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At least 35.5% of patients had no EMG evidence ofradiculopathy and another 19.7% were deemed to have “pos-sible radiculopathy.” Although all MRIs demonstrated im-pingement, only 42 patients had definite EMG evidence ofradiculopathy, leading to the conclusion that MRI findingsof impingement may be misleading in at least a third to half ofall patients and reducing the power of the study to resolveclinically significant differentiating factors. The study mayhave been more appropriately entitled with great merit, “Out-comes after lumbar transforaminal injections for EMG-proven radiculopathy.”

It is my personal observation that anterior transforaminalinjections, as demonstrated by injection of 2 ml of radio-graphic contrast agent, often outline only a single exitingnerve root. Radiculopathy can be the result of clinicalinvolvement of the exiting nerve root or of the traversingnerve root. Some radiculopathies treated by single-leveltransforaminal injection at the level of the disc pathologyare unhelpful, and many clinicians prefer two-level transfo-raminal injections.

Although the authors conclude that patients with EMGevidence of radiculopathy do have improved outcomes, it isleft for the reader to consider that patients who did not clearlyhave lumbar root pathology may not improve with such injec-tions. Although this finding may appear intuitively obvious,it should lead the reader to consider the importance of MRIfindings of impingement and alternative diagnoses, includingdiscogenic pain syndromes presenting with radiculopathy.

Although the Agency for Health Care Policy and Re-search questioned the use of epidural injections for severesciatica, one must appreciate the historical context more fully:Lumbar transforaminal injections were performed rarelybefore the 1990s, and it is unclear if such reticence is meritedwhen considering transforaminal injections today.

Lastly, a fine point of anatomy: The direct injection ofsteroid into the posterior epidural space is correctly referredto as an “interlaminar” injection, and unless a formal surgicalbreach of the osseous lamina has occurred, the term “trans-laminar” is inaccurate.

The recommendation for prospective study to determineappropriate treatment for any disorder requires precisecase definition to allow one to differentiate among causesof “sciatica” and “radiculopathy” and should be based ondetailed clinical, electrophysiologic and imaging findings,in addition to the usual occupation, insurance and demo-graphic indicators.

Reference

[1] Tong HC, Williams JC, Haig AJ, Geisser ME, Chiodo A. Predicting out-comes of transforaminal injections for sciatica. Spine J 2003;3:430–4.

Jeffrey D. Petersohn, MDLinwood, NJ

doi: 10.1016/j.spinee.2004.03.005

Author’s Reply to Dr. Petersohn

We want to thank Dr. Petersohn for his insightful com-ments. In reviewing our manuscript we agree we were notclear in several areas, and we are grateful to The SpineJournal for allowing us to address these issues.

Our manuscript said, “every patient had an imaging studydone to document the presence of nerve root impingement.”We were remiss in not clearly reporting the inclusion criteria.We included only subjects who had a clinical presentationof sciatica and accompanying signs and symptoms consistentwith a radiculopathy confirmed by imaging evidence ofnerve root impingement in the expected location. We couldnot be more specific in this retrospective study becausedifferent clinicians used different neurotension signs andother physical examination tests to diagnose radiculopathy.

We changed the word “radiculopathy” to “sciatica” inthe title and the discussion just before submission becausethere was some argument whether we could definitively saythe subjects had a radiculopathy using retrospective data. Inhindsight, what we should have done was replace “radiculo-pathy” with “clinically diagnosed lumbosacral radiculopathywith MRI confirmation.”

The third comment that the MRI scan may be misleadingbecause the electrodiagnostic study (EMG) showed definiteradiculopathy in only 55% of the subjects is incorrect. Aselectromyographers, we wish the EMG study would be adefinitive study with great sensitivity and specificity forradiculopathies. However, the American Academy of Elec-trodiagnostic Medicine consensus statement estimated thesensitivity of the EMG study for cervical radiculopahy tobe 51% to 72% [1]. The sensitivity for lumbosacral radicu-lopathies is probably similar. Because we did our univariateanalysis and regression analysis including subjects with andwithout EMG-confirmed radiculopathy, we cannot title thearticle “Outcomes after lumbar transforaminal injections forEMG-proven radiculopathy.” As noted above, we shouldhave titled it “ Predicting outcomes after lumbar transforami-nal injections for clinically diagnosed lumbosacral radiculo-pathy with MRI confirmation.”

The author’s comments that sometimes it is more benefi-cial to do two-level transforaminal epidurals for paracentraldisc herniations is an interesting comment. Before I go on,I should say we also sometimes do two-level transforaminalepidurals for the same reason. This observation cannot besupported or refuted by our nonrandomized cohort study,and I would caution Dr. Petersohn about relying on anecdotalexperience. The literature is full of situations where anec-dotal reports and nonrandomized cohort studies suggestedan intervention was beneficial, but then randomized con-trolled trials did not show any benefit [2,3]. I used to think,probably because of selective memory, that my physicalexamination skills were so good I could reliably predict over90% of patients who would benefit from manual therapydespite studies to the contrary [4,5]. However, when I lookedat my results objectively, the odds ratio of my physical

Special Features / The Spine Journal 4 (2004) 604–607 607

examination predicting benefit from manual therapy was 1.4[6]. We would appreciate it if anyone would conduct arandomized study to answer this question. The two possiblequestions that could be asked are 1) does initially tryingtwo-level transforaminal epidurals have benefit over single-level epidurals, and 2) if a patient does not benefit from asingle-level transforaminal epidural, does repeating a two-level epidural have benefit over repeating with a single-level epidural?

It is nice to see that Dr. Petersohn is an advocate forelectrodiagnostic studies. We are electromyographers andwanted to say the EMG study definitively helped predictoutcomes from epidural injections. However, because theEMG results were not significant in the regression analysis(possibly because of confounding) we could not say that.At best, this study suggests only that the EMG study maypredict outcomes. Still, this is a start because we are notaware of any other study evaluating whether EMG studypredicts outcomes from epidurals. We could have said theEMG study predicted outcomes if we reported only the find-ings of the EMG study alone, but this would be unethical.

The comment that the Agency for Health Care Policyand Research (AHCPR) questioned the use of epidural injec-tions is a little removed from the scope of this paper. Weagree that the AHCPR recommendations should not applyto transforaminal epidural injections. There have been atleast two good studies of blinded randomized controlledtrials for transforaminal epidurals. The smaller one, withless formalized outcome measures (ie, percent of patientswho went on to have surgery), showed benefit, whereas thelarger, better-designed study did not show benefit [7,8].

Dr. Petersohn is correct that “interlaminar” is more accu-rate than “translaminar.” However, the word translaminar iscommonly used. In the Guidelines for the Performance ofLumbar Spinal Injection Procedures, adopted by the Interna-tional Spine Injection Society on August 12, 1999, theprocedure is called “lumbar translaminar epidural injection.”

In a recent review article, the author tried to please bothgroups by using the word “translaminar/interlaminar” [9].

Finally, we agree that a prospective study looking atpredictive factors for epidural injections should be betterorganized and designed to address potential confoundersthat our retrospective study could not. We wish to againthank Dr. Petersohn for his insightful comments.

Henry Tong, MD, MSAnn Arbor, MI

References

[1] American Association of Electrodiagnostic Medicine, American Acad-emy of Physical Medicine and Rehabilitation. The electrodiagnosticevaluation of patients with suspected cervical radiculopathy: literaturereview on the usefulness of needle electromyography. Muscle Nerve1999;22:S213–21.

[2] Pocock SJ. Clinical trials: a practical approach. Chichester [WestSussex]; New York: Wiley; 1983.

[3] Friedman LM, Furberg C. Fundamentals of clinical trials. 3rd ed. St.Louis: Mosby-Year Book; 1996.

[4] Dreyfuss P, Michaelsen M, Pauza K, McLarty J, Bogduk N. The valueof medical history and physical examination in diagnosing sacroiliacjoint pain. Spine 1996;21:2594–602.

[5] Slipman CW, Sterenfeld EB, Chou LH, Herzog R, Vresilovic E. Thepredictive value of provocative sacroiliac joint stress maneuvers inthe diagnosis of sacroiliac joint syndrome. Arch Phys Med Rehabil1998;79:288–92.

[6] Tong HC, Briggeman AR. Using the pain drawing and test manualtherapy treatment to predict short-term manual physical therapy out-comes for low back pain. In: K30-TPCR Annual Symposium; May 2,2003; Ann Arbor, Michigan.

[7] Riew KD, Yin Y, Gilula L, Bridwell KH, et al. The effect of nerve-root injections on the need for operative treatment of lumbar radicularpain. A prospective, randomized, controlled, double-blind study. J BoneJoint Surg Am 2000;82-A:1589–93.

[8] Karppinen J, Malmivaara A, Kurunlahti M, et al. Periradicular infiltra-tion for sciatica: a randomized controlled trial. Spine 2001;26:1059–67.

[9] Botwin KP, Gruber RD. Lumbar epidural steroid injections in the patientwith lumbar spinal stenosis. Phys Med Rehabil Clin N Am 2003;14:121–41.

doi: 10.1016/j.spinee.2004.03.004