Background: Epidural block failures can occur due to a misleading loss of resistance (LOR)
signal.
Objective: This study was designed to evaluate the false LOR rate and to determine whether
the Epidrum, which is an LOR device for identifying the epidural space, improves the ability to
find the epidural space during cervical epidural injection compared the LOR technique.
Study Design: A randomized, single-blind trial.
Setting: Single academic medical center.
Methods: A total of 150 patients undergoing cervical interlaminar epidural injections at
C7-T1 were randomized to receive either the LOR technique with a syringe (group C) or the
Epidrum guidance (group E). Fluoroscopic images were used to confirm the accuracy of the
needle placement within the epidural space. The rate of misleading epidural signals and
adverse effects were recorded and analyzed.
Results: The false LOR rate was 74.7% for group C, 62.7% for group E, and 68.7% overall.
The incidence of false LOR was not significantly different between the 2 groups. Also, the
success rate and the rate of true epidural signals were similar between the 2 groups.
Limitations: The Epidrum cannot be used to confirm whether the needle has entered the
vascular space without fluoroscopy.
Conclusions: In this study, we did not find any difference in accuracy between the Epidrum
and the LOR technique with a syringe for detecting the cervical epidural space. The overall
higher false LOR rate suggests that the combined use of fluoroscopy and LOR technique with
a syringe or the Epidrum is necessary to increase the rate of finding the true cervical epidural
space.
Clinical Trials registration: KCT0001333
Key words: Cervical epidural injection, epidural space, Epidrum, false positive, false negative,
loss of resistance
False Loss of Resistance in Cervical Epidural
Injection: The Loss of Resistance Technique
Compared with the Epidrum Guidance in
Locating Epidural Space
