Prospective experience with a 20-gauge Tuohy needle for lumbar epidural steroid injections: Is confirmation with fluoroscopy necessary?

Background and Objectives: Small (20-gauge) Tuohy needles have been introdu ced for epidural steroid injection to optimize patient comfort and decrease the risk of spinal headache. These needles may be less reliable for indent ification of the epidural space than standard 17- or Is-gauge needles becau se of their small size. We prospectively examined the success rate of lumba r epidural steroid placement with loss-of-resistance (LOR) technique compar ed with fluoroscopy confirmation. Methods: One hundred patients without history of lumbar spine surgery were enrolled. ii 20-gauge Tuohy needle was placed into the epidural space using LOR to saline. Confidence in epidural placement was recorded (Yes/No). Rad iologic contrast was then injected and a fluoroscopic epidurogram interpret ed by a blinded radiologist for correct placement, (Yes/No) separate from t he clinical process. Results: Reliability of LOR was less than our "gold standard" of fluoroscop y (P < .004). Sensitivity of LOR was 99% and specificity was 27%. Positive and negative predictive values were 92% and 75%. Increased patient age (>70 years) and male sex were associated with poor reliability of LOR (P < .05) . Conclusions: In contrast to the reported 99% success rates for epidural pla cement of standard 17- or 18-gauge Tuohy needles, we observed a success rat e of 92%. Small-gauge Tuohy needles are technically more difficult to use t han larger needles and may require confirmation with fluoroscopy for correc t epidural placement, especially in elderly male patients.