Anesth Analg 1999;88:240
© 1999 International Anesthesia Research Society
EDITORIALS
Epidural Steroids in Treating Failed Back Surgery Syndrome
John Rowlingson, MD
Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
Address correspondence to John Rowlingson, MD, Department of Anesthesiology, University of Virginia Health System, PO Box 10010, Charlottesville, VA 22906-0010.
Pain is a multidimensional experience with (at least) biomedical and psychosocial, cultural and religious, and cognitive and affective aspects about which much is written. In this issue of the Journal, Fredman et al. (1) present a study of 50 patients with failed back surgery syndrome (FBSS) in whom the ease of reaching the epidural space using a loss of resistance to air technique was assessed and the accuracy thereof confirmed by fluoroscopy. Their article offers precious insight into some of the fundamental principles of chronic pain evaluation and management. They acknowledge in passing (without providing any indication of explicit patient assessment) the influence that myriad psychosocial factors can have in chronic pain patients—the implication being that these data are crucial in selecting patients for invasive diagnostic and/or therapeutic procedures. They highlight the importance of a physical examination of the patient by observing the difficulty in accurately identifying the anatomic level of both the patient's pathology and the specific vertebral level for needle placement (which is viewed as vital to gaining appropriate delivery of therapeutic medication). They use the term FBSS (chronic, debilitating low back pain occurring in a patient after back surgery of a variety of types, such as diskectomy, laminectomy, and lumbosacral fusion, that was unsuccessful in relieving the patient's symptoms) to describe the particular chronic pain problem of their patients. This could stand as a catch-all label, as it seems a number of chronic pain syndrome titles do, were it not reasonably defined so that readers understand more clearly who was studied.
That nerve blocks are the most common intervention provided by anesthesiologists is not news, nor is the fact that with their acquired experience, most pain management techniques can be performed without the benefit of radiographic guidance. However, there has been a growing appreciation that placing needles in certain patients is more accurate when such techniques are used. Stewart et al. (2) reported in 1987 that performing epidurography in patients presenting for epidural steroid injections had definite value by documenting both needle location and a pathological entity. Fredman et al. (1) critique the use of fluoroscopy in the management of their patients with FBSS; they found it to be most valuable not in locating the epidural space, but rather in verifying the inaccessibility of the target tissue. In this day and age of heightened awareness about cost containment, this is a most valuable aspect of their study. The use of fluoroscopy adds expense and complexity to patient care because it requires technical assistance and equipment to be available; scheduling issues to come into practical consideration; and special training of the pain medicine practitioner is required. These issues entangle the care of patients with chronic pain, yet the additional costs must be justified.
FBSS reflects the failure to achieve a satisfactory result after a lumbosacral spine surgical procedure (3). Loeser et al. (3) state that this can occur because of an incorrect diagnosis (including poor patient selection based on the presence of entrenched illness behaviors and interfering psychosocial factors), improper/inadequate surgery (such as not decompressing the nerve roots enough or failure to recognize the significance of concurrent stenosis), or complications of the surgery or a diagnostic procedure (such as surgical trauma, infection, or bleeding contributing to the evolution of arachnoiditis). The differential diagnosis for FBSS is substantial and includes diskitis, recurrent/new herniated disc, arthritis, osteomyelitis, spinal or fusion stenosis, spinal instability, fusion pseudoarthrosis, epidural scarring, degenerative disc disease, facet arthropathy, muscle spasm, myofascial pain, neoplasm, osteoporosis, and psychological and environmental factors. Obviously, based on the implications made by Fredman et al. (1) and the sage wisdom of Loeser et al. (3), it is essential that patients with FBSS be evaluated thoroughly to establish that they are appropriate for interventional therapy because this modality is not indicated in many of the above-mentioned conditions.
Fredman et al. (1) found that, despite the conventional teaching that placing needles through postoperative scar tissue is fraught with difficulty, the number of attempts required for them to do so was very respectable. Also in contrast to popular opinion was the finding that, in a large proportion of patients (44 of 48), after their surgical procedure, the identification of the epidural space using a loss of resistance to air technique was accurate. Given the report of Katz et al. (4), in which injected air caused a significant headache, one may wonder whether air is the best substance to use in this group of patients, for whom the wet tap rate may be as high as 20%. What was problematic in Fredman et al.'s group of patients was correctly identifying the vertebral level for needle placement, both as it was derived from the patient's clinical signs and symptoms and in exactly locating the level anatomically on the patient's back. Another critical issue revolved around getting enough spread of the contrast dye to the level of pathology (which is clinically relevant to placing the therapeutic drugs precisely). In only 26% of the patients did a 5-mL injectate bolus reach the perceived target tissue, despite the authors' stated goal of depositing the steroids at the level of pathology. This is the decisive information concerning the use of fluoroscopy in patients with FBSS to be extracted from this article.
That the radiologic evaluation of patients who have undergone spine surgery is complicated is well documented (5,6). Scarring and adhesions in the epidural space probably contribute to the patient's symptoms (although establishing a definitive association between the pathologic changes found and the symptoms is very difficult ) (zref>(3)(zrefx>, but they certainly confound the interpretation of radiographic studies and interfere with the distribution of injected drugs. The authors spectulate that there may be a relationship between the extent of surgery and the subsequent degree of fibrosis and adhesion formation, but this is unproven. It is clear from their article that the anatomic alteration of the surface anatomy of the low back after spine surgery markedly complicated identifying the desired vertebral level for needle placement. Fluoroscopy revealed the lack of significant correlation between both the perceived level of pathology, as determined by the patient's symptoms and physical examination findings, and the clinician's placement of the needle at that level, based on the surface anatomy. Obviously, back surgery distorts the patient's specificity of complaints, as well as the anatomy for determining needle insertion sites. Does placing the patient in the lateral decubitus position further complicate the situation? Furthermore, although it is unlikely that the results of this study were influenced in any way by injection of the contrast medium through a catheter rather than needle, one wonders whether the additional step of threading a catheter risks movement of the needle from an accurate location to an anatomically insignificant one and whether a catheter is more easily misdirected by dense scar tissue than a rigid needle.
A parallel feature of Fredman et al.'s article (1) is the importance of assessing the patient with FBSS. The patient's history and physical examination findings may only moderately contribute to correctly identifying the spinal level of pathology, but these data can be productively supplemented by radiological studies and surgery records. One may question whether depot steroids are "commonly administered" (for their antiinflammatory effects) in patients with FBSS, as Fredman et al. (1) contend. It is true that the optimal response to such therapy is achieved when the drugs are placed in closest proximity to the pain source. Others view this syndrome as being more characterized by neuropathic pain features and suggest treatment with anticonvulsants, antidepressants, baclofen, and opioids (3,6). Loeser et al. (3) advised a thorough work-up including orthopedic and neurosurgical consultation, followed by a program of physical and behavioral therapy. North and Roark (7) conscientiously present the neurosurgical view of management for this syndrome and note that FBSS is the most common chronic pain syndrome for which spinal cord stimulation therapy is used in the United States.
Fredman et al. (1) focus on the regional analgesia technique of epidural steroid injection in a group of patients for which pain management can be difficult. They indicate that patients do have an epidural space after spine surgery and that accurate needle location is not as problematic as once thought. However, these realities do not guarantee success, even with a well practiced therapy such as epidural steroid injections, as was so poignantly evidenced by the use of fluoroscopy. The pain medicine literature needs more evidence- and outcome-based studies. Fredman et al. (1) frame the value of fluoroscopy by questioning its routine use in epidural injections in patients with FBSS. It can be an invaluable aid for documenting at the first procedure whether the necessary level of pathology can be reached by the epidural injection of medication. If this is not possible, the clinician would be redirected to alternate forms of injectional therapy or other pain management strategies, thereby making patient care more efficient, avoiding undue discomfort from nonproductive procedures, and saving healthcare dollars. This decision-making process would lead one to the approach advocated by Jacobson et al. (8), which encourages anesthesiologists to expand their role beyond the customary pain model of (acute) postoperative pain management. In so doing, we are exhorted to foresake the traditional biophysical view of pain (in which procedure-based therapies aimed at curing the pain are paramount) and to embrace the biopsychosocial construct (in which emphasis is placed on maximal reduction in and coping with pain, while restoration of functional capabilities is stressed). Fredman et al. (1) encourage us to critically review contemporary practices and to acknowledge their limitations while appreciating their genuine benefits.
References
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Calodney A. Failed back surgery syndrome. Pain Dig 1992;2:300–6.
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North RB, Roark GL. Spinal cord stimulation for chronic pain. Neurosurg Clin North Am 1995;6:45–61.
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Jacobson L, Mariano AJ, Chabal C, Chaney EF. Beyond the needle: expanding the role of the anesthesiologist in management of chronic non-malignant pain. Anesthesiology 1997;87:1210–8.[Web of Science][Medline]
Accepted for publication November 19, 1998.
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