Study design: A prospective, observational, human, in vivo study.
Objectives: To evaluate the incidence of vascular penetration during fluoroscopically guided, contrast-enhanced, transforaminal lumbar epidural steroid injections (ESIs) and determine whether a "flash" (blood in the needle hub) or aspiration of blood can be used to predict a vascular injection.
Summary of background data: Incorrectly placed, intravascular lumbosacral spinal injections result in systemic medication flow that misses the desired target. No previous studies evaluate the incidence of vascular injections in transforaminal ESIs, nor the ability of flash to predict a vascular injection.
Methods: The incidence of flash or positive blood aspiration and the incidence of fluoroscopically confirmed vascular spread were prospectively observed in 670 patients treated with lumbosacral fluoroscopically guided transforaminal ESIs. Presence of a flash or positive aspiration was documented. Contrast was injected to determine whether the needle tip was intravascular.
Results: Seven hundred sixty-one transforaminal ESIs were included. The overall rate of intravascular injections was 11.2%. There was a statistically significant higher rate of intravascular injections (21.3%) noted with transforaminal ESIs performed at S1 (n = 178), compared with those at the lumbar levels (8.1%, n = 583). Using flash or positive blood aspirate to predict intravascular injections was 97.9% specific, but only 44.7% sensitive.
Conclusions: There is a high incidence of intravascular injections in transforaminal ESIs that is significantly increased at S1. Using a flash or blood aspiration to predict an intravascular injection is not sensitive, and therefore a negative flash or aspiration is not reliable. Fluoroscopically guided procedures without contrast confirmation are instilling medications intravascularly and therefore not into the desired epidural location. This finding confirms the need for not only fluoroscopic guidance but also contrast injection instillation in lumbosacral transforaminal ESIs.