Correspondence
Corticosteroid Injections for Sciatica
N Engl J Med 1997; 337:1241-1243October 23, 1997
- Article
To the Editor:
Carette et al. (June 5 issue)1 studied the efficacy of epidural methylprednisolone injections in patients with sciatica due to a herniated nucleus pulposus. After three and six weeks, the patients who received injections of corticosteroid reported less leg pain than those who received placebo. There were no differences in other outcome measures. Interpretation of this trial is hampered by the use of a placebo saline injection that differed in volume from the methylprednisolone injection: 1 ml as opposed to 10 ml. Some of the effect of epidural injections may be through the distention of epidural structures. The larger volume used in the methylprednisolone group may have resulted in greater distention and thus greater clinical benefit. As compared with placebo, epidural injections of corticosteroids may not produce even the short-term improvements in leg pain suggested in the paper.
1 ReferencesKarim Raza, M.R.C.P.
Guest Hospital, Dudley DY1 4SE, United Kingdom1
Carette S ,Leclaire R ,Marcoux S , et al. Epidural corticosteroid injections for sciatica due to herniated nucleus pulposus. N Engl J Med 1997;336:1634-1640
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To the Editor:
There are three basic approaches to performing an epidural injection of corticosteroids: transforaminal, translumbar, and caudal. Most spine-care experts perform injections under fluoroscopic guidance to confirm the position and the placement of the needle and to avoid complications.1 The specific technique chosen is based on the clinical presentation of the patient and the location of the disk. Carette et al. used the blind translumbar approach in all patients regardless of disk location, size, or clinical presentation. White et al. showed that nonfluoroscopically guided translumbar epidural injections of corticosteroids miss the epidural space 30.4 percent of the time.2 Current literature on epidural injections of corticosteroids would support using fluoroscopy, the most selective approach, and not repeating an injection if the needle was appropriately positioned.3
Epidural injections of corticosteroids offer a powerful tool for pain control but should be accompanied by therapeutic spine exercises to promote normal spine function and to avoid reinjury.
3 ReferencesMarc P. Orlando, M.D.
Marc O. Sherman, M.D.
University of Cincinnati Hospital, Cincinnati, OH 452671
Lennard TA. Physiatric procedures in clinical practice. Philadelphia: Hanley & Belfus, 1995:273.
2
White AH ,Derby R ,Wynne G . Epidural injections for the diagnosis and treatment of low-back pain. Spine 1980;5:78-86
CrossRef | Web of Science | Medline3
Alleva JT ,Geraci MC Jr ,McAdam FB . Trends in lumbar epidural injections: an International Spinal Injection Society survey. Arch Phys Med Rehabil 1996;77:920-920 abstract.
CrossRef
To the Editor:
Radiculopathic pain can have both irritative (from the leakage of disk nuclear material) and mechanical (from direct nerve compression) components. Epidural administration of corticosteroids has been suggested to affect the neural irritation, but it would not be expected to reduce the mechanical-compression component. Can Carette et al. analyze their data to examine functional improvement in patients with pain without neurologic deficits or the progression to surgery in patients with the least benefit from epidural corticosteroids?
. . . Another concern is the primary outcome measure. The Oswestry scale was developed and validated to study back pain; its validity or reliability with respect to leg or radicular pain is unknown.
Donald C. Manning, M.D., Ph.D.
University of Virginia, Charlottesville, VA 22908Margaret B. Hopwood, Ph.D.
MBH Consulting, Milwaukee, WI 53222To the Editor:
In the study by Carette et al., patients who did not report marked or very marked improvement at three or six weeks received either a second or third epidural injection of methylprednisolone. The duration of action of methylprednisolone is two weeks.1 By injecting the drug at three-week intervals, potential cumulative benefits were lost. Most successfully treated patients experience relief between four and six days,2 suggesting the use of a research design with injections at intervals of one to two weeks.
. . . No significant difference at three months between the methylprednisolone and placebo group was expected. The natural history of these lesions, without intervention, is one of pain for the first 3 months, which peaks at 6 weeks; complete resolution of the motor weakness within 6 to 12 months; and partial or full recovery of any sensory loss by 1 year (if the onset of palsy is dated with the onset of paresthesia corresponding to the nerve-root level indicated by the signs and symptoms).3 Only 29.5 percent of the methylprednisolone group and 28.8 percent of the placebo group had motor deficits at base line. The natural history of sciatica without a specific single-nerve-root palsy due to a herniated nucleus pulposus is less clear.
This study used a heterogeneous group of patients. It would be interesting to investigate the results in terms of pain relief, change in function, and the need for surgery in the subgroup of patients with documented motor deficits who had received a series of one to three injections at intervals of one to two weeks, with the injections being given until the patients reported a more than 90 percent subjective improvement in pain.
3 ReferencesJean H. Gillies, M.D.
John H. Ward, M.D.
St. Paul's Hospital, Vancouver, BC V6Z 1Y6, CanadaDonald E. Griesdale, B.Sc.
University of British Columbia, Vancouver, BC V6Z 1Z3, Canada1
Burn JM ,Langdon L . Duration of action of epidural methyl prednisolone: a study in patients with the lumbosciatic syndrome. Am J Phys Med 1974;53:29-34
Medline2
Cuckler JM ,Bernini PA ,Wiesel SW ,Booth RE Jr ,Rothman RH ,Pickens GT . The use of epidural steroids in the treatment of lumbar radicular pain: a prospective, randomized, double-blind study. J Bone Joint Surg Am 1985;67:63-66
Web of Science | Medline3
Ombregt L, Bisschop P, ter Veer HJ, Van de Velde T, eds. A system of orthopaedic medicine. London: W.B. Saunders, 1995:48, 547-59.
Author/Editor Response
The authors reply:
To the Editor: We agree with Orlando and Sherman that epidural injections should ideally be performed with fluoroscopic control. This approach, however, is very rare in clinical practice, which is why we chose not to use fluoroscopy for our trial. In the absence of radiographic guidance, we cannot rule out the possibility that some of the injections may have been misplaced. However, the fact that we performed up to three injections in each patient greatly reduces the probability of any patient's not receiving at least one injection in the epidural space. Orlando and Sherman's assertion that therapeutic spine exercises are necessary to promote function and avoid reinjury is not supported by scientific evidence.1,2
To the best of our knowledge, no instrument has been validated specifically to assess functional impairment in patients with radicular pain. We chose the Oswestry Low Back Pain Disability Questionnaire because of its known reliability and validity in the study of back pain, but we modified it slightly by adding “and/or leg” to all statements that contained the word “back.” The Oswestry scores at base line showed a good correlation with the visual-analogue scores for assessing leg pain (r = 0.42, P<0.001) and the overall scores on the Sickness Impact Profile (r = 0.61, P<0.001). There was also a strong correlation between the changes in the Oswestry scores and the perceived degree of overall improvement or deterioration at three weeks (r = 0.98, P<0.001), thus supporting the validity of this instrument in the context of radicular pain.
In response to Gillies et al.: we found no difference in the efficacy of methylprednisolone injections in terms of pain relief and functional improvement between patients with and those without motor deficits. The difference between the methylprednisolone group and the placebo group in the mean degree of improvement in leg pain at three weeks was -11.2 in the patients with a motor deficit and -7.3 in those without (test for interaction, P = 0.70). However, these results should be interpreted with caution because of low statistical power.
Raza correctly points out that the improvement in leg pain observed in the methylprednisolone group could be explained by a distention of the epidural structures rather than by any action of methylprednisolone itself. The potential beneficial effect of volume distention is precisely why we chose to inject only 1 ml of saline in the comparison group in order to have a true placebo group. We agree that corticosteroids alone, as compared with placebo, may be even less effective in improving leg pain than what is suggested by our results.
2 ReferencesSimon Carette, M.D.
Sylvie Marcoux, M.D., Ph.D.
Centre Hospitalier Universitaire de Québec, Ste.-Foy, QC G1V 4G2, CanadaRichard Leclaire, M.D.
Hôpital Notre-Dame, Montreal, QC H2K 1C1, Canada1
Koes BW ,Bouter LM ,Beckerman H ,van der Heijden GJ ,Knipschild PG . Physiotherapy exercises and back pain: a blinded review. BMJ 1991;302:1572-1576
CrossRef | Web of Science | Medline2
Faas A . Exercises: which ones are worth trying, for which patients, and when? Spine 1996;21:2874-2879
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