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Fluoroscopy and Cervical Epidural Steroid Injection
Onassis Caneris, M.D., a physician from New England Neurological Associates, co-authored and recently published a paper entitled “The Role of Fluoroscopy in Cervical Epidural Steroid Injections” in the journal Spine. Dr. Caneris’ colleagues in the study are Milan P. Stojanovic, M.D., To-Nhu Vu, M.D., Jan Slezak, M.D., Steven P. Cohen, M.D., and Christine N. Sang, M.D.
Dr. Caneris, a neurologist with specialized training in anesthesia and pain management, and his colleagues noted that patients suffering from acute and chronic pain of the head, neck, and upper extremities often undergo steroid injections to help overcome their condition. The question posed by the investigators concerns the effectiveness of fluoroscopic guidance in
determining and delivering the steroid medication to the appropriate neuroanatomic locus.
The paper is the result of a multicenter study of cervical epidurograms that took aim at analyzing how well the loss of resistance technique (LOR) identifies the epidural space and at describing the characteristic distribution of epidural contrast during cervical epidural steroid injections.
Previous Studies
No previous epidurographic studies of cervical epidural steroid injections have been established to date. In earlier studies of lumbar epidural steroid injections, however, the LOR technique when performed without fluoroscopy has been shown to result in inaccurate needle placement at up to a 30% rate.
The Loss of Resistance Technique
The loss of resistance technique (LOR) is the most widely used method in clinical practice of identifying the epidural space. With LOR, the telling factor during epidural needle and catheter placement is the loss of resistance to air or saline. Most often this technique has been performed “blind,” that is without the benefit of the fluoroscope or other imaging. Blind procedures have been shown to produce false positives at about a 30% rate. Other researchers discovered that in blind lumbar epidurals about 50% missed the intended level. Mistaken needle placement means ineffective delivery of medicine and more pain for patients.
The spinal cord and associated anatomy is more closely confined in the cervical region than it is in the lumbar region, with a resulting smaller volume of epidural space. The difficult anatomy of the cervical region likely leads to even more false LOR positives and misidentification of the area of pathology than in the lumbar region.
The Value of Fluoroscopic Guidance
When identifying the epidural space prior to a steroid injection, the use of fluoroscopy improves the accuracy of needle placement and the subsequent delivery of steroid medication directly to the identified pathological area. With fluoroscopic guidance, fewer attempts will be needed to find the epidural space, which means less discomfort for patients, and a finally accurate placement in virtually 100% of cases. The need to sedate patients because of anxiety is also reduced with the use of fluoroscopy, and patients who are conscious are better able to report on the process they are undergoing. This reduces the level of risk to the patient during injection. Use of fluoroscopy during epidural steroid injection procedures allows for more accurate injections and reduces the amount of pain experienced by patients.
Representative fluorograph. Lumbar AP view; treatment for symptomatic right S1 radiculopathy. Illustrates medication being administered to right S1 spinal nerve.
The Study
The cervical epidural steroid injections were performed at an academic center and two pain management clinics. Subjects were selected from among those patients who presented with cervical radiculopathy and MRI findings that included herniated nucleus pulposus, spinal stenosis, or evidence of disc degeneration. The procedures all followed a similar protocol in terms of how the patients were positioned, the angle, frequency, and number of fluoroscopic images, the process of performing the LOR contrast, and delivery, and the injection of steroid medication.
After numbing the patient’s skin with lidocaine, a needle was inserted into the cervical area as determined by the senior physician. Fluoroscopic images were taken as the needle advanced, and, when LOR was thought to be located in the epidural space, contrast medium was injected and additional images were acquired at anteroposterior, lateral, and oblique angles. The physician then evaluated the location of the contrast medium, repositioning the needle if necessary. When the needle position was confirmed to be in the epidural space, then contrast medium was injected into the epidural space. Finally, steroid medication was injected at the precise location of the pathology.
Thirty-one patients had a total of thirty-eight procedures performed, with two patients having three injections and three patients having two injections. In 18 of the procedures the injection needle was identified by fluoroscopic imaging to be accurately located in the epidural space on the first approach (simulated “blind technique”). Fluoroscopy showed that 20 of the procedures needed a second attempt of which 14 successfully entered the epidural space. Further, four procedures needed a third attempt and one case needed a fourth attempt before accurately entering the epidural space.
In nineteen cases fluoroscopic images showed that the contrast medium spread only unilaterally. In none of the cases was any contrast found intrathecally. And in every case, with eventual full use of fluoroscopy, the steroid injection was applied to the area of pathology.
Conclusions of the Study
The “simulated blind” loss of resistance technique produced a high rate of false positives (53%), which were identified through fluoroscopic imaging. The inherent difficulty of the cervical anatomy may be, in part, a cause of the inadequate location of the initial injection of contrast medium. The large number of patients (51%) who attained only unilateral contrast spread strongly suggests that injections be done ipsilaterally to the patients’ cervical pain conditions, which is greatly aided by the use of fluoroscopy.The authors of the study recommend that fluoroscopy be used routinely with cervical epidural steroid injections. Without fluoroscopic guidance, practitioners have reduced awareness of false positive LORs, of unilateral distribution of contrast (and subsequent spread of steroid solution), of inaccurate needle placement, and of inaccurate medication placement. Fluoroscopic guidance enables accurate placement of steroid medication and the potential for more effective pain management.
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