Lumbar selective nerve root block
Selective nerve root block (SNRB) can identify the pain-generating nerve root; however, its diagnostic accuracy remains controversial due to the potential spread of the injectate 1).
Selective Nerve Root Block (SNRB) is practiced as a part of the management of radicular pain due to a particular affected nerve root in both cervical and lumbar regions 2) 3) 4).
A Systematic review aimed to examine the diagnostic accuracy of selective nerve root blocks (SNRBs) to identify patients most likely to benefit from lumbar decompression surgery.
INFORMATION SOURCES: MEDLINE (Ovid), MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Science Citation Index, Biosis, LILACS, Dissertation abstracts and National Technical Information Service from inception to 2018.
Risk of bias and applicability was assessed using the QUADAS-2 tool. Beynon et al., performed random-effects logistic regression to meta-analyse studies grouped by reference standard.
6 studies (341 patients) were included in this review. All studies were judged at high risk of bias. There was substantial heterogeneity across studies in sensitivity (range 57%-100%) and specificity (10%-86%) estimates. Four studies were diagnostic cohort studies that used either intraoperative findings during surgery (pooled sensitivity: 93.5% [95% CI 84.0 to 97.6]; specificity: 50.0% [16.8 to 83.2]) or 'outcome following surgery' as the reference standard (pooled sensitivity: 90.9% [83.1 to 95.3]; specificity 22.0% [7.4 to 49.9]). Two studies had a within-patient case-control study design, but results were not pooled because different types of control injections were used.
They found limited evidence which was of low methodological quality indicating that the diagnostic accuracy of SNRB is uncertain and that specificity in particular may be low. SNRB is a safe test with a low risk of clinically significant complications, but it remains unclear whether the additional diagnostic information it provides justifies the cost of the test 5).
The purpose of a study was to investigate the clinical symptomatology of discopathies before and 7 days after treatment with one of the following: intravenous dexamethasone, selective nerve root block (SNRB), and systemic treatment with different nonsteroidal antiinflammatory drugs (NSAIDs). We conducted a retrospective study of 81 male and female patients aged 18 years and above who had radicular pain and were referred to our facility over a 7-year period. Of the 100 patients assessed for eligibility, 19 patients were not included in the study due to malignancy or surgical intervention, 32 patients received intravenous dexamethasone, 24 patients received SNRB, and 25 received various NSAIDs as the control group. The visual analog scale, straight leg raise test and neurological deficits were assessed to evaluate the patients before and after receiving treatment. All patients underwent spinal computed tomography to confirm the diagnosis of disc herniation. Pearson chi-squared test, Kruskal-Wallis test, and Mann-Whitney test were used to evaluate the results. Visual analog scale scores and the ability to perform straight leg raise test significantly improved after treatment with dexamethasone, SNRB, and NSAIDs. However, clinical improvement was significantly better in both the dexamethasone and SNRB groups than in the control group. Motor deficits improved significantly after dexamethasone treatment alone. Dexamethasone and SNRB are useful and safe treatment options for treating patients with acute radicular pain. Randomized, double-blinded, control studies are warranted 6).
Guyot, studied a series of 298 patients who received a selective nerve root injection and made a comparative study dividing them into 2 groups according to the drugs used. In group A, they used betamethasone 6 mg and lidocaine, while in group B, triamcinolone 60 mg and bupivacaine were used for the procedure. They evaluated the patients for a period of at least 8 months, assuming the need for surgical therapy as the failure of the procedure.
Both groups had 149 patients with similar etiological characteristics. Forty-seven patients (16%) required surgery to relieve pain with a similar distribution between groups (24 from group A and 23 from group B). Time between nerve root injection and surgery was 86.79 (14-360) days on average in group A and 75.76 (2-180) days in group B with no statistical difference (P = .67). Only one complication was documented, an anaphylactic shock in a patient in group B.
Based on these results, they found no difference in the type of steroid or local anesthetic used for selective nerve root injections 7).
In a case series of 40 patients the effect of SNRB was typically short acting in majority of patients and recurrence is expected. It creates a window period with reduced pain but of varied intervals depending on the pathology. It did not alter the prognosis in those with severe disease where surgery is well indicated. Level of Evidence - Level 4 8).
A total of 105 block anesthetics were performed under fluoroscopic guidance in 47 consecutive patients with pure radiculopathy from a single confirmed level: 47 blocks were performed at the symptomatic level, and 58 were performed at the adjacent asymptomatic “control” level. Contrast and local anesthetics were injected, and spot radiographs were taken in all cases. We calculated the diagnostic value of the block anesthetics using concordance with the injected level. We analyzed the potential causes of false results using spot radiographs.
On the basis of a definition of a positive block as 70% pain relief, determined by receiver-operator characteristic (ROC) analysis, diagnostic lumbar selective nerve root block anesthetics had a sensitivity of 57%, a specificity of 86%, an accuracy of 73%, a positive predictive value of 77%, and a negative predictive value of 71%. False-negatives were due to the following causes identifiable on spot radiographs: insufficient infiltration, insufficient passage of the injectate, and intraepineural injections. On the other hand, false-positives resulted from overflow of the injectate from the injected asymptomatic level into either the epidural space or symptomatic level.
The accuracy of diagnostic lumbar selective nerve root blocks is only moderate. To improve the accuracy, great care should be taken to avoid inadequate blocks and overflow, and to precisely interpret spot radiographs 9).
S1 nerve root block
Case series
The subjects were 112 patients aged over 80 years (mean age: 84 years; 45 men and 67 women ) with medication-resistant LCS without cauda equina syndrome who underwent SNRB. Cases with acute-onset lumbar disc herniation were excluded. We retrospectively investigated and compared the presence or absence of surgery, effect of SNRB, number of procedures, duration of disease, and magnetic resonance imaging findings. Patients who could avoid the surgery by SNRB were defined as the effective group. Patients whose symptoms were not relieved by SNRB and who underwent surgery and those whose symptoms were not relieved but who continued conservative treatment were defined as the ineffective group. A total of one to seven SNRBs were performed in both groups, and the same spine surgeon performed the entire procedure from SNRB to surgery.
Results: There were 86 nonoperative patients (69 effective cases) and 26 operative patients; the overall rate of effectiveness was 61% (69/112 patients). The area of the spinal canal at the responsible level was 108.63 mm2 in the effective group compared with 77.06 mm2 in the ineffective group. This was significantly narrower in the ineffective group (p=0.0094). There was no significant difference in the duration of illness, number of blocks, or hernia complication rate between the groups. No patient experienced severe neuralgia that may have been caused by neuropathy during SNRB.
Discussion: Our outcome showed that more than 60% of older patients with LCS showed symptomatic improvement with SNRB. SNRB can be performed relatively safely in the elderly and appears to be a favorable treatment option for older patients with various risks, such as poor general condition 10).
prospective study included 50 patients who underwent an SNRB and were followed for 3 months. Numerical Rating Scale (NRS) for back and leg pain and Oswestry Disability Index (ODI) and Depression Anxiety Stress Scales-21 (DASS-21) scores were collected. At the final follow-up at 3 months, the number of patients who underwent surgery was ascertained.
Results: Forty-two of 50 (84%) patients avoided the surgery with a reduction in mean preinjection NRS for back and leg pain from 7.5 (SD 1.33) and 7.7 (SD 1.35) to 3.1 (SD 1.69) and 2.3 (SD 1.14) (P < 0.001), respectively, within the 30 minutes after injection. The pain relief was sustained until the last follow-up. The ODI score also decreased from a mean preinjection level of 59.4 (SD 14.69) to 26.3 (SD 9.43) (P < 0.001) at 3 months. The mean preinjection depression score was higher in patients who had recurrence of pain and eventually underwent surgery.
Conclusion: Early administration of an SNRB in the course of lumbar radiculopathy is recommended as it provides instantaneous and sustained relief of back and leg pain and disability in a majority of patients.
Clinical relevance: SNRB should be administered early in the course of management of lumbar radiculopathy and should not be delayed until after other non-surgical modalities have failed.
Level of evidence: 2 11).
Case reports
An 80-year-old man with left lower limb radicular pain diagnosed as L4-5, L5-S1 intervertebral disc protrusion, spinal canal stenosis, and degenerative scoliosis underwent lumbar surgery. Four months after surgery, he experienced left lower limb radicular pain. After designing the puncture route based on X-ray film, they performed a combined ultrasound-guided L4 and L5 paravertebral block. With his improved pain control, his functional status and ability to perform daily activities also markedly improved.
Real-time ultrasound-guided lumbar paravertebral block performed with a pre-designed route on X-ray film can provide a simple and safe way to relieve radicular pain in FBSS 12).
Steroids for Lumbar selective nerve root block
Selective nerve root block has been widely used to treat degenerative disc disease (DDD), but no detailed research data is provided to compare the efficacy of epidural injection of anesthetics with or without steroids on the DDD treatment.
Objectives: This study aimed to provide the first comparison of steroids + local anesthetic (LA) or LA alone for the treatment of DDD.
Study design: We systematically searched PubMed, Medline, Embase, and Cochrane. A systemic review and meta-analysis were performed to assess the clinical efficacy of both the steroids + LA group and the LA alone group, and subgroup analysis was also adopted.
Setting: A systematic review and meta-analysis using a random effects model on randomized controlled studies (RCTs).
Methods: After reviewing titles, abstracts, risk of bias, and full texts of 15,889 studies that were chosen following removal of duplicates after the initial database search, finally, 19 RCTs were included. Pain rating, functional score, follow-up period, and other-related data were extracted from these included works, and the effect size and statistical significance were calculated by the random effects model. The quality and level of the derived evidence were assessed by means of the Grading of Recommendations Assessment, Development and Evaluation method.
Results: In terms of the Numeric Rating Scale (NRS-11) and Oswestry Disability Index (ODI) at one year, the combination of steroids + LA was obviously superior to LA. Subgroup analysis suggested that the combination of steroids + LA was more effective than LA alone in regard to the ODI in the lumbar group within 2 years. The opioids intake of patients treated by LA alone was less than that of the steroids + LA group within 3 months, and LA alone was more effective in pain score reduction, with more than 50% within 6 months in the interlaminar injection group. However, the combination of steroids + LA was more effective when alleviating the NRS-11 within 18 months in the caudal injection group.
Limitations: Firstly, this analysis was inconsistent in technique, dosage, injection frequency, and follow-up period of epidural injections. Such differences may compromise the reported efficacy. Secondly, adverse reactions arising out of the 2 groups were not examined in that the included RCTs did not provide the data. Thirdly, different injection methods would compromise the outcomes, and no subgroup analysis was performed on different injection methods. Finally, these included articles that were mainly sourced from Manchikanti's team, and thus biased to some extent.
Conclusions: The addition of steroids to anesthetic injectates was associated with a better NRS-11 and ODI compared with LA alone within one year in patients with DDD. Furthermore, the improvement of the ODI was observed within 2 years in patients with lumbar DDD 13).