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Electrodiagnostic Testing Before Epidural Steroid Injections
Point/Counterpoint
Electrodiagnostic Testing Before Epidural Steroid Injections CASE SCENARIO A.P. is a 37-year-old man who works loading crates at a hardware store; he developed a right foot slap and lateral lower leg pain after a long day of work. He was referred by his occupational health physician, who suspected lumbar radiculopathy. Initially, the patient worked with a physical therapist, who was able to centralize some of the patient’s symptoms from the patient’s lower leg into the buttock but never was able to fully centralize the symptoms. His foot slap is improving, but he still notices some increased fatigue of his tibialis anterior at long days of work. Because of the persistence of symptoms despite 6 weeks of physical therapy, the patient was referred to you for further assessment, and a magnetic resonance imaging of the lumbar spine was ordered. On examination, you note focal weakness of 4/5 strength in the tibialis anterior and the extensor hallicus longus, and with side-lying hip abduction. You also note a decreased medial hamstring reflex on the affected right side. The slump sit test did provoke symptoms on the right side that is improved with cervical extension. The remainder of the examination is normal. The magnetic resonance imaging reveals a neuroforaminal L5-S1 disk protrusion abutting the right L5 nerve root in the neuroforamen. The patient is interested in having an epidural steroid injection and is inquiring whether he should also have an electrodiagnostic study performed. Arguing that, yes, the patient should also have electrodiagnostic studies performed is Thiru Annaswamy, MD, MA. Arguing that, no, electrodiagnostic studies are not necessary is Robert W. Irwin, MD.
Guest Discussants: Thiru Annaswamy, MD, MA Physical Medicine and Rehabilitation Service, Dallas VA Medical Center, Dallas, TX Disclosure: 8A, AANEM (completed pilot study on EMG in Radiculopathy), AAPMR (completed pilot study on Lumbar Dorsal Ramus Syndrome), 8B, 2010 investigator in completed research study funded by AANEM.
Robert W. Irwin, MD Department of Rehabilitation Medicine, Miller School of Medicine, University of Miami, Miami, FL Disclosure: 8, NIDRR/DOE study SCI complications
Feature Editor: Gary P. Chimes, MD, PhD University of Pittsburgh Medical Center, Pittsburgh, PA. Address correspondence to: G.P.C.; e-mail: [email protected] Disclosure: nothing to disclose
Thiru Annaswamy, MD, MA, Responds I would submit that there are 2 main reasons why I would recommend that the patient described in the case scenario go through an electrodiagnostic evaluation (EDX) before being considered for a lumbar epidural steroid injection (LESI). The first reason is for diagnostic determination, and the second reason is for better prognostication. The main diagnostic question being considered in the case presented here is whether or not the patient, A.P., has a lumbar radiculopathy that affects the right fifth lumbar root (L5R). Charles Cho et al [1] mention in their elegant evidence-based review in the recently published American Association of Neuromuscular and Electrodiagnostic Medicine’s practice topic that, “In those cases with negative imaging findings or atypical clinical presentations, EDX evaluation is especially useful; whereas, in those with abnormal imaging findings, it serves a complementary diagnostic role. A correct diagnosis of lumbosacral radiculopathy is important for implementation of timely and appropriate treatPM&R 1934-1482/12/$36.00 Printed in U.S.A.
ments.” As such, in A.P.’s case, given the information at hand, there is a strong possibility of right L5R. However, there is still a diagnostic possibility of a common peroneal neuropathy (CPN) [2] on the right or the possibility of 2 concurrent diagnoses of L5R and CPN or the possibility of the controversial double-crush syndrome [3], with an initial diagnosis of L5R that subsequently leads to the development of CPN. Given these multiple diagnostic possibilities, it would be extremely useful to perform an EDX evaluation of A.P. at this time before proceeding with any further treatment or management plan. The case to be made here is that EDX is valid, reliable, and useful in differentiating among these diagnostic possibilities and firmly establishing the correct diagnosis. EDX evaluation has long been an extremely valuable tool in the diagnostic armamentarium for clinicians’ management of patients with lumbosacral radiculopathy (LSR) [1]. EDX evaluation for LSR has a considerably higher diagnostic yield than other techniques [4]. The nerve conduction studies © 2012 by the American Academy of Physical Medicine and Rehabilitation Vol. 4, 223-229, March 2012 DOI: 10.1016/j.pmrj.2012.02.006
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portion of the EDX evaluation is noninvasive and standardized, and provides a sensitive measure of the functional status of sensory and motor nerve fibers and, therefore, is valid and reliable in the evaluation of peripheral nerve functioning [5]. The needle electromyographic examination (NEE) part of the EDX has also been demonstrated to be highly objective and reliable in the evaluation of LSR [1,6]. NEE is the only procedure that can document physiological nerve root irritation and is the most sensitive test in detecting a nerve root lesion [7]. An optimal screen has been recommended for the number of muscles to be examined to achieve adequate diagnostic probability for making the diagnosis of LSR [8], which places the level of evidence that supports the use of EDX, especially the NEE portion, in the diagnostic evaluation of patients with LSR at a level II or higher, which is a desirably high level of evidence [9]. The clinical diagnosis of radiculopathy is best made when there is a combination of concurring history and physical examination along with magnetic resonance imaging evidence that supports a corresponding structural lesion causing nerve impingement as well as consensus reached by unanimous independent opinions of more than one physician [10]. In A.P.’s case presented here, there is near concurrence of the presenting history and physical examination, a fairly well concurring structural lesion on magnetic resonance imaging that demonstrates right L5R impingement but only one physician’s opinion that concurs with one physical therapist’s opinion. Although the above combination of diagnostic evidence is reasonably conclusive, it is still possible to firm up the diagnosis further so that some of the not-socongruent elements of the case presentation, as illustrated below, can be better clarified. The features of presentation in A.P.’s case are consistent with the diagnosis of right L5R, which demonstrates gradual and incomplete recovery except for the following 4 atypical features. First, acute development of right foot slap and lateral lower leg pain after a long day of work. This is an atypical acute presenting symptom for radiculopathy because radiculopathy typically presents with back and leg pain in addition to numbness and paresthesias in a dermatomal distribution, and rarely presents initially with weakness (and no other sensory symptoms besides pain) as it has in A.P.’s presentation. The reason for pain and other sensory symptoms such as numbness and paresthesias to be more common than weakness as the initial presenting symptoms in acute radiculopathy is that a lesion large enough to cause motor nerve fiber compromise (causing weakness) is also sufficient enough to cause damage to large afferent fibers that convey proprioception and touch [11]. However, peripheral nerve entrapments, for example, CPN, can present in a variety of ways, including motor predominant or sensory predominant symptoms [12]. Therefore, the absence of numbness in a dermatomal distribution, as in A.P.’s case, although is uncommon in L5R, can be a very characteristic feature in CPN,
due to the peculiar feature of fascicular sparing [2]. Second, in A.P.’s case, the mechanical diagnosis and therapy based physical therapy has had limited success in centralizing A.P.’s pain. Although this does not rule out radiculopathy, it certainly brings into question whether another diagnosis, such as CPN, is in play. Inaccurate diagnosis is one possible explanation of why a highly effective treatment option for acute lumbar radiculopathy, such as mechanical diagnosis and therapy, was not very effective in this case. Third, focal weakness of tibialis anterior and extensor hallucis longus can be features of L5R and CPN [2]. However, the lack of documented weakness in the posterior tibialis (ankle inversion) elicits the possibility of the diagnosis of CPN being in play. It is true that documented weakness of hip abductors points to L5R as the diagnosis, but clinical experience tells me that it is often difficult to assess hip abductor strength adequately due to overlay of pain. Therefore, although the combination of grade 4/5 weakness in the tibialis anterior, extensor hallucis longus, and hip abductors strongly points to L5R, the possibility of an alternate diagnosis, such as CPN, still has to be considered. Fourth, the medial hamstring reflex has been described as being useful in clinically localizing an L5R [13]. However, my clinical experience suggests that it is notoriously difficult to elicit and very unreliable. There are no published reports of the medial hamstring reflex’s inter-rater reliability. However, one can expect it to be lower than the inter-rater reliability of the knee jerk, which is surprisingly poor [14]. Therefore, in my opinion, an unelicitable right medial hamstring reflex in A.P.’s case does not carry much clinical significance. A.P. had a work-related injury. Due to the potential worker’s compensation and medicolegal issues involved in A.P.’s case, it is important to establish the diagnosis clearly without any ambiguity. Both work-related CPN and work-related L5R require equally appropriate management. However, if CPN is revealed as the diagnosis on EDX, an LESI would obviously not be the treatment of choice as the next step in A.P.’s case management. An LESI, subsequently, might still be useful for A.P. because he has a foraminal disk protrusion at L5 that might be amenable to an LESI; however, it merits a lesser priority now if the EDX evaluation supports the diagnosis of CPN. The second main reason why I would recommend that A.P. go through EDX before being considered for an LESI is so that I can better advise him on the expected outcome after LESI. There are 3 recent studies that have examined this particular issue. Fish et al [15] retrospectively studied the predictive value of the NEE portion of EDX for pain and functional outcomes in response to transforaminal epidural steroid injection in LSR. Consecutive subjects had their NEE before transforaminal epidural steroid injection at L4 and/or L5, and had symptomatic pain in only one extremity. They found significantly greater improvement of Oswestry Disability Index scores for NEE-positive radiculopathy (7.11 ⫾ 9.5)
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compared with a negative NEE (3.2 ⫾ 17.4; P ⬍ .05). Pain improvement, however, was not significantly different in the positive NEE group (1.8 ⫾ 1.2) compared with a negative NEE (1.2 ⫾ 1.2; P ⬎ .05). Another recently published study reported a retrospective chart review of patients who had LESI after NEE [16]. No differences were found among NEE positive, negative, and equivocal groups in the response rate to LESIs. The researchers concluded that patients with negative NEE should not be excluded from a trial of LESI. We performed a prospective, multiple regression study and found that abnormal NEE consistent with EDX impression of radiculopathy moderately predicted long-term improvement in pain after LESI [17]. Positive EDX evidence of radiculopathy was predictive of statistically significant better improvement in both pain and functional scores compared with no EDX evidence of radiculopathy, although the patients with normal NEE also tended to favorably respond to LESI [17]. A regression equation, including NEE and other independent predictors, was predictive of pain and functional outcomes [17]. The above research studies clearly support the prognosticating role that EDX has in addition to its well-established role of diagnostic confirmation of lumbar radiculopathy. In A.P.’s case, if his EDX study reveals an abnormal NEE consistent with L5R, then it would be predictive of better outcomes with LESI than if his EDX study was normal. In addition, an EDX study would also provide more details regarding the pathology (axonal versus demyelinating) and severity of the diagnosis, which might also come in handy later. Therefore, armed with the information gleaned from an EDX study, I would be able to more accurately and reliably advise A.P. as to what his diagnosis is and give him betterinformed prognostication information when I obtain his informed consent before giving him an LESI.
REFERENCES 1. Charles Cho S, Ferrante MA, Levin KH, Harmon RL, So YT. Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: An evidence-based review. Muscle Nerve 2010;42:276-82.
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2. Kang PB, Preston DC, Raynor EM. Involvement of superficial peroneal sensory nerve in common peroneal neuropathy. Muscle Nerve 2005; 31:725-9. 3. Schmid A, Coppieters M. The double crush syndrome revisited: A Delphi study to reveal current expert views on mechanisms underlying dual nerve disorders. Man Ther 2011;16:557-62. 4. Dillingham T. Electrodiagnostic medicine II: Clinical evaluation and findings. In: Braddom R, ed. Physical Medicine and Rehabilitation. 3rd ed. Philadelphia, PA: Saunders; 2006, 213. 5. England J, Gronseth G, Franklin G, et al. Distal symmetric polyneuropathy: A definition for clinical research: Report of the American Academy of Neurology, the American Association of Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. Neurology 2005;64:199-207. 6. Chouteau W, Annaswamy T, Bierner S, Elliott A, Figueroa I. Interrater reliability of needle electromyographic findings in lumbar radiculopathy. Am J Phys Med Rehabil 2010;89:561-9. 7. Nardin RA, Patel MR, Gudas TF, Rutkove SB, Raynor EM. Electromyography and magnetic resonance imaging in the evaluation of radiculopathy. Muscle Nerve 1999;22:151-5. 8. Dillingham T, Lauder T, Andary M, et al. Identifying lumbosacral radiculopathies: An optimal electromyographic screen. Am J Phys Med Rehabil 2000;79:496-503. 9. Oxford Centre for Evidence-Based Medicine. Levels of Evidence. Available at http://www.cebm.net; 2009. Accessed December 21, 2011. 10. Haig AJ, Tong HC, Yamakawa KS, et al. The sensitivity and specificity of electrodiagnostic testing for the clinical syndrome of lumbar spinal stenosis. Spine (Phila Pa 1976) 2005;30:2667-76. 11. Radiculopathies. In: Dumitru D. Electrodiagnostic Medicine. Philadelphia, PA: Hanley and Belfus; 1995, 539. 12. Sourkes M, Stewart J. Common peroneal neuropathy: A study of selective motor and sensory involvement. Neurology 1991;41:102933. 13. Jensen OH. The medial hamstring reflex in the level-diagnosis of a lumbar disc herniation. Clin Rheumatol 1987;6:570-4. 14. Stam J, van Crevel H. Reliability of the clinical and electromyographic examination of tendon reflexes. J Neurol 1990;237:427-31. 15. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 16. Marchetti J, Verma-Kurvari S, Patel N, Ohnmeiss DD. Are electrodiagnostic study findings related to a patient’s response to epidural steroid injection? PM R 2010;2:1016-20. 17. Annaswamy TM, Bierner SM, Chouteau W, Elliott AC. Needle electromyography predicts outcome after lumbar epidural steroid injection. Muscle Nerve 2012;45:346-55.
Robert W. Irwin, MD, Responds In our current health care system, the physician must balance the care of the patient with the ballooning cost of delivering this health care. Unlike in the past, when the physician may have ordered a whole battery of tests, some of which were not needed, today’s physician must balance the cost of that care with the benefits. In truth, often enough, the physician will order a test only to have the insurance company deny it as they try to cut costs. To add to these pressures, with the advent of direct-to-consumer advertisement and the growth of information accessibility on the Internet, patients often request certain tests and treatments that they believe they need, without fully un-
derstanding the pathophysiology of the health issue. Because of these pressures, now more than ever, the treating physician needs to make judicious use of the testing at hand. Dillingham [1] suggests that the utility of electrodiagnostic studies is to exclude other diagnoses that mimic radiculopathy. Electrodiagnostic studies may also suggest severity or extent of the disorder beyond clinical symptoms as well as solidifying the diagnosis when there are mild or nonspecific findings on imaging studies. He also notes that a positive electrodiagnostic study may be helpful in outcome prediction in surgical cases [1].
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In this case, the patient is interested in having an epidural injection. The question is whether there is any advantage to have an electrodiagnostic study before the injection. When assessing whether further testing should be performed, it behooves the physician to have goals in minds for ordering such tests. These should include the following: 1. How much does this test help in making and/or improving the diagnosis? 2. Does this test give me any information about prognosis or outcomes with respect to treatments? 3. Will results of this test change my treatment for this patient? How much does this test help in making the diagnosis? The purpose of obtaining a thorough history and physical examination is to better care for the patient and of testing is to augment this information. When opting to order additional testing, the physician should assess the need to enhance the information already gathered. Before deciding if an electrodiagnostic study should be performed, we should assess whether we believe that the workup performed so far is adequate. In this case, we should assess to what extent our history and physical examination reveal an accurate diagnosis and evaluate the utility of magnetic resonance imaging (MRI) in lower extremity weakness. We can look to the literature regarding the sensitivity and specificity of the various portions, including the history, physical examination, and imaging. The patient presented with a foot slap, and results of the examination suggest weakness in the tibialis anterior and extensor hallicus longus as well as the gluteus medius. These are all predominantly L5 innervated muscles, but they get their innervation from 2 different peripheral nerves. Vroomen et al [2] evaluated the associations among patient characteristics, physical findings, and lumbosacral nerve root compression on MRI. The study found that the sensitivity of paresis in the tibialis anterior and/or extensor hallicus longus was low, but the specificity was high (0.93). The Cochrane database reviewed [2] the assessment of weakness in the literature and found the sensitivity to range from 0.27-0.62, with the specificity to range from 0.50-0.93, with the highest specificity being the Vroomen study [2]. Thus, we should feel confident that our finding of weakness of the muscles has a fairly strong specificity. In assessing the usefulness of reflexes, we do not find as much information in the literature. The Cochrane database reviewed the loss of Achilles tendon reflex and found the sensitivity to be between 0.14 and 0.61, with the specificity varying from 0.60 to 0.93. This does not help us much because we are looking at a L5 nerve root lesion. The corresponding reflex would be the medial hamstring, which was found to be decreased on the right. In a study by Jensen [4] in 1987, the positive predictive value and negative predictive value of this reflex were assessed in 52 patients. This study
found the positive predictive value of an abnormal medial hamstring to be 85%-89% and the negative predictive value to be between 51% and 61% as a sign of a L45 disk herniation. In this study, they also evaluated the Achilles reflex and found the positive predictive value and negative predictive value to be 67%-84% and 79%-84%, respectively, as a sign of L5S1 disk herniation, which would suggest that, not only is the medial hamstring as good as the Achilles reflex, but it has a fairly good correlation with a positive test in our patient. Provocative maneuvers also are helpful in assessing for a lumbar disk herniation. In our case, the slump sit test was used. Again, in the Cochrane review [3], we found information regarding the usefulness of the straight leg raise test (SLR). Generally, a high sensitivity was found for the examination maneuver but a low specificity when using surgery as the criterion standard and a widely varying specificity, from 0.37 to 1.00, when using imaging as the standard [3]. Although the earlier studies showed the lower specificities, the most recent review, which used surgery as a standard found a specificity of 0.84 [5]. Our patient did not have the SLR evaluated but, instead, had the slump sit test used. To compare the 2 tests, we need to look at a few more recent studies. Ekedahl et al [6] compared SLR and the slump sit test to self-reported disability and found good relationships but did not include imaging. A study that compared SLR and the slump sit test found the slump sit test to have a better sensitivity but a mildly lower specificity when compared with the SLR [7]. Given these data, we now have 3 criteria with good specificity for diagnosing a lumbar radiculopathy from a disk herniation. Does this test give me any information about prognosis or outcomes with respect to treatments? We must first assess the utility of MRI when compared with electrodiagnostic studies. In a study by Nardin et al [8], they found that 40% of the time, only one of these tests is abnormal in patients with radiculopathy. They did not find one more sensitive or specific in the diagnosis of radiculopathy but found that they were complementary because one may be negative in the presence of the lesion. Our patient already has a positive MRI, so our question then becomes whether the MRI is reliable in predicting the outcome of transforaminal epidural steroid injections (TFESI). Recently, Ghahreman and Bogduk [9] published an article that addressed this very point. They evaluated not only the signs and symptoms of the patient but also the MRIs in predicting the outcome of TFESIs. They found that no association of the broad categories of sensory change or neurologic signs was helpful in predicting outcome. What they did find was that a low-grade disk herniation, either paracentral or foraminal, had about a 75% chance of a good response to TFESI. In addition, they found a good association between 2 independent readings of the MRIs [9]. To see if there is any information regarding improved outcomes with electrodiagnostic studies, we must return to
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the literature. A study by Lauder et al [10] evaluated the use of electrodiagnostic studies for diagnosis. They found that the electrodiagnostic studies appeared to be superior when compared with one physical examination component but were less helpful when multiple examination findings were combined to make a diagnosis. In fact, when combining weakness and reflex changes, there was a 96% specificity when compared with electrodiagnostic testing, with a positive predictive value of 80%. When weakness, reflex changes, and sensory changes are included, there was a 100% specificity and positive predictive value. Although we do not have information on sensory changes for our patient, this suggests that the electrodiagnostic study would only be helpful if we could not obtain an accurate sensory examination from our patient. Because there is no mention of communication problems, we should perform the sensory examination before considering an electrodiagnostic study. In a recent study by Fish et al [11], they tried to evaluate the use of electrodiagnostic testing in predicting the outcome of TFESIs. Unfortunately, they did not give us any information on the physical examination findings. In fact, they state that they corroborated the patients’ pain with a pain drawing and history only. They evaluated patients with low back pain and found that those with positive electrodiagnostic testing for radiculopathy did better with TFESIs [11]. Given that this did not include physical examination, the data do not guide us much. Will results of this test change my treatment for this patient? Returning to our patient, we know that there is weakness of the L5 muscles. We also know that we do not have a sensory examination on this patient, which would be my first order of business because it has the chance to solidify our diagnosis. I would explain to him that the injection has both diagnostic and therapeutic effects. To perform electrodiagnostic testing before the injection would not be helpful, given the overwhelming information of the physical examination and MRI. Also the lack of “red flags,” which include weight loss, fever, age ⬎50 years old, and history of cancer [12], he has a high likelihood of having a good outcome with this procedure and to perform another test is not needed at this time, with assuming we get a good sensory examination. If we perform the injection and there are no results, then we should consider an electrodiagnostic study. Other entities that should be on our differential diagnosis list, if he fails the first injection should include, but are not limited to, amyotrophic lateral sclerosis, lumbosacral plexopathy, and sciatic neuropathy.
CONCLUSION So we now know that the physical examination, when it includes a sensory examination is as good as an electrodiag-
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nostic study. We also know that the examination that we currently have is enough to proceed with an epidural. In my opinion, the electrodiagnostic study would be more useful if we had no response to treatment with a TFESI, which might suggest a different disease process. Use of fluoroscopy during TFESI gives a modicum of sensitivity to the injection, such that, if there is no response to the anesthetic, then we should evaluate another disease process. If we perform the electrodiagnostic testing first and found another disease such as peripheral neuropathy, then there is nothing to say that there are not 2 processes that occurred at the same time, and we would consider a trial of the TFESI. Thus, I would perform a lumbar TFESI, and only if I had a failure of treatment with this, would I recommend an electrodiagnostic study.
REFERENCES 1. Dillingham TR. Electrodiagnostic approach to patients with suspected radiculopathy. Phys Med Rehabil Clin N Am 2002;13:567-88. 2. Vroomen PC, de Krom MC, Wilmink JT, Kester AD, Knottnerus JA. Diagnostic value of history and physical examination in patients suspected of lumbosacral nerve root compression. J Neurol Neurosurg Psychiatry 2002;72:630-4. 3. van der Windt DA, Simons E, Riphagen, II, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with lowback pain. Cochrane Database Syst Rev 2010;(2):CD007431. 4. Jensen OH. The medial hamstring reflex in the level-diagnosis of a lumbar disc herniation. Clin Rheumatol 1987;6:570-4. 5. Demircan MN, Colak A, Kutlay M, Kibici K, Topuz K. Cramp finding: Can it be used as a new diagnostic and prognostic factor in lumbar disc surgery? Eur Spine J 2002;11:47-51. 6. Ekedahl KH, Jonsson B, Frobell RB. Validity of the fingertip-to-floor test and straight leg raising test in patients with acute and subacute low back pain: A comparison by sex and radicular pain. Arch Phys Med Rehabil 2010;91:1243-7. 7. Majlesi J, Togay H, Unalan H, Toprak S. The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation. J Clin Rheumatol 2008;14:87-91. 8. Nardin RA, Patel MR, Gudas TF, Rutkove SB, Raynor EM. Electromyography and magnetic resonance imaging in the evaluation of radiculopathy. Muscle Nerve 1999;22:151-5. 9. Ghahreman A, Bogduk N. Predictors of a favorable response to transforaminal injection of steroids in patients with lumbar radicular pain due to disc herniation. Pain Med 2011;12:871-9. 10. Lauder TD, Dillingham TR, Andary M, et al. Effect of history and exam in predicting electrodiagnostic outcome among patients with suspected lumbosacral radiculopathy. Am J Phys Med Rehabil 2000;79:60-68; quiz 75-76. 11. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 12. Chou R, Qaseem A, Snow V, et al. Diagnosis and treatment of low back pain: A joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med 2007;147:478-91.
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Thiru Annaswamy, MD, MA, Rebuts I agree with my esteemed colleague, Robert Irwin, MD, about the 3 questions one should ask before considering the need for further diagnostic testing. Those are precisely the same reasons why I would recommend obtaining an EDX study before considering a lumbar epidural steroid injection (LESI) in A.P.’s case. However, given the same set of facts, Dr Irwin has reached an entirely different conclusion (compared with mine) in his argument. Well, reasonable people can agree to disagree reasonably, and here are my reasons to reasonably disagree with Dr Irwin. In my initial point, I argued that, despite A.P.’s history and physical examination being strongly suggestive of L5 radiculopathy, I would pursue an EDX study due to the diagnostic possibility of common peroneal neuropathy or double crush syndrome. However, Dr Irwin has neither given due consideration to those diagnostic possibilities nor has he explained the lack of documented weakness in ankle invertors. To make and/or improve A.P.’s diagnosis (to paraphrase Dr Irwin), I, therefore, would obtain the EDX study before embarking on an interventional procedure such as an LESI. I do agree with Dr Irwin on one point though. I would perform a sensory examination before doing the EDX study. In regard to Dr Irwin’s second question about whether EDX adds prognostic value in lumbar radiculopathy, he included the same study by Fish et al [1] that I cited in my argument. Yet, he arrives at a different conclusion than mine. I, however, take the conclusions of the study by Fish et al [1], and together with the study by Marchetti et al [2] and our study [3], I believe that there is enough literature support to the prognostic value of EDX in predicting outcomes after LESI. Therefore, armed with localization and pathology information (the presence or absence of axonopathy on electromyography) obtained in the EDX study, I will be better able to advise A.P. on potential outcomes with LESI.
In his third criterion, Dr Irwin questions whether EDX will change his treatment plan for A.P. When there is room for entertaining the possibility of a different diagnosis with the EDX information in hand, I would also submit that there also is room for the possibility that the EDX results might change the treatment plan for A.P. Instead of considering EDX as an option in the event of an unsuccessful LESI (as suggested by Dr Irwin), I would rather do the EDX study before the LESI for all of the reasons outlined above. In addition, I would also not have to deal with a potential nerve root injury that might occur during a transforaminal injection, thereby confounding the results of an EDX study. Lastly, I would like to comment about the undue “pressures” faced by clinicians from insurance companies and patients. George Bernard Shaw famously quipped that “Reasonable people adapt themselves to the world, but unreasonable people attempt to adapt the world to themselves.” I would agree with Dr Irwin that we, as reasonable clinicians, should attempt to adapt ourselves to the changing health care world but only within reason. If, based on the above rationale, you, as a reasonable clinician treating A.P., feel that it is appropriate to do an EDX study before LESI, then I think there is sufficient support for it.
REFERENCES 1. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 2. Marchetti J, Verma-Kurvari S, Patel N, Ohnmeiss DD. Are electrodiagnostic study findings related to a patient’s response to epidural steroid injection? PM R 2010;2:1016-20. 3. Annaswamy TM, Bierner SM, Chouteau W, Elliott AC. Needle electromyography predicts outcome after lumbar epidural steroid injection. Muscle Nerve [Epub ahead of print]. Available at: http://dx.doi.org/ 10.1002/mus.22320. Accessed February 7, 2012.
Robert W. Irwin, MD, Rebuts The decision to perform electrodiagnostic testing (EDX) in this case is clouded by the fact that we did not obtain a full history and physical examination. My colleague makes a few points for performing EDX before doing the epidural injection. I agree that there is literature that EDX can help in situations when there is no clear-cut diagnosis [1], but, in our case, we have a good idea that our diagnosis is correct. Perhaps the best argument for doing the EDX is to diagnose a possible double crush syndrome, but this is no reason to perform the EDX before the initial transforaminal epidural steroid injection (TFESI). The second caveat, that they are complementary, is also true, but, in this case, it is also about the timing of when to perform EDX. First of all, if A.P. were found to have a double crush syndrome, then this would not preclude the use of an epidu-
ral injection to manage symptoms. If one were to give him and injection and there was good symptom relief, then an EDX would not be needed. If there were partial or no relief, then it would be time to proceed with EDX. This allows for us to add to our diagnosis by using the sensitivity and specificity of the epidural itself. In this case, we would recommend a right L5-S1 TFESI. Thus, we could help the patient’s symptoms and enhance our diagnosis without increasing the cost of care unnecessarily. This rationale is based on the fact that the use of TFESIs cannot only be therapeutic but also diagnostic, and there are studies that assessed this [2,3]. One review noted that the sensitivity can range, depending on the study, from 45%-100%, but, in looking at the data better, all but 1 study showed a specificity above 87% [3].
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Another review noted that there is moderate evidence for use of TFESI in the preoperative evaluation of patients with either negative or inconclusive imaging because of a good sensitivity and specificity profile [2]. Diagnostic selective nerve blocks might be considered more specific than TFESIs by the nature of the flow of the injectate to levels above the injected foramen, but they are not more sensitive. Lastly, as we both have discussed in our initial discussion, there are studies that have evaluated the use of EDX in predicting outcomes in TFESIs. Unfortunately, as I mentioned before, the retrospective study by Fish et al [4] did not give any inkling about a physical examination, and we know that a better examination might guide us and is much less expensive to both the patient and the health care system as a whole. I do not have access to the data from my colleague’s upcoming publication, so I cannot comment on it. In this day and age of skyrocketing health care costs, the use of imaging and other testing is only going to get more scrutiny. I feel that, in A.P.’s case, the best course of action would be to
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proceed with the epidural and only if it is not successful, then perform an EDX. Again, it is important to stress that there is no substitute for a thorough history and physical examination, which could clear things up in this case. By proceeding in this manner, we can treat the patient, increase our diagnostic certainty, and possibly save him from having an unnecessary test.
REFERENCES 1. Charles Cho S, Ferrante MA, Levin KH, Harmon RL, So YT. Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: An evidence-based review. Muscle Nerve 2010;42:276-82. 2. Everett CR, Shah RV, Sehgal N, McKenzie-Brown AM. A systematic review of diagnostic utility of selective nerve root blocks. Pain Physician 2005;8:225-33. 3. Rubinstein SM, van Tulder M. A best-evidence review of diagnostic procedures for neck and low-back pain. Best Pract Res Clin Rheumatol 2008;22:471-82. 4. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70.
Electrodiagnostic Testing Before Epidural Steroid Injections CASE SCENARIO A.P. is a 37-year-old man who works loading crates at a hardware store; he developed a right foot slap and lateral lower leg pain after a long day of work. He was referred by his occupational health physician, who suspected lumbar radiculopathy. Initially, the patient worked with a physical therapist, who was able to centralize some of the patient’s symptoms from the patient’s lower leg into the buttock but never was able to fully centralize the symptoms. His foot slap is improving, but he still notices some increased fatigue of his tibialis anterior at long days of work. Because of the persistence of symptoms despite 6 weeks of physical therapy, the patient was referred to you for further assessment, and a magnetic resonance imaging of the lumbar spine was ordered. On examination, you note focal weakness of 4/5 strength in the tibialis anterior and the extensor hallicus longus, and with side-lying hip abduction. You also note a decreased medial hamstring reflex on the affected right side. The slump sit test did provoke symptoms on the right side that is improved with cervical extension. The remainder of the examination is normal. The magnetic resonance imaging reveals a neuroforaminal L5-S1 disk protrusion abutting the right L5 nerve root in the neuroforamen. The patient is interested in having an epidural steroid injection and is inquiring whether he should also have an electrodiagnostic study performed. Arguing that, yes, the patient should also have electrodiagnostic studies performed is Thiru Annaswamy, MD, MA. Arguing that, no, electrodiagnostic studies are not necessary is Robert W. Irwin, MD.
Guest Discussants: Thiru Annaswamy, MD, MA Physical Medicine and Rehabilitation Service, Dallas VA Medical Center, Dallas, TX Disclosure: 8A, AANEM (completed pilot study on EMG in Radiculopathy), AAPMR (completed pilot study on Lumbar Dorsal Ramus Syndrome), 8B, 2010 investigator in completed research study funded by AANEM.
Robert W. Irwin, MD Department of Rehabilitation Medicine, Miller School of Medicine, University of Miami, Miami, FL Disclosure: 8, NIDRR/DOE study SCI complications
Feature Editor: Gary P. Chimes, MD, PhD University of Pittsburgh Medical Center, Pittsburgh, PA. Address correspondence to: G.P.C.; e-mail: [email protected] Disclosure: nothing to disclose
Thiru Annaswamy, MD, MA, Responds I would submit that there are 2 main reasons why I would recommend that the patient described in the case scenario go through an electrodiagnostic evaluation (EDX) before being considered for a lumbar epidural steroid injection (LESI). The first reason is for diagnostic determination, and the second reason is for better prognostication. The main diagnostic question being considered in the case presented here is whether or not the patient, A.P., has a lumbar radiculopathy that affects the right fifth lumbar root (L5R). Charles Cho et al [1] mention in their elegant evidence-based review in the recently published American Association of Neuromuscular and Electrodiagnostic Medicine’s practice topic that, “In those cases with negative imaging findings or atypical clinical presentations, EDX evaluation is especially useful; whereas, in those with abnormal imaging findings, it serves a complementary diagnostic role. A correct diagnosis of lumbosacral radiculopathy is important for implementation of timely and appropriate treatPM&R 1934-1482/12/$36.00 Printed in U.S.A.
ments.” As such, in A.P.’s case, given the information at hand, there is a strong possibility of right L5R. However, there is still a diagnostic possibility of a common peroneal neuropathy (CPN) [2] on the right or the possibility of 2 concurrent diagnoses of L5R and CPN or the possibility of the controversial double-crush syndrome [3], with an initial diagnosis of L5R that subsequently leads to the development of CPN. Given these multiple diagnostic possibilities, it would be extremely useful to perform an EDX evaluation of A.P. at this time before proceeding with any further treatment or management plan. The case to be made here is that EDX is valid, reliable, and useful in differentiating among these diagnostic possibilities and firmly establishing the correct diagnosis. EDX evaluation has long been an extremely valuable tool in the diagnostic armamentarium for clinicians’ management of patients with lumbosacral radiculopathy (LSR) [1]. EDX evaluation for LSR has a considerably higher diagnostic yield than other techniques [4]. The nerve conduction studies © 2012 by the American Academy of Physical Medicine and Rehabilitation Vol. 4, 223-229, March 2012 DOI: 10.1016/j.pmrj.2012.02.006
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portion of the EDX evaluation is noninvasive and standardized, and provides a sensitive measure of the functional status of sensory and motor nerve fibers and, therefore, is valid and reliable in the evaluation of peripheral nerve functioning [5]. The needle electromyographic examination (NEE) part of the EDX has also been demonstrated to be highly objective and reliable in the evaluation of LSR [1,6]. NEE is the only procedure that can document physiological nerve root irritation and is the most sensitive test in detecting a nerve root lesion [7]. An optimal screen has been recommended for the number of muscles to be examined to achieve adequate diagnostic probability for making the diagnosis of LSR [8], which places the level of evidence that supports the use of EDX, especially the NEE portion, in the diagnostic evaluation of patients with LSR at a level II or higher, which is a desirably high level of evidence [9]. The clinical diagnosis of radiculopathy is best made when there is a combination of concurring history and physical examination along with magnetic resonance imaging evidence that supports a corresponding structural lesion causing nerve impingement as well as consensus reached by unanimous independent opinions of more than one physician [10]. In A.P.’s case presented here, there is near concurrence of the presenting history and physical examination, a fairly well concurring structural lesion on magnetic resonance imaging that demonstrates right L5R impingement but only one physician’s opinion that concurs with one physical therapist’s opinion. Although the above combination of diagnostic evidence is reasonably conclusive, it is still possible to firm up the diagnosis further so that some of the not-socongruent elements of the case presentation, as illustrated below, can be better clarified. The features of presentation in A.P.’s case are consistent with the diagnosis of right L5R, which demonstrates gradual and incomplete recovery except for the following 4 atypical features. First, acute development of right foot slap and lateral lower leg pain after a long day of work. This is an atypical acute presenting symptom for radiculopathy because radiculopathy typically presents with back and leg pain in addition to numbness and paresthesias in a dermatomal distribution, and rarely presents initially with weakness (and no other sensory symptoms besides pain) as it has in A.P.’s presentation. The reason for pain and other sensory symptoms such as numbness and paresthesias to be more common than weakness as the initial presenting symptoms in acute radiculopathy is that a lesion large enough to cause motor nerve fiber compromise (causing weakness) is also sufficient enough to cause damage to large afferent fibers that convey proprioception and touch [11]. However, peripheral nerve entrapments, for example, CPN, can present in a variety of ways, including motor predominant or sensory predominant symptoms [12]. Therefore, the absence of numbness in a dermatomal distribution, as in A.P.’s case, although is uncommon in L5R, can be a very characteristic feature in CPN,
due to the peculiar feature of fascicular sparing [2]. Second, in A.P.’s case, the mechanical diagnosis and therapy based physical therapy has had limited success in centralizing A.P.’s pain. Although this does not rule out radiculopathy, it certainly brings into question whether another diagnosis, such as CPN, is in play. Inaccurate diagnosis is one possible explanation of why a highly effective treatment option for acute lumbar radiculopathy, such as mechanical diagnosis and therapy, was not very effective in this case. Third, focal weakness of tibialis anterior and extensor hallucis longus can be features of L5R and CPN [2]. However, the lack of documented weakness in the posterior tibialis (ankle inversion) elicits the possibility of the diagnosis of CPN being in play. It is true that documented weakness of hip abductors points to L5R as the diagnosis, but clinical experience tells me that it is often difficult to assess hip abductor strength adequately due to overlay of pain. Therefore, although the combination of grade 4/5 weakness in the tibialis anterior, extensor hallucis longus, and hip abductors strongly points to L5R, the possibility of an alternate diagnosis, such as CPN, still has to be considered. Fourth, the medial hamstring reflex has been described as being useful in clinically localizing an L5R [13]. However, my clinical experience suggests that it is notoriously difficult to elicit and very unreliable. There are no published reports of the medial hamstring reflex’s inter-rater reliability. However, one can expect it to be lower than the inter-rater reliability of the knee jerk, which is surprisingly poor [14]. Therefore, in my opinion, an unelicitable right medial hamstring reflex in A.P.’s case does not carry much clinical significance. A.P. had a work-related injury. Due to the potential worker’s compensation and medicolegal issues involved in A.P.’s case, it is important to establish the diagnosis clearly without any ambiguity. Both work-related CPN and work-related L5R require equally appropriate management. However, if CPN is revealed as the diagnosis on EDX, an LESI would obviously not be the treatment of choice as the next step in A.P.’s case management. An LESI, subsequently, might still be useful for A.P. because he has a foraminal disk protrusion at L5 that might be amenable to an LESI; however, it merits a lesser priority now if the EDX evaluation supports the diagnosis of CPN. The second main reason why I would recommend that A.P. go through EDX before being considered for an LESI is so that I can better advise him on the expected outcome after LESI. There are 3 recent studies that have examined this particular issue. Fish et al [15] retrospectively studied the predictive value of the NEE portion of EDX for pain and functional outcomes in response to transforaminal epidural steroid injection in LSR. Consecutive subjects had their NEE before transforaminal epidural steroid injection at L4 and/or L5, and had symptomatic pain in only one extremity. They found significantly greater improvement of Oswestry Disability Index scores for NEE-positive radiculopathy (7.11 ⫾ 9.5)
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compared with a negative NEE (3.2 ⫾ 17.4; P ⬍ .05). Pain improvement, however, was not significantly different in the positive NEE group (1.8 ⫾ 1.2) compared with a negative NEE (1.2 ⫾ 1.2; P ⬎ .05). Another recently published study reported a retrospective chart review of patients who had LESI after NEE [16]. No differences were found among NEE positive, negative, and equivocal groups in the response rate to LESIs. The researchers concluded that patients with negative NEE should not be excluded from a trial of LESI. We performed a prospective, multiple regression study and found that abnormal NEE consistent with EDX impression of radiculopathy moderately predicted long-term improvement in pain after LESI [17]. Positive EDX evidence of radiculopathy was predictive of statistically significant better improvement in both pain and functional scores compared with no EDX evidence of radiculopathy, although the patients with normal NEE also tended to favorably respond to LESI [17]. A regression equation, including NEE and other independent predictors, was predictive of pain and functional outcomes [17]. The above research studies clearly support the prognosticating role that EDX has in addition to its well-established role of diagnostic confirmation of lumbar radiculopathy. In A.P.’s case, if his EDX study reveals an abnormal NEE consistent with L5R, then it would be predictive of better outcomes with LESI than if his EDX study was normal. In addition, an EDX study would also provide more details regarding the pathology (axonal versus demyelinating) and severity of the diagnosis, which might also come in handy later. Therefore, armed with the information gleaned from an EDX study, I would be able to more accurately and reliably advise A.P. as to what his diagnosis is and give him betterinformed prognostication information when I obtain his informed consent before giving him an LESI.
REFERENCES 1. Charles Cho S, Ferrante MA, Levin KH, Harmon RL, So YT. Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: An evidence-based review. Muscle Nerve 2010;42:276-82.
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2. Kang PB, Preston DC, Raynor EM. Involvement of superficial peroneal sensory nerve in common peroneal neuropathy. Muscle Nerve 2005; 31:725-9. 3. Schmid A, Coppieters M. The double crush syndrome revisited: A Delphi study to reveal current expert views on mechanisms underlying dual nerve disorders. Man Ther 2011;16:557-62. 4. Dillingham T. Electrodiagnostic medicine II: Clinical evaluation and findings. In: Braddom R, ed. Physical Medicine and Rehabilitation. 3rd ed. Philadelphia, PA: Saunders; 2006, 213. 5. England J, Gronseth G, Franklin G, et al. Distal symmetric polyneuropathy: A definition for clinical research: Report of the American Academy of Neurology, the American Association of Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. Neurology 2005;64:199-207. 6. Chouteau W, Annaswamy T, Bierner S, Elliott A, Figueroa I. Interrater reliability of needle electromyographic findings in lumbar radiculopathy. Am J Phys Med Rehabil 2010;89:561-9. 7. Nardin RA, Patel MR, Gudas TF, Rutkove SB, Raynor EM. Electromyography and magnetic resonance imaging in the evaluation of radiculopathy. Muscle Nerve 1999;22:151-5. 8. Dillingham T, Lauder T, Andary M, et al. Identifying lumbosacral radiculopathies: An optimal electromyographic screen. Am J Phys Med Rehabil 2000;79:496-503. 9. Oxford Centre for Evidence-Based Medicine. Levels of Evidence. Available at http://www.cebm.net; 2009. Accessed December 21, 2011. 10. Haig AJ, Tong HC, Yamakawa KS, et al. The sensitivity and specificity of electrodiagnostic testing for the clinical syndrome of lumbar spinal stenosis. Spine (Phila Pa 1976) 2005;30:2667-76. 11. Radiculopathies. In: Dumitru D. Electrodiagnostic Medicine. Philadelphia, PA: Hanley and Belfus; 1995, 539. 12. Sourkes M, Stewart J. Common peroneal neuropathy: A study of selective motor and sensory involvement. Neurology 1991;41:102933. 13. Jensen OH. The medial hamstring reflex in the level-diagnosis of a lumbar disc herniation. Clin Rheumatol 1987;6:570-4. 14. Stam J, van Crevel H. Reliability of the clinical and electromyographic examination of tendon reflexes. J Neurol 1990;237:427-31. 15. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 16. Marchetti J, Verma-Kurvari S, Patel N, Ohnmeiss DD. Are electrodiagnostic study findings related to a patient’s response to epidural steroid injection? PM R 2010;2:1016-20. 17. Annaswamy TM, Bierner SM, Chouteau W, Elliott AC. Needle electromyography predicts outcome after lumbar epidural steroid injection. Muscle Nerve 2012;45:346-55.
Robert W. Irwin, MD, Responds In our current health care system, the physician must balance the care of the patient with the ballooning cost of delivering this health care. Unlike in the past, when the physician may have ordered a whole battery of tests, some of which were not needed, today’s physician must balance the cost of that care with the benefits. In truth, often enough, the physician will order a test only to have the insurance company deny it as they try to cut costs. To add to these pressures, with the advent of direct-to-consumer advertisement and the growth of information accessibility on the Internet, patients often request certain tests and treatments that they believe they need, without fully un-
derstanding the pathophysiology of the health issue. Because of these pressures, now more than ever, the treating physician needs to make judicious use of the testing at hand. Dillingham [1] suggests that the utility of electrodiagnostic studies is to exclude other diagnoses that mimic radiculopathy. Electrodiagnostic studies may also suggest severity or extent of the disorder beyond clinical symptoms as well as solidifying the diagnosis when there are mild or nonspecific findings on imaging studies. He also notes that a positive electrodiagnostic study may be helpful in outcome prediction in surgical cases [1].
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In this case, the patient is interested in having an epidural injection. The question is whether there is any advantage to have an electrodiagnostic study before the injection. When assessing whether further testing should be performed, it behooves the physician to have goals in minds for ordering such tests. These should include the following: 1. How much does this test help in making and/or improving the diagnosis? 2. Does this test give me any information about prognosis or outcomes with respect to treatments? 3. Will results of this test change my treatment for this patient? How much does this test help in making the diagnosis? The purpose of obtaining a thorough history and physical examination is to better care for the patient and of testing is to augment this information. When opting to order additional testing, the physician should assess the need to enhance the information already gathered. Before deciding if an electrodiagnostic study should be performed, we should assess whether we believe that the workup performed so far is adequate. In this case, we should assess to what extent our history and physical examination reveal an accurate diagnosis and evaluate the utility of magnetic resonance imaging (MRI) in lower extremity weakness. We can look to the literature regarding the sensitivity and specificity of the various portions, including the history, physical examination, and imaging. The patient presented with a foot slap, and results of the examination suggest weakness in the tibialis anterior and extensor hallicus longus as well as the gluteus medius. These are all predominantly L5 innervated muscles, but they get their innervation from 2 different peripheral nerves. Vroomen et al [2] evaluated the associations among patient characteristics, physical findings, and lumbosacral nerve root compression on MRI. The study found that the sensitivity of paresis in the tibialis anterior and/or extensor hallicus longus was low, but the specificity was high (0.93). The Cochrane database reviewed [2] the assessment of weakness in the literature and found the sensitivity to range from 0.27-0.62, with the specificity to range from 0.50-0.93, with the highest specificity being the Vroomen study [2]. Thus, we should feel confident that our finding of weakness of the muscles has a fairly strong specificity. In assessing the usefulness of reflexes, we do not find as much information in the literature. The Cochrane database reviewed the loss of Achilles tendon reflex and found the sensitivity to be between 0.14 and 0.61, with the specificity varying from 0.60 to 0.93. This does not help us much because we are looking at a L5 nerve root lesion. The corresponding reflex would be the medial hamstring, which was found to be decreased on the right. In a study by Jensen [4] in 1987, the positive predictive value and negative predictive value of this reflex were assessed in 52 patients. This study
found the positive predictive value of an abnormal medial hamstring to be 85%-89% and the negative predictive value to be between 51% and 61% as a sign of a L45 disk herniation. In this study, they also evaluated the Achilles reflex and found the positive predictive value and negative predictive value to be 67%-84% and 79%-84%, respectively, as a sign of L5S1 disk herniation, which would suggest that, not only is the medial hamstring as good as the Achilles reflex, but it has a fairly good correlation with a positive test in our patient. Provocative maneuvers also are helpful in assessing for a lumbar disk herniation. In our case, the slump sit test was used. Again, in the Cochrane review [3], we found information regarding the usefulness of the straight leg raise test (SLR). Generally, a high sensitivity was found for the examination maneuver but a low specificity when using surgery as the criterion standard and a widely varying specificity, from 0.37 to 1.00, when using imaging as the standard [3]. Although the earlier studies showed the lower specificities, the most recent review, which used surgery as a standard found a specificity of 0.84 [5]. Our patient did not have the SLR evaluated but, instead, had the slump sit test used. To compare the 2 tests, we need to look at a few more recent studies. Ekedahl et al [6] compared SLR and the slump sit test to self-reported disability and found good relationships but did not include imaging. A study that compared SLR and the slump sit test found the slump sit test to have a better sensitivity but a mildly lower specificity when compared with the SLR [7]. Given these data, we now have 3 criteria with good specificity for diagnosing a lumbar radiculopathy from a disk herniation. Does this test give me any information about prognosis or outcomes with respect to treatments? We must first assess the utility of MRI when compared with electrodiagnostic studies. In a study by Nardin et al [8], they found that 40% of the time, only one of these tests is abnormal in patients with radiculopathy. They did not find one more sensitive or specific in the diagnosis of radiculopathy but found that they were complementary because one may be negative in the presence of the lesion. Our patient already has a positive MRI, so our question then becomes whether the MRI is reliable in predicting the outcome of transforaminal epidural steroid injections (TFESI). Recently, Ghahreman and Bogduk [9] published an article that addressed this very point. They evaluated not only the signs and symptoms of the patient but also the MRIs in predicting the outcome of TFESIs. They found that no association of the broad categories of sensory change or neurologic signs was helpful in predicting outcome. What they did find was that a low-grade disk herniation, either paracentral or foraminal, had about a 75% chance of a good response to TFESI. In addition, they found a good association between 2 independent readings of the MRIs [9]. To see if there is any information regarding improved outcomes with electrodiagnostic studies, we must return to
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the literature. A study by Lauder et al [10] evaluated the use of electrodiagnostic studies for diagnosis. They found that the electrodiagnostic studies appeared to be superior when compared with one physical examination component but were less helpful when multiple examination findings were combined to make a diagnosis. In fact, when combining weakness and reflex changes, there was a 96% specificity when compared with electrodiagnostic testing, with a positive predictive value of 80%. When weakness, reflex changes, and sensory changes are included, there was a 100% specificity and positive predictive value. Although we do not have information on sensory changes for our patient, this suggests that the electrodiagnostic study would only be helpful if we could not obtain an accurate sensory examination from our patient. Because there is no mention of communication problems, we should perform the sensory examination before considering an electrodiagnostic study. In a recent study by Fish et al [11], they tried to evaluate the use of electrodiagnostic testing in predicting the outcome of TFESIs. Unfortunately, they did not give us any information on the physical examination findings. In fact, they state that they corroborated the patients’ pain with a pain drawing and history only. They evaluated patients with low back pain and found that those with positive electrodiagnostic testing for radiculopathy did better with TFESIs [11]. Given that this did not include physical examination, the data do not guide us much. Will results of this test change my treatment for this patient? Returning to our patient, we know that there is weakness of the L5 muscles. We also know that we do not have a sensory examination on this patient, which would be my first order of business because it has the chance to solidify our diagnosis. I would explain to him that the injection has both diagnostic and therapeutic effects. To perform electrodiagnostic testing before the injection would not be helpful, given the overwhelming information of the physical examination and MRI. Also the lack of “red flags,” which include weight loss, fever, age ⬎50 years old, and history of cancer [12], he has a high likelihood of having a good outcome with this procedure and to perform another test is not needed at this time, with assuming we get a good sensory examination. If we perform the injection and there are no results, then we should consider an electrodiagnostic study. Other entities that should be on our differential diagnosis list, if he fails the first injection should include, but are not limited to, amyotrophic lateral sclerosis, lumbosacral plexopathy, and sciatic neuropathy.
CONCLUSION So we now know that the physical examination, when it includes a sensory examination is as good as an electrodiag-
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nostic study. We also know that the examination that we currently have is enough to proceed with an epidural. In my opinion, the electrodiagnostic study would be more useful if we had no response to treatment with a TFESI, which might suggest a different disease process. Use of fluoroscopy during TFESI gives a modicum of sensitivity to the injection, such that, if there is no response to the anesthetic, then we should evaluate another disease process. If we perform the electrodiagnostic testing first and found another disease such as peripheral neuropathy, then there is nothing to say that there are not 2 processes that occurred at the same time, and we would consider a trial of the TFESI. Thus, I would perform a lumbar TFESI, and only if I had a failure of treatment with this, would I recommend an electrodiagnostic study.
REFERENCES 1. Dillingham TR. Electrodiagnostic approach to patients with suspected radiculopathy. Phys Med Rehabil Clin N Am 2002;13:567-88. 2. Vroomen PC, de Krom MC, Wilmink JT, Kester AD, Knottnerus JA. Diagnostic value of history and physical examination in patients suspected of lumbosacral nerve root compression. J Neurol Neurosurg Psychiatry 2002;72:630-4. 3. van der Windt DA, Simons E, Riphagen, II, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with lowback pain. Cochrane Database Syst Rev 2010;(2):CD007431. 4. Jensen OH. The medial hamstring reflex in the level-diagnosis of a lumbar disc herniation. Clin Rheumatol 1987;6:570-4. 5. Demircan MN, Colak A, Kutlay M, Kibici K, Topuz K. Cramp finding: Can it be used as a new diagnostic and prognostic factor in lumbar disc surgery? Eur Spine J 2002;11:47-51. 6. Ekedahl KH, Jonsson B, Frobell RB. Validity of the fingertip-to-floor test and straight leg raising test in patients with acute and subacute low back pain: A comparison by sex and radicular pain. Arch Phys Med Rehabil 2010;91:1243-7. 7. Majlesi J, Togay H, Unalan H, Toprak S. The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation. J Clin Rheumatol 2008;14:87-91. 8. Nardin RA, Patel MR, Gudas TF, Rutkove SB, Raynor EM. Electromyography and magnetic resonance imaging in the evaluation of radiculopathy. Muscle Nerve 1999;22:151-5. 9. Ghahreman A, Bogduk N. Predictors of a favorable response to transforaminal injection of steroids in patients with lumbar radicular pain due to disc herniation. Pain Med 2011;12:871-9. 10. Lauder TD, Dillingham TR, Andary M, et al. Effect of history and exam in predicting electrodiagnostic outcome among patients with suspected lumbosacral radiculopathy. Am J Phys Med Rehabil 2000;79:60-68; quiz 75-76. 11. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 12. Chou R, Qaseem A, Snow V, et al. Diagnosis and treatment of low back pain: A joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med 2007;147:478-91.
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Thiru Annaswamy, MD, MA, Rebuts I agree with my esteemed colleague, Robert Irwin, MD, about the 3 questions one should ask before considering the need for further diagnostic testing. Those are precisely the same reasons why I would recommend obtaining an EDX study before considering a lumbar epidural steroid injection (LESI) in A.P.’s case. However, given the same set of facts, Dr Irwin has reached an entirely different conclusion (compared with mine) in his argument. Well, reasonable people can agree to disagree reasonably, and here are my reasons to reasonably disagree with Dr Irwin. In my initial point, I argued that, despite A.P.’s history and physical examination being strongly suggestive of L5 radiculopathy, I would pursue an EDX study due to the diagnostic possibility of common peroneal neuropathy or double crush syndrome. However, Dr Irwin has neither given due consideration to those diagnostic possibilities nor has he explained the lack of documented weakness in ankle invertors. To make and/or improve A.P.’s diagnosis (to paraphrase Dr Irwin), I, therefore, would obtain the EDX study before embarking on an interventional procedure such as an LESI. I do agree with Dr Irwin on one point though. I would perform a sensory examination before doing the EDX study. In regard to Dr Irwin’s second question about whether EDX adds prognostic value in lumbar radiculopathy, he included the same study by Fish et al [1] that I cited in my argument. Yet, he arrives at a different conclusion than mine. I, however, take the conclusions of the study by Fish et al [1], and together with the study by Marchetti et al [2] and our study [3], I believe that there is enough literature support to the prognostic value of EDX in predicting outcomes after LESI. Therefore, armed with localization and pathology information (the presence or absence of axonopathy on electromyography) obtained in the EDX study, I will be better able to advise A.P. on potential outcomes with LESI.
In his third criterion, Dr Irwin questions whether EDX will change his treatment plan for A.P. When there is room for entertaining the possibility of a different diagnosis with the EDX information in hand, I would also submit that there also is room for the possibility that the EDX results might change the treatment plan for A.P. Instead of considering EDX as an option in the event of an unsuccessful LESI (as suggested by Dr Irwin), I would rather do the EDX study before the LESI for all of the reasons outlined above. In addition, I would also not have to deal with a potential nerve root injury that might occur during a transforaminal injection, thereby confounding the results of an EDX study. Lastly, I would like to comment about the undue “pressures” faced by clinicians from insurance companies and patients. George Bernard Shaw famously quipped that “Reasonable people adapt themselves to the world, but unreasonable people attempt to adapt the world to themselves.” I would agree with Dr Irwin that we, as reasonable clinicians, should attempt to adapt ourselves to the changing health care world but only within reason. If, based on the above rationale, you, as a reasonable clinician treating A.P., feel that it is appropriate to do an EDX study before LESI, then I think there is sufficient support for it.
REFERENCES 1. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70. 2. Marchetti J, Verma-Kurvari S, Patel N, Ohnmeiss DD. Are electrodiagnostic study findings related to a patient’s response to epidural steroid injection? PM R 2010;2:1016-20. 3. Annaswamy TM, Bierner SM, Chouteau W, Elliott AC. Needle electromyography predicts outcome after lumbar epidural steroid injection. Muscle Nerve [Epub ahead of print]. Available at: http://dx.doi.org/ 10.1002/mus.22320. Accessed February 7, 2012.
Robert W. Irwin, MD, Rebuts The decision to perform electrodiagnostic testing (EDX) in this case is clouded by the fact that we did not obtain a full history and physical examination. My colleague makes a few points for performing EDX before doing the epidural injection. I agree that there is literature that EDX can help in situations when there is no clear-cut diagnosis [1], but, in our case, we have a good idea that our diagnosis is correct. Perhaps the best argument for doing the EDX is to diagnose a possible double crush syndrome, but this is no reason to perform the EDX before the initial transforaminal epidural steroid injection (TFESI). The second caveat, that they are complementary, is also true, but, in this case, it is also about the timing of when to perform EDX. First of all, if A.P. were found to have a double crush syndrome, then this would not preclude the use of an epidu-
ral injection to manage symptoms. If one were to give him and injection and there was good symptom relief, then an EDX would not be needed. If there were partial or no relief, then it would be time to proceed with EDX. This allows for us to add to our diagnosis by using the sensitivity and specificity of the epidural itself. In this case, we would recommend a right L5-S1 TFESI. Thus, we could help the patient’s symptoms and enhance our diagnosis without increasing the cost of care unnecessarily. This rationale is based on the fact that the use of TFESIs cannot only be therapeutic but also diagnostic, and there are studies that assessed this [2,3]. One review noted that the sensitivity can range, depending on the study, from 45%-100%, but, in looking at the data better, all but 1 study showed a specificity above 87% [3].
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Another review noted that there is moderate evidence for use of TFESI in the preoperative evaluation of patients with either negative or inconclusive imaging because of a good sensitivity and specificity profile [2]. Diagnostic selective nerve blocks might be considered more specific than TFESIs by the nature of the flow of the injectate to levels above the injected foramen, but they are not more sensitive. Lastly, as we both have discussed in our initial discussion, there are studies that have evaluated the use of EDX in predicting outcomes in TFESIs. Unfortunately, as I mentioned before, the retrospective study by Fish et al [4] did not give any inkling about a physical examination, and we know that a better examination might guide us and is much less expensive to both the patient and the health care system as a whole. I do not have access to the data from my colleague’s upcoming publication, so I cannot comment on it. In this day and age of skyrocketing health care costs, the use of imaging and other testing is only going to get more scrutiny. I feel that, in A.P.’s case, the best course of action would be to
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proceed with the epidural and only if it is not successful, then perform an EDX. Again, it is important to stress that there is no substitute for a thorough history and physical examination, which could clear things up in this case. By proceeding in this manner, we can treat the patient, increase our diagnostic certainty, and possibly save him from having an unnecessary test.
REFERENCES 1. Charles Cho S, Ferrante MA, Levin KH, Harmon RL, So YT. Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: An evidence-based review. Muscle Nerve 2010;42:276-82. 2. Everett CR, Shah RV, Sehgal N, McKenzie-Brown AM. A systematic review of diagnostic utility of selective nerve root blocks. Pain Physician 2005;8:225-33. 3. Rubinstein SM, van Tulder M. A best-evidence review of diagnostic procedures for neck and low-back pain. Best Pract Res Clin Rheumatol 2008;22:471-82. 4. Fish DE, Shirazi EP, Pham Q. The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy. J Pain 2008;9:64-70.