The FDA review of the epidural shots is being conducted by the agency’s Safe Use Initiative, which was created in 2009 to reduce “preventable harm” caused by medications, according to the report. Meanwhile, other physicians are trying to get the word out about the techniques that contribute to serious complications, such as paralysis. This is extremely important as concentrating solely on the medication rather than the technique itself may lead to erroneous conclusions and significantly effect patient care.
Scott Glaser, MD, an interventional pain management physician and president of the Pain Specialists of Greater Chicago in Burr Ridge, Ill., has conducted research into the cause of paraplegia in patients who receive transforaminal epidural steroid injections (TFESI) in the lumbar and thoracic areas of the spine. He says the problem with this procedure, which has “caught on like wildfire” among pain physicians over the last decade, is a stubborn and ill-advised adherence to an approach known as the “safe” triangle.
According to Dr. Glaser, the “safe” triangle” refers to a fluoroscopic region just lateral to the inferior margin of the pedicle, dorsal to the vertebral body and cephalad to the nerve root. Because needle placement in this area avoids the nerve root, the zone was originally and, unfortunately according to Dr. Glaser, named the “the safe triangle”. This approach is advocated as the standard of care by the International Spine Intervention Society and has been widely disseminated through guidelines, seminars and videotapes.
While physicians effectively avoid the nerve root by using the ‘safe’ triangle for epidural steroid injections, Dr. Glaser says this approach introduces another and more devastating risk: encountering the radicular artery, which lies close to the spinal nerve. This artery can be found in any foramen and is always located in the superior and anterior aspect of the foramen- the same region as the “safe triangle” approach calls for placement of the needle. When the needle is placed in the “safe triangle” and even when all normal precautions are followed according to guidelines, the needle can damage or even completely sever the artery or embolism can occur, resulting in severe complications related to spinal cord damage including paralysis.
“The physicians who developed this very effective procedure called it the ‘safe’ triangle because they were avoiding the nerve,” Dr. Glaser says. “The procedure was taught and widely and uncritically adopted without truly vetting the possible complications. The original articles and videotapes never even mentioned the vascular contents of the foramen.”
Dr. Glaser believes that this complication has not been adequately addressed for several reasons. First, the number of patients who experience paraplegia following transforaminal epidural steroid injections is relatively low. “It’s such a rare event compared to the number of transforaminals that have been performed,” Dr. Glaser says. “There were over 300,000 transforaminal injections performed on Medicare beneficiaries alone in 2006 and currently there are only 19 cases [of paraplegia] reported in the literature.” He says in looking at complication rates, physicians and researchers may tend to focus too heavily on the preponderance of uncomplicated procedures rather than the rare cases of paraplegia.
In a report co-authored with Rinoo V. Shah, MD, Dr. Glaser wrote, “Different practitioners have developed strategies to protect against TFESI-associated paraplegia while still using the safe triangle technique. Unfortunately, it appears they are trying to salvage a specific technique that is fatally flawed”. Dr. Glaser and Dr. Shah believe that many of these practitioners suffer from ‘survivorship bias’ — the logical error focusing on the millions of survivors of TFESIs and not on the rare paraplegias stemming from TFESI.”
He added that when paraplegia complications are analyzed, physicians explain and rationalize the cause of complications in hindsight, “as if it had been expected.” For example, the physician may be criticized for placing the fluoroscope in the incorrect position. In Dr. Glaser’s opinion, blaming paraplegia following transforminal epidural steroid injections on operator error is an example of sophistry- superficially plausible but generally fallacious. Because of this, he advocates abandoning the safe triangle approach altogether in the name of patient safety as the procedure can be performed in other areas of the foramen thus avoiding the possibility of encountering the artery.
He says the procedure could be performed more safely when the needle is placed elsewhere in the foramen — specifically, below the nerve root and behind the disc. Dr. Glaser suggests that instead of adhering to the ‘safe’ triangle, practitioners should adopt a retrodiscal approach described by Parviz Kambin, MD, known as “Kambin’s triangle.” This triangle is a right triangle that overlies the dorsolateral disc. In this triangle, the hypotenuse is the exiting nerve, the base is the caudad vertebral body and the height is the traversing nerve root. He says several studies have supported the use of Kambin’s triangle for endoscopic foraminotomies with or without laser assistance, and the relative safety of the procedure may also support the safety of the Kambin triangle TFESI. He has been using this technique for almost a decade after paralyzingly a patient using the “safe triangle” technique. He has not had a complication after performing thousands of transforaminal epidural steroid injections using this technique.
If elective TFESI were performed in a different location, such as Kambin’s triangle, Dr. Glaser is assured the occurrence of paraplegia due to vascular injury would decrease substantially. He bases this on the simple fact that the artery supplying the spinal cord will never be encountered during the procedure. “These procedures can be done just as safely as any other procedure by placing the needle anywhere in the foramen besides the safe triangle,” he says. “Avoiding the artery altogether protects you from all possible causes of injury.”
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