January 19, 2015

Epidural injections and particulate steroids

Epidural steroid injections are commonly used to treat low back pain, neck pain, radicular pain, and radiculopathy.  This pain can come from a variety of causes, including disc herniation, spinal stenosis, post lumbar surgery syndrome, lumbar degenerative disease or cervical degenerative disease, also known as spondylosis, and degeneration of the discs.  Recently, the FDA caused a furor when the agency issued a warning that serious complications could arise from epidural steroid injections.  The FDA focused on something called “particulate” steroids, meaning steroids that are in solution with microscopic crystals.  The concern was that if these steroids got into the arterial blood stream, they could cause what is known as an embolic stroke, in which the particles of steroid block blood flow, causing a stroke downstream from the occlusion.  Think of a multicar pile up on the freeway.

As evidence, they point to the preponderance of reports stroke cases having occurred when particulate steroids are used.

There are several problems with the FDAs position.  Firstly, it does not explain why four of the cases where there was a stroke occurred with non-particulate steroids. With this formulation, there are no microscopic crystals which can clump together and block blood flow.  It is very important when you exam a possible explanation for a problem to explain the cases which do not fit under your theory.  In this case, the theory that particulate steroids cause a stroke by crystals aggregating in the blood stream does not explain the strokes that occurred when there were no crystals to aggregate.  This fact is a blow against the particulate steroid theory.

There is another theory which is that the needle hits the muscle in the wall of the blood vessel, causing the artery go into spasm.  This theory, which has other arguments to support it, such as the size of the needle would not easily fit into the opening, or lumen, of the blood vessel.  The way to avoid these problems is to use blunt needles, which cannot cause spasming of the artery.  There has been no reported case of a stroke with blunt needles.

The American Society of Interventional Pain Physicians has proposed new codes for epidurals, with and without steroids, to track these complications.