior mid line via an interlaminar (IL) route. However, in recent years the transforaminal (TF) route of administration has become popular. Potential advantages of the TF route include greater accuracy of injection (with radiological confirmation) and placement of the needle tip closer to the point at which the nerve is compressed.

Methods: Consecutive patients from the practices of 2 surgeons that use an IL technique were compared with those from the practices of 2 other surgeons that use a TF technique. Inclusion criteria were leg pain accompanied by a radiological diagnosis of nerve root compression. Both patients with disc prolapse and spinal stenosis were included. Treatment outcome was measured using the Roland-Morris (RM) Score, the Sciatica Frequency and Bothersome Index (SFBI) and the Euroqol (EQ-5D) questionnaire obtained at recruitment and three months after the epidural steroid injection. A global assessment (GA) of outcome; where patients were asked whether they were

much better,

Patients were also asked the duration of any relief obtained. Statistical methods utilized included the two tailed t-test, the Wilcoxon Rank Sum test, Odds ratio (OR) and the Chi Squared Test.

Results: 39 patients received an interlaminar epidural steroid injection and 25 received a transforaminal epidural steroid injection (total 64 patients). Follow-up was achieved for 36/39 (92.3%) and 25 (100%) patients respectively. The median pre-test RM score was 11 (range 3–11) for both groups. Post test RM score was 12(6–16) for the IL group and 3 (6–10.5) for the TF group (p=0.01). Median pre-test SFBI was 25 (0–46) and 26 (4–46) for the IL and TF groups respectively. Post test SFBI was 22 (0–46) and 18 (0–41) for the IL and TF groups respectively (p=0.003). Median pre- test EQ-5D was 0.54 for both groups (range 0.06–0.72 for the IL group and 0.08–0.72 for the TF group). Post test EQ-5D was 0.55 (0.06–1) for the IL group and 0.66 (0.06–1) (p=0.21). According to their GA, 11.1% felt much better, 33.3% felt better and 55.6% felt unchanged at 3 months in the IL group. 64% felt much better, 34% better and 12% felt unchanged in the transforaminal group. The proportion of patients having relief for 3 months or more after the injections was 3/36 (8.3%) for the IL group and 10/25 (40%) for the TF group. The transforaminal injection was 7 times more likely to result in pain relief at 3 months. (OR 7.3 95% CI 1.5 – 45.8, p=0.003).

Discussion: Epidural steroid injection by the transforaminal route is more effective then by the interlaminar route in the short term relief of sciatica.