To the Editor:—
We read with interest the two case reports by Dr. Heavner et al. 1in which the introduction of an epiduroscope for placement of hyaluronidase, local anesthetic, and steroids in the lower lumbar epidural space led to the apparent disruption of venous wall integrity. Unintended vascular uptake of dye was documented on fluoroscopy. The case reports raise several concerns about the value of using an epiduroscope to place medication in this manner.
The evidence in the literature does not support the practice of using an epiduroscope to perform a caudal injection as a means to improve outcome, when compared with a fluoroscopically guided injection via a catheter or needle.2
As these case reports portray, use of an epiduroscope clearly offers no protection against vascular trauma. Indeed, the view through the scope gave no indication in either case that vascular wall integrity had been broached. It was fluoroscopic imaging in conjunction with dye administration that diagnosed the inadvertent injection.
Rather than protecting against trauma, it is reasonable to assume that the larger instrument (the epiduroscope is blunt, rigid, and 2.8 mm in diameter; a 20-gauge epidural catheter is softer and less than 0.9 mm in diameter) would be more likely to cause trauma. Indeed, Heavner et al. suggest that it is the lack of a low-pressure alternative route for the injectate to escape around the vessel that drives injectate into the vein. An epidural catheter, taking up less space, would allow more avenues of egress for the injectate and would be less likely to traumatize the vessel (smaller and softer) or lead to a high-pressure environment that would distend the vessel breach and induce this unwanted vascular ingress of medication.
The cost and charge to the patient of the fluoroscopically guided epiduroscope-based epidural injection is higher than a fluoroscopically guided needle or catheter injection.
Because a catheter is as effective, is less expensive, is less traumatic, and uses the only imaging technique (fluoroscopy) that provides safety in this injection, we must ask: Where is the value in using an epiduroscope to inject medication into the lumbar epidural canal?
The concept of introducing a flexible fiberoptic scope into the epidural space to directly visualize structures is appealing. Ideally, we could accomplish this safely, be able to clearly define normal and abnormal anatomy, and use the anatomical information to improve treatment by providing directed therapy. These goals have been elusive, despite the availability of this technique for more than 20 yr.3The current case reports1are a clear reminder that the risks and benefits of this technique have yet to be clearly established. We believe that safety and cost dictate that the routine use of epiduroscopy to “guide” caudal injection not be used until evidence generated by randomized controlled trials proves that it provides benefit sufficient to warrant the additional trauma, risk, and cost it obviously incurs.
*The University of Iowa, Iowa City, Iowa. douglas-merrill@uiowa.edu
