Prognostic factors associated with outcome following an epidural steroid injection for disc-related sciatica: a systematic review and narrative synthesis

PURPOSE

Clinical guidelines recommend epidural steroid injection (ESI) as a treatment option for severe disc-related sciatica, but there is considerable uncertainty about its effectiveness. Currently, we know very little about factors that might be associated with good or poor outcomes from ESI. The aim of this systematic review was to synthesise and appraise the evidence investigating prognostic factors associated with outcomes following ESI for patients with imaging confirmed disc-related sciatica.

METHODS

The search strategy involved the electronic databases Medline, Embase, CINAHL Plus, PsycINFO and reference lists of eligible studies. Selected papers were quality appraised independently by two reviewers using the Quality in Prognosis Studies tool. Between-study heterogeneity precluded statistical pooling of results.

RESULTS

3094 citations were identified; 15 studies were eligible. Overall study quality was low with all judged to have moderate or high risk of bias. Forty-two prognostic factors were identified but were measured inconsistently. The most commonly assessed prognostic factors were related to pain and function (n = 10 studies), imaging features (n = 8 studies), patient socio-demographics (n = 7 studies), health and lifestyle (n = 6 studies), clinical assessment findings (n = 4 studies) and injection level (n = 4 studies). No prognostic factor was found to be consistently associated with outcomes following ESI. Most studies found no association or results that conflicted with other studies.

CONCLUSIONS

There is little, and low quality, evidence to guide practice in terms of factors that predict outcomes in patients following ESI for disc-related sciatica. The results can help inform some of the decisions about potential prognostic factors that should be assessed in future well-designed prospective cohort studies.

Early Postoperative Iatrogenic Neuropraxia After Lumbar Disc Herniation Surgery: Analysis of 87 Cases

BACKGROUND

Postoperative early neuropraxia after lumbar disc herniation surgery is common. The emergence of new paresthesia findings with increased sensory and motor deficits in the postoperative period suggests iatrogenic neuropraxia. This study aimed to discuss the causes and prognosis of iatrogenic neuropraxia detected in the early postoperative period in patients who have been operated on for lumbar disc herniation.

METHODS

Cases with postoperative iatrogenic neuropraxia were determined retrospectively. Deficits were evaluated at intervals of 0-2 hours, 2-12 hours, 12-24 hours, and 24-48 hours. The cases were evaluated in 2 groups as those who underwent aggressive discectomy and simple discectomy. In addition, the treatment results were compared between the 2 groups as the cases that were treated and not treated with methylprednisolone.

RESULTS

The iatrogenic neuropraxia rate was significantly higher in patients who underwent aggressive discectomy. Although it was observed that paresthesia findings improved more rapidly in cases treated with methylprednisolone, no difference was found between the 2 groups in terms of its effects on the motor deficit.

CONCLUSIONS

Iatrogenic neuropraxia is a finding whose cause cannot be determined by quantitative criteria. It is common in patients who underwent aggressive discectomy. Methylprednisolone treatment is effective in recovering the paresthesia finding faster and may show that the radicular injury is in the neuropraxia stage in the early period.

Multicenter study evaluating factors associated with treatment outcome for low back pain injections

BACKGROUND

There has been a worldwide surge in interventional procedures for low back pain (LBP), with studies yielding mixed results. These data support the need for identifying outcome predictors based on unique characteristics in a pragmatic setting.

METHODS

We prospectively evaluated the association between over two dozen demographic, clinical and technical factors on treatment outcomes for three procedures: epidural steroid injections (ESIs) for sciatica, and sacroiliac joint (SIJ) injections and facet interventions for axial LBP. The primary outcome was change in patient-reported average pain intensity on a numerical rating scale (average NRS-PI) using linear regression. For SIJ injections and facet radiofrequency ablation, this was average LBP score at 1 and 3 months postprocedure, respectively. For ESI, it was average leg pain 1- month postinjection. Secondary outcomes included a binary indicator of treatment response (success).

RESULTS

346 patients were enrolled at seven hospitals. All groups experienced a decrease in average NRS-PI (p<0.0001; mean 1.8±2.6). There were no differences in change in average NRS-PI among procedural groups (p=0.50). Lower baseline pain score (adjusted coefficient -0.32, 95% CI -0.48 to -0.16, p<0.0001), depressive symptomatology (adjusted coefficient 0.076, 95% CI 0.039 to 0.113, p<0.0001) and obesity (adjusted coefficient 0.62, 95% CI 0.038 to 1.21, p=0.037) were associated with smaller pain reductions. For procedural outcome, depression (adjusted OR 0.94, 95% CI 0.91, 0.97, p<0.0001) and poorer baseline function (adjusted OR 0.59, 95% CI 0.36, 0.96, p=0.034) were associated with failure. Smoking, sleep dysfunction and non-organic signs were associated with negative outcomes in univariate but not multivariate analyses.

CONCLUSIONS

Identifying treatment responders is a critical endeavor for the viability of procedures in LBP. Patients with greater disease burden, depression and obesity are more likely to fail interventions. Steps to address these should be considered before or concurrent with procedures as considerations dictate.

TRIAL REGISTRATION NUMBER

NCT02329951.

Low back pain

Low back pain covers a spectrum of different types of pain (eg, nociceptive, neuropathic and nociplastic, or non-specific) that frequently overlap. The elements comprising the lumbar spine (eg, soft tissue, vertebrae, zygapophyseal and sacroiliac joints, intervertebral discs, and neurovascular structures) are prone to different stressors, and each of these, alone or in combination, can contribute to low back pain. Due to numerous factors related to low back pain, and the low specificity of imaging and diagnostic injections, diagnostic methods for this condition continue to be a subject of controversy. The biopsychosocial model posits low back pain to be a dynamic interaction between social, psychological, and biological factors that can both predispose to and result from injury, and should be considered when devising interdisciplinary treatment plans. Prevention of low back pain is recognised as a pivotal challenge in high-risk populations to help tackle high health-care costs related to therapy and rehabilitation. To a large extent, therapy depends on pain classification, and usually starts with self-care and pharmacotherapy in combination with non-pharmacological methods, such as physical therapies and psychological treatments in appropriate patients. For refractory low back pain, a wide range of non-surgical (eg, epidural steroid injections and spinal cord stimulation for neuropathic pain, and radiofrequency ablation and intra-articular steroid injections for mechanical pain) and surgical (eg, decompression for neuropathic pain, disc replacement, and fusion for mechanical causes) treatment options are available in carefully selected patients. Most treatment options address only single, solitary causes and given the complex nature of low back pain, a multimodal interdisciplinary approach is necessary. Although globally recognised as an important health and socioeconomic challenge with an expected increase in prevalence, low back pain continues to have tremendous potential for improvement in both diagnostic and therapeutic aspects. Future research on low back pain should focus on improving the accuracy and objectivity of diagnostic assessments, and devising treatment algorithms that consider unique biological, psychological, and social factors. High-quality comparative-effectiveness and randomised controlled trials with longer follow-up periods that aim to establish the efficacy and cost-effectiveness of low back pain management are warranted.

Nociplastic pain: towards an understanding of prevalent pain conditions

Nociplastic pain is the semantic term suggested by the international community of pain researchers to describe a third category of pain that is mechanistically distinct from nociceptive pain, which is caused by ongoing inflammation and damage of tissues, and neuropathic pain, which is caused by nerve damage. The mechanisms that underlie this type of pain are not entirely understood, but it is thought that augmented CNS pain and sensory processing and altered pain modulation play prominent roles. The symptoms observed in nociplastic pain include multifocal pain that is more widespread or intense, or both, than would be expected given the amount of identifiable tissue or nerve damage, as well as other CNS-derived symptoms, such as fatigue, sleep, memory, and mood problems. This type of pain can occur in isolation, as often occurs in conditions such as fibromyalgia or tension-type headache, or as part of a mixed-pain state in combination with ongoing nociceptive or neuropathic pain, as might occur in chronic low back pain. It is important to recognise this type of pain, since it will respond to different therapies than nociceptive pain, with a decreased responsiveness to peripherally directed therapies such as anti-inflammatory drugs and opioids, surgery, or injections.

Back Pain in Outer Space

Space travel has grown during the past 2 decades, and is expected to surge in the future with the establishment of an American Space Force, businesses specializing in commercial space travel, and National Aeronautics and Space Administration's planned sustained presence on the moon. Accompanying this rise, treating physicians are bracing for a concomitant increase in space-related medical problems, including back pain. Back pain is highly prevalent in astronauts and space travelers, with most cases being transient and self-limiting (space adaptation back pain). Pathophysiologic changes that affect the spine occur during space travel and may be attributed to microgravity, rapid acceleration and deceleration, and increased radiation. These include a loss of spinal curvature, spinal muscle atrophy, a higher rate of disc herniation, decreased proteoglycan and collagen content in intervertebral discs, and a reduction in bone density that may predispose people to vertebral endplate fractures. In this article, the authors discuss epidemiology, pathophysiology, prevention, treatment, and future research.

Waddell (Nonorganic) Signs and Their Association With Interventional Treatment Outcomes for Low Back Pain

BACKGROUND

The rising use of injections to treat low back pain (LBP) has led to efforts to improve selection. Nonorganic (Waddell) signs have been shown to portend treatment failure for surgery and other therapies but have not been studied for minimally invasive interventions.

METHODS

We prospectively evaluated the association between Waddell signs and treatment outcome in 3 cohorts: epidural steroid injections (ESI) for leg pain and sacroiliac joint (SIJ) injections and facet interventions for LBP. Categories of Waddell signs included nonanatomic tenderness, pain during sham stimulation, discrepancy in physical examination, overreaction, and regional disturbances divulging from neuroanatomy. The primary outcome was change in patient-reported "average" numerical rating scale for pain intensity (average NRS-PI), modeled as a function of the number of Waddell signs using simple linear regression. Secondary outcomes included a binary indicator of treatment response. We conducted secondary and sensitivity analyses to account for potential confounders.

RESULTS

We enrolled 318 patients: 152 in the ESI cohort, 102 in the facet cohort, and 64 in the SIJ cohort, having sufficient data for primary analysis on 308 patients. Among these, 62% (n = 192) had no Waddell signs, 18% (n = 54) had 1 sign, 11% (n = 33) had 2, 5% (n = 16) had 3, 2% (n = 7) had 4, and about 2% (n = 6) had all 5 signs. The mean change in average NRS-PI in each of these 6 groups was -1.6 ± 2.6, -1.1 ± 2.7, -1.5 ± 2.5, -1.6 ± 2.6, -1 ± 1.5, and 0.7 ± 2.1, respectively, and their corresponding treatment failure rates were 54% (102 of 192), 67% (36 of 54), 70% (23 of 33), 75% (12 of 16), 71% (5 of 7), and 83% (5 of 6). In the primary analysis, an increasing number of Waddell signs were not associated with a significant decrease in average NRS-PI (coefficient [Coef] = 0.19; 95% confidence interval [CI], -0.43 to 0.05; P = .12). A higher number of Waddell signs were associated with treatment failure, with a 1.35 increased odds of treatment failure per cumulative number of signs (P = .008).

CONCLUSIONS

Whereas this study found no consistent relationship between Waddell signs and decreased mean pain scores, a significant relationship between the number of Waddell signs and treatment failure was observed.