Related Experiment Video
Updated: Oct 9, 2026
Spinal Sonography for Ultrasound-Guided Lumbar Neuraxial Anesthesia
Published on: January 31, 2025
Prospective experience with a 20-gauge Tuohy needle for lumbar epidural steroid injections: Is confirmation with
S S Liu1, A P Melmed, J W Klos
1Department of Anesthesiology, Virginia Mason Medical Center, Seattle, Washington, USA. anessl@vmmc.org
Background And Objectives:
Small (20-gauge) Tuohy needles have been introduced for epidural steroid injection to optimize patient comfort and decrease the risk of spinal headache. These needles may be less reliable for indentification of the epidural space than standard 17- or 18-gauge needles because of their small size. We prospectively examined the success rate of lumbar epidural steroid placement with loss-of-resistance (LOR) technique compared with fluoroscopy confirmation.
Methods:
One hundred patients without history of lumbar spine surgery were enrolled. A 20-gauge Tuohy needle was placed into the epidural space using LOR to saline. Confidence in epidural placement was recorded (Yes/No). Radiologic contrast was then injected and a fluoroscopic epidurogram interpreted by a blinded radiologist for correct placement, (Yes/No) separate from the clinical process.
Results:
Reliability of LOR was less than our "gold standard" of fluoroscopy (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 placement of standard 17- or 18-gauge Tuohy needles, we observed a success rate of 92%. Small-gauge Tuohy needles are technically more difficult to use than larger needles and may require confirmation with fluoroscopy for correct epidural placement, especially in elderly male patients.