Comp Clues


Steroid Injections: Interview with a Neuroradiologist

Date: 09/01/2003

Many of us wonder about the efficacy and cost effectiveness of widespread spinal steroid injections.  In order to obtain up to date information, I recently interviewed a physician who performs these frequently.  Dr. Robert H. Dorwart, a respected neuroradiologist, is Medical Director for the Center for Diagnostic Imaging.  Dr. Dorwart is a member of the American Society of Spine Radiology, the International Spine Injection Society, the American Society of Neuroradiology, the American College of Radiology and many more respected professional organizations.  He is a recognized leader in MRI and CT interpretations as well as, in diagnostic and therapeutic procedures.  Some of the most highly respected spine surgeons in Indianapolis, IN, where Dr. Dorwart practices, utilize his expertise by referring patients for spinal injection procedures.

Dr. Dorwart stated that most of the steroid injection procedures he performs are ordered relative to the following diagnoses:  A herniated disc with or without nerve root compression, spinal stenosis, chronic disc degeneration, and a bulging disc with nerve compression.  Almost all have been classified as having chronic spinal caused pain, with imaging studies sometimes done elsewhere, confirming the diagnosis.  Chronic pain is defined as having lasting for over 4-6 weeks, and with the patient having failed other conservative treatment such as NSAIDS, oral steroids, and physical therapy.

Because the goal is to deliver the steroid as perfectly as possible to the area of inflammation and, given the normally occurring anatomic variations in patients, CT imaging is essential, in Dr. Dorwart’s opinion.  Proper placement is correlated with the imaging studies available and with input from the referring physician.  He stated the steroid only remains at the injection site for 24-48 hours and then success is dependent on the effectiveness of the residual anti-inflammatory effect .

Of the following – nerve root injections, facet injections, and epidural steroids – only the latter should even be considered without concurrent imaging.  And, Dr. Dorwart recommends ESI’s be done with imaging for more accuracy.  To support why, Dr. Dorwart quoted a study done involving only expert, experienced anesthesiologists who were asked to perform ESI’s.  They were asked to state when they were in the epidural space and then imaging was used for confirmation.  20% of the time, the doctor was not in the epidural space.  While no terrible harm is perhaps done, injecting the numbing agent mixed with the steroid, Marcaine or Lidocaine, into a vein (the most likely error made in the study) can result in no benefit and, make the patient queasy.  Inserting steroids into the thecal sac can even cause arachnoiditis.

If there is no good anesthetic (numbing) response after an injection procedure, it is not a good prognosticator of benefit.  This could occur as a result of:

-Scarring from prior surgeries.

-A disc herniation that is so large it makes absorption impossible due to blockage.

-The pain is discogenic thus, due to the tears inside the disc, which cause chemical changes and the injection has no potential for successful pain relief.

Dr. Dorwart says the “Rule of Three” is accepted best practice but he does not know the specific origin or how it evolved.  His personal criteria is the expectation that a patient will get at least 25 % pain reduction before undertaking further injections.  He suggests a minimum interval of at least two weeks.    Further, Dr. Dorwart feels the optimum success from these spinal injection procedures relies on excellent placement of the steroid, patient education (many times he is the first to provide an anatomic model or, show and explain to the patient their imaging films), and that outcome is also impacted significantly by the patient’s motivation, an issue sometimes in the Worker’s Compensation population.

In summary, Dr. Dorwart said imaging confirms the doctor is in a safe anatomic location and as close to the pathology as possible.  Currently, a universal formal treatment protocol for spinal injections is lacking, thus imaging is not mandatory.  In Dr. Dorwart’s “perfect world” he wonders if diagnostic studies done earlier to assure an accurate diagnosis, more proactive treatment involving pain relief (via injection), physical therapy and NSAIDS, might not decrease pain, time off work, result in fewer injections and avoidance of surgery except where clearly indicated.