An Operator's Experience of the Loss-of-Resistance Technique in Epidural Injections: An Observational Study

A successful interlaminar epidural injection relies on correct epidural space needle placement. Most interlaminar epidural steroid injection (ESI) procedures are performed with a blind technique known as loss-of-resistance (LOR) without an imaging guide. This study aims to evaluate the success rate of the LOR technique in interlaminar epidural steroid injection under fluoroscopic control.

Patients who underwent interlaminar ESI owing to a history of at least 3 months of chronic low back and leg pain not responding to medications and physical therapies were included in an observational trial. Participants' age was between 27 and 88 years, and they had an American Society of Anesthesiologists physical status of I-III. The patients were placed in a prone position, and a Tuohy needle was introduced at the level of the L5-S1 interlaminar foramen using fluoroscopic image with an anteroposterior view. A lateral view was obtained when the LOR was felt. The procedures that achieved epidural spread by contrast agent in the first attempt were deemed successful. Those that did not and those that had false positive LOR were regarded as unsuccessful.

Interlaminar ESİ was administered to 150 patients. The procedure's success and failure rates were 76% (114 patients) and 24% (36 patients), respectively. A total of 58.3% (21 patients) of patients who underwent an unsuccessful procedure had a false LOR, whereas 41.6% (15 patients) of the same group exhibited other causes. Sex, age, and body mass index (BMI) showed no statistical significance in terms of procedural success. There were statistically significant differences in the distance between the skin and the epidural space according to the body mass index groups.

The LOR technique identified the epidural space in most epidural procedures. However, in some cases, LOR was shown to be inadequate. Therefore, we suggest that the LOR technique must be supported by imaging such as fluoroscopy during epidural injections.