The use of electromyography to predict functional outcome following transforaminal epidural spinal injections for lumbar radiculopathy

Serial electrodiagnostic testing: Utility and indications in adult neurological disorders

Although existing guidelines address electrodiagnostic (EDX) testing in identifying neuromuscular conditions, guidance regarding the uses and limitations of serial (or repeat) EDX testing is limited. By assessing neurophysiological change longitudinally across time, serial electrodiagnosis can clarify a diagnosis and potentially provide valuable prognostic information. This monograph presents four broad indications for serial electrodiagnosis in adult peripheral neurological disorders. First, where clinical change has raised suspicion for a new or ongoing lesion, EDX reassessment for spatial spread of abnormality, involvement of previously normal muscle or nerve, and/or evolving pathophysiology can clarify a diagnosis. Second, where diagnosis of a progressive neuromuscular condition is uncertain, electrophysiological data from a second time point can confirm or refute suspicion. Third, to establish prognosis after a static nerve injury, a repeat study can assess the presence and extent of reinnervation. Finally, faced with a limited initial study (as when complicated by patient or environmental factors), a repeat EDX study can supplement missing or limited data to provide needed clarity. Repeat EDX studies carry certain limitations, however, such as with prognostication in the setting of remote or chronic lesions, sensory predominant fascicular injury, or mild axonal injury. Nevertheless, serial electrodiagnosis remains a valuable and underused tool in the diagnostic and prognostic evaluation of neuromuscular conditions.

Nerve root anomaly as a cause of unexpected outcomes of epidural steroid injections in lumbar radiculopathy: A case report

BACKGROUND

Spinal nerve root anomaly is a rare feature that can result in unexpected outcomes in epidural steroid injections or surgical procedures. Preoperative diagnostic tools for root anomalies are limited, as they are usually found intraoperatively.

OBJECTIVE

This case report aims to propose an effective diagnostic process for nerve root anomalies by introducing clinical manifestations, electrodiagnostic findings, and sophisticated imaging techniques such as coronal view magnetic resonance imaging (MRI) of the lumbosacral spine.

CASE DESCRIPTION

A 43-year-old female complained of low back pain with radicular pain to the lower extremities. Based on physical examination, electrodiagnosis, and imaging studies, right L5 radiculopathy was diagnosed. Repetitive image-guided epidural steroid injections presented unsuccessful outcomes. She was then referred to a neurosurgeon for surgical decompression, which resulted in significant improvement in her radicular pain. A nerve root anomaly was found intraoperatively, and the coronal images of postoperative MRI depicted the conjoined nerve root of the lumbar spine.

CONCLUSION

When proper image-guided spinal interventions for discogenic radicular pain are not effective, a clinician should be advised to consider the possibility of anatomical variation, including nerve root anomalies. Early diagnosis of nerve root anomalies by utilizing multiple diagnostic tools, especially coronal MRI, can aid in preoperative diagnosis and proper clinical decisions for symptom management.

Electromyography and Therapeutic Response to Lumbosacral Epidural Steroid Injections: A Systematic Review

The association between electromyography (EMG)-confirmed lumbosacral (LS) radiculopathy and pain outcomes following epidural steroid injection (ESI) has not been systematically summarized. The primary objective of this systematic review was to summarize the effects of EMG-confirmed LS radiculopathy on pain intensity following ESI. A secondary objective was to summarize the effects of EMG-confirmed LS radiculopathy on physical functioning following ESI. An a priori protocol was registered and a database search conducted by a reference librarian from January 2000 through December 2020. The search was date-limited to ensure the results of the systematic review represented contemporary clinical practice. Study-inclusion criteria included randomized trials, prospective and retrospective studies, cross-sectional studies, case series, and case reports, age ≥18 years, and use of EMG as a prognostic tool prior to an ESI. Two independent reviewers screened all titles, abstracts, and full texts. Data were extracted using a templated electronic database. The risk of bias was assessed using the Risk of Bias in Nonrandomized Studies of Interventions tool and certainty in evidence assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach. Due to clinical heterogeneity in study characteristics, a meta-analysis was not performed. A total of 454 studies were screened, and eight nonrandomized studies met the inclusion criteria. Five studies had a moderate risk of bias, two serious risks, and one a critical risk. The key findings included four of eight nonrandomized studies reporting a significant association between EMG-confirmed radiculopathy and ESI response and four of eight nonrandomized studies reporting no significant association. Important sources of bias limited interpretation of individual study findings, and multiple sources of clinical heterogeneity limited between-study comparisons. The findings of this systematic review demonstrate that associations existed between EMG-confirmed LS radiculopathy and pain outcomes after ESI in some, but not all studies. These results should be carefully interpreted with full understanding of the risk of bias and very low certainty in evidence that characterize the nonrandomized studies comprising this systematic review.

Role of paraspinal mapping before transforaminal epidural injections for lumbar radiculopathy

Objectives

This study aims to investigate whether electromyography (EMG) including paraspinal mapping (PM) and specific clinical findings before the injection have a predictive role on the results in patients undergoing unilateral transforaminal epidural steroid injection (TFESI).

Patients and methods

In this prospective study, a total of 46 patients (19 males, 17 females; mean age: 44.0±10.8 years; range, 23 to 60 years) with unilateral L5 root compression confirmed by physical examination, EMG and lumbar MRI between March 2013 and January 2014 were included. The patients underwent L5 TFESI. After the injection, they were examined at 1 h, three weeks, and three months.

Results

The clinical findings and presence of acute involvement on EMG were not predictive for TFESI results; however, the patients with lower scores for the L5 segment in PM benefited more from the injection, compared to patients with higher scores for the L5 segment in PM.

Conclusion

In patients with very clearly defined L5 radiculopathy, PM EMG can give us an idea about the effectiveness of L5 TFESI.

The Outcome of Pulsed Radiofrequency Treatment According to Electodiagnosis in Patients with Intractable Lumbosacral Radicular Pain

BACKGROUND

Radicular pain is related to lesions that either directly compromise the dorsal root ganglion (DRG) or indirectly compromise the spinal nerve and its roots by causing ischemia or inflammation of the axons.

OBJECTIVE

Our study aimed to assess the outcomes of pulsed readiofrequency treatment (PRF) according to electrodiagnosis results in patients with chronic intractable lumbosacral radicular pain.

METHODS

A total of 82 failed back surgery syndrome (FBSS) patients were included in this study. All of them underwent electromyography/nerve conduction studies before pulsed radiofrequency (PRF) treatment at the DRG, and they were classified according to the electrodiagnostic results as: group 1, no definite finding (normal); group 2, radiculopathy; and group 3, neuropathy. Pain intensity was assessed according to a numeric rating scale score and the Oswestry Disability Index (ODI) before treatment and at one, three, six, and 12 months after treatment, and successful treatment was defined as a pain score reduction of ≥50% at 12 months, as compared with the pretreatment score.

RESULTS

Pretreatment electrodiagnosis identified 28 patients with no definite findings, 31 patients with radiculopathy, and 23 patients with neuropathy. The patients with neuropathy had less pain relief after treatment than those with no definite findings and those with radiculopathy. The prevalence of pain reduction of at least 50% was lower in the neuropathy group than in the other groups. There was no statistically significant difference in ODI between group.

CONCLUSION

Outcomes after PRF at the DRG did not show strong differences according to electrodiagnostic findings in FBSS patients with chronic intractable lumbosacral radicular pain.

Evaluation of persons with suspected lumbosacral and cervical radiculopathy: Electrodiagnostic assessment and implications for treatment and outcomes (Part II)

The electrodiagnostic (EDX) examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and complements imaging of the spine. In this second of a two-part review, the implications of electrodiagnostic findings for diagnosis and clinical management of persons with radiculopathy are reviewed. An EMG confirmed lumbosacral radiculopathy is associated with better clinical outcomes for persons undergoing aggressive conservative management. A positive EMG test portends a better clinical response to epidural corticosteroid injections. If a person undergoes spine surgery, a positive pre-operative EMG for radiculopathy is also associated with better outcomes.

Ultrasound-guided caudal epidural steroid injection in chronic radicular low back pain: short-term electrophysiologic benefits

OBJECTIVE

To assess the short-term efficacy of ultrasound-guided caudal epidural steroid injections (ESIs) in improving pain, and nerve function as measured by electrophysiological testing in chronic radicular low back pain.

METHODS

Patients diagnosed with chronic radicular low back pain were randomized into one of two groups. The injection group (n = 20) underwent a single ultrasound-guided Caudal ESI of 1 ml of 40 mg ml-1 Triamcinolone Acetonide (Kenacort-A), with local anesthetic. The control group (n = 20) underwent a 12-session physiotherapy program. Both groups were evaluated before and 2 weeks after the intervention using visual analog scale for pain and electrophysiological testing comprising peroneal and tibial terminal motor latencies and F-response latencies and chronodispersion.

RESULTS

Both groups showed significant pain reduction on the visual analog scale after the intervention. The injection group showed a significant reduction in F wave chronodispersion post-treatment (<0.01). In the control group, there were no significant differences in F wave parameters pre- and post-treatment (p > 0.05).

CONCLUSION

Caudal ESIs were shown to provide short-term improvement of nerve function as evident by improvement in the electrophysiological parameters sensitive to radiculopathy. It was found to be superior to standard physical therapy in this regard.

ADVANCES IN KNOWLEDGE

This work shows a novel electrophysiologic evidence of the short-term efficacy ultrasound-guided caudal ESI.

Predicting Response to Epidural Steroid Injections for Lumbar Spinal Stenosis with Biomarkers and Electromyography

BACKGROUND

Epidural steroid injections (ESIs) may be beneficial for lumbar spinal stenosis (LSS) symptoms. Past studies found interferon-gamma, fibronectin-aggrecan complex, and electromyography (EMG) to predict patients' response to ESIs for other spinal pathologies, but no similar studies have been done for LSS.

OBJECTIVE

To explore the ability of biomarkers and EMG to help predict outcome after ESI in LSS.

DESIGN

Prospective observational cohort.

SETTING

The physical medicine & rehabilitation spine clinic at a tertiary care center.

PARTICIPANTS

Eleven patients with LSS were recruited from the spine clinic at a Veterans Affairs Medical Center.

INTERVENTIONS

Participants underwent one interlaminar ESI. Before ESI, the following data were collected: pain intensity on visual analog scale (VAS), disability via the Pain Disability Questionnaire (PDQ) and LSS symptoms via the Swiss Spinal Stenosis Questionnaire (SSSQ), serum high-sensitivity C-reactive protein level, standard diagnostic EMG, assay of epidural lavasate (epidural saline lavage performed immediately prior to ESI) and serum cytokine biomarkers indicative of inflammation.

OUTCOME MEASURES

Leg pain intensity (VAS), disability (PDQ), LSS symptoms (SSSQ) and satisfaction (SSSQ satisfaction subscale) were assessed at 1 and 2 months following ESI. Pearson correlational coefficients were calculated between independent variables and outcome measures.

RESULTS

Serum monocyte chemoattractant protein-1 (MCP-1) level positively correlated with improvement on 2-month satisfaction. Abnormal EMG finding of radiculopathy positively correlated with improvement in PDQ score at 1 month. Epidural cytokine levels were not detectable in most samples, except for scattered marginally elevated levels in a few cytokines such as MCP-1, RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted) and interleukin-1b.

CONCLUSIONS

This exploratory pilot study revealed that some biomarkers and EMG findings indicative of inflammation and nerve root injury may be predictive of improvement following ESI in patients with LSS. The results of this study will be used to inform a fully powered study to further evaluate these relationships in LSS patients.

Factors Predicting Favorable Short-Term Response to Transforaminal Epidural Steroid Injections for Lumbosacral Radiculopathy

Background and Objectives: The purpose of this retrospective study was to identify predictors of short-term outcomes associated with a lumbosacral transforaminal epidural steroid injection (TFESI). Materials and Methods: The medical records of 218 patients, who were diagnosed with lumbosacral radiculopathy and treated with a TFESI, were reviewed in this retrospective study. A mixture of corticosteroid, lidocaine, and hyaluronidase was injected during TFESI. Patients with >50% pain relief on the numerical rating scale compared with the initial visit constituted the good responder group. Demographic, clinical, MRI, and electrodiagnostic data were collected to assess the predictive factors for short-term outcomes of the TFESI. Results: A multivariate logistic regression analysis demonstrated that a shorter duration of symptoms and a positive sharp wave (PSW)/fibrillation (Fib) observed in electrodiagnostic study (EDx) increased the odds of significant improvement 2–4 weeks after the TFESI. Conclusions: Shorter duration of symptoms and PSW/Fib on EDx were predictors of favorable short-term response to TFESI.

The Value of Electrodiagnostic Studies in Predicting Treatment Outcomes for Patients with Spine Pathologies

The utility of electrodiagnostic testing for spine pathologies varies based on the underlying suspected pathology. This article reviews the data on electrodiagnostic testing for common spine pathologies, with a specific focus on the prognostic data with regard to treatment outcomes. This information is placed into context of diagnostic confidence, which is derived from the combination of disease prevalence and the sensitivity and specificity of a test.

Electromyographic Findings After Epidural Steroid Injections in Patients with Radicular Low Back Pain: A Prospective Open-Label Study

Epidural steroid injections (ESIs) are commonly used in the management of chronic lower back and leg pain. The aim of this study was to investigate the short- and long-term electromyographic and clinical outcome of patients with chronic radicular pain after ESIs. This prospective, open-label study, included patients with chronic radicular pain due to disc herniation or spinal stenosis, who underwent interlaminar, fluoroscopy-guided ESIs. Patients were assessed before ESIs, as well as after 6 and 12 months, clinically (VAS 0-10, BPI, DN4, Rolland Morris, DASS, STAI) and electromyographically for the improvement of spontaneous activity (SA) and of motor unit recruitment/interference pattern (IP/MUR). A total of 39 patients were studied, 20 (51.3%) who had a significant improvement in VAS, RM, DN4 and BPI were revealed, mainly during the first 6 months (P < 0.05). Statistically significant improvement was revealed in MUR/SA for almost all nerve roots studied. Patients with disc herniation showed a greater improvement in mean difference of MUR/SA (P < 0.05) (with a prognostic value of radicular LBP versus spinal stenosis in short- [VAS P = 0.042] and long-term improvement of pain [VAS P = 0.009]. The independent variables “MUR” and “SA” had a significant prognostic value for improvement of pain (VAS: R² = 0.287, P = 0.032 and VAS: R² = 0.277, P = 0.036 respectively). Electromyographic and clinical findings indicated a benefit from epidural steroid injections. Patients with disc herniation exhibited a better outcome, especially during the first 6 months post-treatment.

Three week results of transforaminal epidural steroid injection in patients with chronic unilateral low back related leg pain: The relation to MRI findings and clinical features

BACKGROUND

Transforaminal epidural steroid injection (TESI) is a frequently used intervention for lumbar radicular pain.

OBJECTIVE

To evaluate the value of MRI findings, neurologic assessment and the Slump test (neurodynamic test) as predictors of treatment response to TESI.

METHOD

One hundred subjects (mean age 58 [SD13], 54% females) were included in this trial. The sample was stratified by location of disc herniaton, grade of nerve root compression, clinically assessed neurologic deficit and positive Slump test.Treatment response was primarily evaluated by Visual Analogue Scale for leg pain after three weeks. Predictive value for each stratum was analyzed using logistic regression after the sample was dichotomized into definite treatment response (≥ 50% reduction of pain) and negative response (≤ 0% reduction) to TESI (the 1-49% reduction group was excluded).

RESULTS

The overall definite treatment response rate was 27%. The Slump test was the only predictor of the response to TESI (p= 0.031). The definite treatment response rates for subjects with positive and negative Slump test were 33% and 15%, respectively.

CONCLUSION

In patients with chronic low back related leg pain, MRI findings and neurologic assessment results failed to predict treatment response, whereas a positive Slump test predicted the best 3-week response to TESI.

The prognostic value of electrodiagnostic testing in patients with sciatica receiving physical therapy

PURPOSE

To investigate the prognostic value of electrodiagnostic testing in patients with sciatica receiving physical therapy.

METHODS

Electrodiagnostic testing was performed on 38 patients with sciatica participating in a randomized trial comparing different physical therapy interventions. Patients were grouped and analyzed according to the presence or absence of radiculopathy based on electrodiagnostic testing. Longitudinal data analysis was conducted using multilevel growth modeling with ten waves of data collected from baseline through the treatment and post-treatment periods up to 6 months. The primary outcome measure was changes in low back pain-related disability assessed using the Roland and Morris disability questionnaire (RMDQ).

RESULTS

Patients with radiculopathy (n = 19) had statistically significant and clinically meaningful improvements in RMDQ scores at every post-treatment follow-up occasion regardless of treatment received. The final multilevel growth model revealed improvements in RMDQ scores in patients with radiculopathy at the 6-week (-8.1, 95 % CI -12.6 to -2.6; P = 0.006) and 6-month (-4.1, 95 % CI -7.4 to -0.7; P = 0.020) follow-up occasions compared to patients without radiculopathy. Treatment group was not a significant predictive factor at any follow-up occasion. An interaction between electrodiagnostic status and time revealed faster weekly improvements in RMDQ scores in patients with radiculopathy at the 6-week (-0.72, 95 % CI -1.4 to -0.04; P = 0.040) through the 16-week (-0.30, 95 % CI, -0.57 to -0.04; P = 0.028) follow-up occasions compared to patients without radiculopathy.

CONCLUSIONS

The presence of lumbosacral radiculopathy identified with electrodiagnostic testing is a favorable prognostic factor for recovery in low back pain-related disability regardless of physical therapy treatment received.

Clinical usefulness of electrodiagnostic study to predict surgical outcomes in lumbosacral disc herniation or spinal stenosis

PURPOSE

Although surgeries have been performed for the treatment of lumbar disc herniation (LDH) or lumbar spinal stenosis (LSS), not all patients who undergo surgery are satisfied with the outcome. Electrodiagnostic study (EDX) can assess the physiological functions of nerve roots with higher specificity and relate better with clinical manifestations. The purpose of this study was to examine how EDX can predict surgical outcomes in patients with LDH and LSS and to compare the predicted values of EDX with other clinical factors and MRI findings.

METHODS

Patients diagnosed with LDH or LSS without neurological deficits, who underwent EDX before lumbar surgery, were selected and analyzed. Patients were divided into groups of successful and unsuccessful surgical outcomes according to a modified MacNab classification. We obtained pre-operative clinical data, radiological results, and EDX results.

RESULTS

Using EDX, radiculopathy was found in 236 patients (52.7%) in the study population. Radiculopathy on EDX was significantly related only to unsuccessful surgical outcomes. The association of spondylolisthesis showed the trends towards unsuccessful surgical outcome, despite statistical insignificance.

CONCLUSIONS

EDX detected functional abnormalities of nerve roots that did not show clinical manifestation and did not appear compressed on MRI. These abnormalities are important predictive factors for surgical outcomes in patients with LDH or LSS. Therefore, pre-operative EDX is a clinically useful method to predict surgical prognosis.

The relationship between history and physical examination findings and the outcome of electrodiagnostic testing in patients with sciatica referred to physical therapy

STUDY DESIGN

Cross-sectional diagnostic accuracy study.

OBJECTIVE

To investigate the relationship between history and physical examination findings and the outcome of electrodiagnostic testing in patients with sciatica referred to physical therapy.

BACKGROUND

Electrodiagnostic testing is routinely used to evaluate patients with sciatica. Recent evidence suggests that the presence of radiculopathy identified with electrodiagnostic testing may predict better functional outcomes in these patients. While some patient history and physical examination findings have been shown to predict the presence of disc herniation or neurological insult, little is known about their relationship to the results of electrodiagnostic testing.

METHODS

Electrodiagnostic testing was performed on 38 patients with sciatica who participated in a randomized trial that compared different physical therapy interventions. The diagnostic gold standard was the presence or absence of radiculopathy, based on the results of the needle electromyographic examination. Diagnostic sensitivity and specificity values were calculated, along with corresponding likelihood ratios, for select patient history and physical examination variables.

RESULTS

No significant relationship was found between select patient history and physical examination findings, analyzed individually or in combination, and the outcome of electrodiagnostic testing. Diagnostic sensitivity values ranged from 0.03 (95% confidence interval [CI]: 0.00, 0.24) to a high of 0.95 (95% CI: 0.72, 0.99), and specificity values ranged from 0.10 (95% CI: 0.02, 0.34) to a high of 0.95 (95% CI: 0.72, 0.99). Positive likelihood ratios ranged from 0.15 (95% CI: 0.01, 2.87) to a high of 2.33 (95% CI: 0.71, 7.70), and negative likelihood ratios ranged from 2.00 (95% CI: 0.35, 11.48) to a low of 0.50 (95% CI: 0.03, 8.10).

CONCLUSION

In this investigation, the relationship between patient history and physical examination findings and the outcome of electrodiagnostic testing among patients with sciatica was not found to be statistically significant or clinically meaningful. However, given the small sample size and corresponding large CIs, these results should be considered with caution, recognizing that some of the history and physical examination variables may prove useful in future research. These findings suggest that electrodiagnostic testing is essential to identify the subgroup of patients with sciatica who have measurable nerve injury consistent with radiculopathy, which may be an important prognostic factor for recovery. Level of Evidence Diagnosis, level 3b-. J Orthop Sports Phys Ther 2014;44(7):508-517. Epub 22 May 2014. doi:10.2519/jospt.2014.5002.

Role of electrodiagnosis in patients being considered for epidural steroid injections

Electrodiagnostic (EDX) evaluation, and, more specifically, electromyography (EMG), has a well-established role in the diagnostic confirmation of cervical and lumbar radiculopathy. The role of EMG in prognostication, however, is less established and remains a topic of debate. The purpose of this article is to evaluate the diagnostic and prognosticating role of EMG in cervical and lumbar radiculopathies, and to assess the utility of EMG in predicting outcomes after epidural steroid injections (ESI). A review of the existing literature strongly supports a prognosticating role for EDX in predicting outcomes after lumbar ESI in lumbosacral radiculopathies (LSR). Although limited research regarding outcome prediction after cervical ESI in cervical radiculopathies has been performed, no study has specifically evaluated the utility of EMG in predicting outcomes for cervical ESI, and this topic requires further investigation. An EDX evaluation can provide clinicians with accurate and reliable diagnostic information (level I or level II evidence) in the evaluation of patients with lumbosacral radiculopathies, and can provide more valid prognostic information (level I evidence) regarding potential benefits of lumbar ESI. An EDX evaluation, therefore, can enhance a clinician's ability to advise patients on the most appropriate and efficacious evaluation and management plan for the treatment of painful radiculopathies.

Changes in electromyographic results of patients with lumbar radiculopathy: a follow-up study

OBJECTIVE

To assess the neurophysiologic changes in a group of patients with lumbar radiculopathy 5 to 12 months after their first electromyographic examination.

DESIGN

A prospective group of patients with a case definition of lumbar radiculopathy was reassessed between 5 and 12 months after their first clinical, functional, imaging, and neurophysiologic evaluation. Both the lumbar paraspinals (in which the mini-mapping technique was used) and the same lower limb muscles were explored in every patient. Relevant abnormalities were (1) positive sharp waves/fibrillation potentials, (2) polyphasic motor unit potentials, and (3) large-amplitude/long-duration motor unit potentials. Patients were sorted into 5 groups based on the type and distribution of neurophysiologic abnormalities: from 0 (no abnormalities) to 4 (denervation signs in 2 lower limb muscles and paraspinals). Patients' subjective perception of any improvement or worsening of their condition was also recorded.

SETTING

A referral center for neurophysiologic evaluation.

PARTICIPANTS

A consecutive sample of patients (N=91) with a clinical definition of lumbar radiculopathy (lumbar pain radiating down the leg and below the knee) referred for neurophysiologic assessment was selected for an initial clinical, functional, and neurophysiologic evaluation. Patients were called for a second evaluation (between 5 and 12mo). Thirty-eight (42% of the initial sample) were willing/eligible for the second evaluation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Changes in (1) electromyographic results; (2) patients' subjective perception of pain; and (3) quality of life, based on the Roland-Morris Questionnaire and Medical Outcomes Study 36-Item Short-Form Health Survey scores.

RESULTS

Paraspinal muscles were most frequently affected. Neurophysiologic abnormalities had improved on reassessment. Clinical improvement was more significant for those patients with initially abnormal electromyographic results.

CONCLUSIONS

There was clinical as well as electromyographic improvement in patients with lumbar radiculopathy within the first year of the initial diagnosis.

Are electrodiagnostic study findings related to a patient's response to epidural steroid injection?

OBJECTIVE

To determine if improvements in pain after epidural steroid injections (ESIs) were related to electromyographic (EMG) findings in patients with radicular symptoms and clinical findings consistent with radiculopathy.

DESIGN

Retrospective chart review.

SETTING

Multisite spine clinic.

PATIENTS

Data were analyzed from 89 patients who had needle EMG within 6 months of ESI between 2005 and 2008.

METHODS

Clinical and demographic data and results of EMG testing from qualified patients were recorded from patient charts at least 10 days after ESI. Evidence of radiculopathy on EMG reports was classified as positive, normal, or equivocal. In all 3 EMG groups, the percentage of patients who had 50% improvement in leg pain after ESI was noted. As a secondary analysis, improvement in pre-ESI to post-ESI leg and back pain scores in the EMG groups were compared.

OUTCOME MEASUREMENTS

The clinical outcome measurements were visual analog scale (VAS) scores assessing leg and back pain. ESI relief was defined as at least 50% improvement in the VAS score assessing leg pain after the injection.

RESULTS

EMG findings were normal in 47.2%, positive in 31.5%, and equivocal in 21.3% of patients. No significant differences were found in the percentages of patients experiencing a positive response to the ESI with respect to EMG findings. Forty-three percent of patients with normal EMG findings (18/42), 25.0% of patients with positive EMG findings (7/28), and 31.6% patients with equivocal EMG findings (6/19) had relief after ESI. In all 3 EMG groups, a statistically significant improvement in mean VAS scores was found after ESI.

CONCLUSIONS

Mean leg and back pain scores improved significantly after ESI in all 3 EMG groups: those with positive, normal, and equivocal findings. Results of this study do not suggest that ESI is contraindicated in patients with normal EMG findings.