Diagnostic value of the nerve root sedimentation sign, a radiological sign using magnetic resonance imaging, for detecting lumbar spinal stenosis: a meta-analysis

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of lumbar spinal stenosis, 2021 - Secondary publication

BACKGROUND

The Japanese Orthopaedic Association (JOA) guideline for the management of lumbar spinal stenosis (LSS) was first published in 2011. Since then, the medical care system for LSS has changed and many new articles regarding the epidemiology and diagnostics of LSS, conservative treatments such as new pharmacotherapy and physical therapy, and surgical treatments including minimally invasive surgery have been published. In addition, various issues need to be examined, such as verification of patient-reported outcome measures, and the economic effect of revised medical management of patients with lumbar spinal disorders. Accordingly, in 2019 the JOA clinical guidelines committee decided to update the guideline and consequently established a formulation committee. The purpose of this study was to describe the formulation we implemented for the revision of the guideline, incorporating the recent advances of evidence-based medicine.

METHODS

The JOA LSS guideline formulation committee revised the previous guideline based on the method for preparing clinical guidelines in Japan proposed by the Medical Information Network Distribution Service in 2017. Background and clinical questions were determined followed by a literature search related to each question. Appropriate articles based on keywords were selected from all the searched literature. Using prepared structured abstracts, systematic reviews and meta-analyses were performed. The strength of evidence and recommendations for each clinical question was decided by the committee members.

RESULTS

Eight background and 15 clinical questions were determined. Answers and explanations were described for the background questions. For each clinical question, the strength of evidence and the recommendation were both decided, and an explanation was provided.

CONCLUSIONS

The 2021 clinical practice guideline for the management of LSS was completed according to the latest evidence-based medicine. We expect that this guideline will be useful for all medical providers as an index in daily medical care, as well as for patients with LSS.

[Lumbar spinal stenosis]

Lumbar spinal stenosis (LSS) represents a frequent degenerative condition, however, striking a clear correlation between typical symptoms and imaging features remains a challenge. Reasons are a high prevalence of radiological LSS in the older population, a considerable percentage of asymptomatic LSS and the existence of differential diagnoses with similar symptomatology. This discrepancy also affects the outcomes - especially of surgically treated patients with LSS. When considering surgical decompression of LSS, the decision with regards to additive instrumentation and/or fusion remains a controversial point of discussion, in particular at the presence of degenerative spondylolisthesis. Recent, well-designed studies, however, clearly point towards a non-inferiority of decompression alone as opposed to the more invasive strategies.

The association between clinical symptoms of lumbar spinal stenosis and MRI axial imaging findings

Purpose:

In diagnosing lumbar spinal stenosis (LSS), Magnetic Resonance Imaging (MRI) is appropriate to confirm the presence of anatomical stenosis of the spinal canal or compression of the nerve roots. However, it is known that morphological LSS is often present in asymptomatic subjects. There is still controversy about the relationship between anatomical LSS and symptomatic LSS. The aim of this study was to assess the association between qualitative imaging findings on MRI of the lumbar spine and symptomatic LSS.

Patients and methods:

This was a cross-sectional study of 239 volunteers from an epidemiological survey that included 1,862 participants in total. MRI of the lumbar spine was evaluated in four categories: morphological grading of central stenosis and lateral recess stenosis, presence of the sedimentation sign, and severity of facet joint effusion. The relationship between these morphological evaluations and typical LSS symptoms as assessed by the self-administered, self-reported history questionnaire for lumbar spinal stenosis (LSS-SSHQ) was investigated by multiple logistic regression analysis.

Results:

The odds ratio of the most severe central stenosis to no stenosis was 15.5 (95%CI: 1.4-164.9). Only the most severe central stenosis was associated with typical LSS symptoms, but not all cases with typical LSS symptoms were due to severe central stenosis.

Conclusion:

Extreme severe central stenosis was strongly related to typical LSS symptoms. However, although subjects with severe central stenosis showed symptoms suggestive of LSS, these subjects did not always show typical LSS symptoms.

Cerebrospinal fluid signal loss sign: assessment of a new radiological sign in lumbar spinal stenosis

PURPOSE

Sedimentation sign was reported to have high sensitivity and specificity for diagnosis of lumbar spinal stenosis (LSS). We aimed to determine cerebrospinal fluid signal loss (CSFSL) at the intervertebral disc levels in the sagittal plane using a numerical scoring system and to evaluate the diagnostic value of this method in differential diagnosis of LSS and non-specific low back pain (LBP) and compare it with SS.

MATERIALS AND METHODS

We included consecutive patients between 50 and 80 years old, with lumbar spinal MRI examination in our institution. These patients were divided into two groups as LSS and LBP, according to symptoms and radiological findings. CSFSL sign was evaluated for both groups by two radiologists independently, using MR images. Sensitivity and specificity of both signs were calculated.

RESULTS

A total of 406 patients (98 LSS and 308 non-specific LBP) were included. SS and CSFSL sign had a sensitivity of 90.8% and 82.7% and specificity of 75.4% and 84.1% in the whole cohort, respectively. When patients were grouped by dural sac cross-sectional areas (CSA), sensitivity and specificity of SS were 100% and 4.4%, 87.5% and 31.8%, and 41.7% and 76%, respectively, and sensitivity and specificity of CSFSL sign were 95.7% and 11.1%, 75% and 77.3%, and 16.7 and 92% for severe (CSA < 80 mm2), moderate (CSA: 80-100 mm2), mild (CSA: 100-120 mm2) radiologic stenosis, respectively. In moderate stenosis, accuracies of SS and CSFSL sign were 76.3% and 55.3%, respectively.

CONCLUSION

CSFSL sign might be used to distinguish LSS from LBP and unlike SS it is successful in moderate stenosis.

Nerve root sedimentation sign on MRI: A triage screen for leg dominant symptoms?

PURPOSE

Surgical indications for lumbar spinal stenosis are controversial, but most agree that leg dominant pain is a better predictor of success after decompression surgery. The objective of this study is to analyze the ability of the Nerve Root Sedimentation Sign (SedSign) on MRI to differentiate leg dominant symptoms from non-specific low back pain.

METHODS

This was a retrospective review of 367 consecutive patients presenting with back and/or leg pain. Baseline clinical characteristics included Oswestry disability index (ODI), visual analog pain scores, EuroQol Group 5-Dimension Self-Report (EQ5D) and Saskatchewan Spine Pathway Classification (SSPc). Inter- and intra-rater reliability for SedSign was 73% and 91%, respectively (3 examiners).

RESULTS

SedSign was positive in 111 (30.2%) and negative in 256 (69.8%) patients. On univariate analysis, a positive SedSign was correlated with age, male sex, several ODI components, EQ5D mobility, cross-sectional area (CSA) of stenosis, antero-posterior diameter of stenosis, and SSPc pattern 4 (intermittent leg dominant pain). On multivariate analysis, SedSign was associated with age, male sex, CSA stenosis and ODI walking distance. Patients with a positive SedSign were more likely to be offered surgery after referral (OR 2.65). The sensitivity and specificity for detecting all types of leg dominant pain were 37.4 and 82.8, respectively (ppv 77.5%, npv 43.8%).

CONCLUSIONS

Patients with a positive SedSign were more likely to be offered surgery, in particular non-instrumented decompression. The SedSign has high specificity for leg dominant pain, but the sensitivity is poor. As such, its use in triaging appropriate surgical referrals is limited.

The Correlation Between Negative Nerve Root Sedimentation Sign and Gravity: A Study of Upright Lumbar Multi-Positional Magnetic Resonance Images

STUDY DESIGN

Retrospective upright MRI study.

OBJECTIVE

To validate the presence of positive and negative nerve root sedimentation signs on multi-positional MRI in the upright position and explore the relationship between negative nerve root sedimentation and gravity.

METHODS

T2-weighted axial multi-positional images in the upright position at the intervertebral disc levels from L1-L2 to L4-L5 in 141 patients with non-specific low back pain were retrospectively assessed. A positive sedimentation sign was defined as the absence of nerve root sedimentation or the absence of dorsal conglomeration of nerve roots within the dural sac. A negative sedimentation sign was defined as nerve root sedimentation dorsally or dorso-laterally like a horseshoe. Intra-and inter-observer reliability was evaluated. The relationship between sedimentation sign and dural sac cross-sectional area (CSA), anterior-posterior (AP) diameter was also explored.

RESULTS

The kappa value of intra-observer reliability was 0.962 and inter-observer reliability was 0.925. Both positive and negative sedimentation signs did appear at all 4 lumbar levels, including L1/2, L2/3, L3/4 and L4/5. A positive sedimentation sign was associated with significantly decreased dural sac CSA and AP diameter at L2/3, L3/4 or L4/5 level when compared to negative sedimentation sign.

CONCLUSIONS

Both negative and positive sedimentation signs appeared at the L1/2, L2/3, L3/4, and L4/5 levels on the upright MRI, which suggested that the presence of nerve roots sedimenting dorsally in patients may not be associated with gravity. Moreover, the current study supports that sedimentation signs on multi-positional MRI images could have the same diagnostic functions as on MRI images.

Percutaneous spinal endoscopy with unilateral interlaminar approach to perform bilateral decompression for central lumbar spinal stenosis: radiographic and clinical assessment

Background

Recently, a percutaneous spinal endoscopy unilateral posterior interlaminar approach to perform bilateral decompression has been proposed for use in treatment of lumbar spinal stenosis, As a development and supplement to traditional surgery, its advantages regarding therapeutic effects and prognosis, such as minor soft tissue damage, little intraoperative blood loss, and a quick return to daily life. However, there are few analyses of this surgery with a follow-up of more than 1 year,we conducted this study in order to quantitatively investigate radiographic and clinical efficacies of this surgery for central lumbar spinal stenosis.

Materials and methods

Forty-six patients with central lumbar spinal stenosis were enrolled from January 2017 to July 2018. The visual analog scale (VAS) for back pain and leg pain, Oswestry disability index (ODI), modified MacNab criteria were used to evaluate clinical efficiency at preoperative and postoperative time points. The intervertebral height index (IHI), cross-sectional area of the spinal canal (CSAC), calibrated disc signal (CDS) and spinal stability were examined to assess radiographic decompression efficiency via magnetic resonance imaging and X-ray at preoperative and postoperative time points.

Results

The VAS score for lower back pain and leg pain improved from 7.50 ± 0.78 to 1.70 ± 0.66 and from 7.30 ± 0.79 to 1.74 ± 0.68, respectively, and the ODI improved from 72.35 ± 8.15 to 16.15 ± 4.51. In terms of modified MacNab criteria, 91.3% of the patients achieved good or excellent outcomes. Furthermore, significant changes after surgery were observed for the percentage of CSAC, increasing from 125.3 ± 53.9 to 201.4 ± 78 mm²; however, no significant differences were observed for the remaining measurement indicators.

Conclusions

The clinical and radiographic efficacies of this surgery for central lumbar spinal stenosis were good in short-term follow-up, and this surgery did not cause meaningful changes in IHI, CDS, and spine stability in short-term follow-up. The effect of long-term follow-up needs further investigation.

The nerve root sedimentation sign in diagnosis of lumbar spinal stenosis

BACKGROUND

The nerve root sedimentation sign is a magnetic resonance (MR) sign, shown to be present in central lumbar spinal stenosis. The lack of sedimentation of the nerve roots to the dorsal part of the dural sac is consistent with the positive nerve root sedimentation sign.

PURPOSE

To validate the reliability of the nerve root sedimentation sign in diagnosis of different grades of lumbar spinal canal stenosis.

MATERIAL AND METHODS

This study was a retrospective review of 101 consecutive MR imaging (MRI) studies obtained on patients with clinically suspected lumbar canal stenosis. Based on the minimum anteroposterior (AP) diameter of the dural sac the study sample was classified into two groups: a group with morphological lumbar spinal stenosis; and the group of patients free from stenosis (AP > 12 mm). Patients with stenosis were further subclassified based on its severity: severe stenosis (AP ≤ 10 mm); and moderate stenosis (AP > 10 mm to ≤ 12 mm).

RESULTS

Positive sedimentation sign was identified in 81% of patients with severe lumbar spinal stenosis and 14% of patients with moderate stenosis. No patients without lumbar spinal stenosis had a positive nerve root sedimentation sign. Of patients with a positive nerve root sedimentation sign, 89% presented with neurological claudication.

CONCLUSION

The nerve root sedimentation is a useful tool for identification of patients with both severe clinical and morphological lumbar spinal stenosis; however, its performance in the diagnosis of patients with moderate morphological spinal stenosis is poor.

Lumbar Spinal Stenosis: The Reliability, Sensitivity and Specificity of the Nerve Root Sedimentation Sign

Introduction: This study is to evaluate the reliability, sensitivity and specificity of nerve root sedimentation sign (NRS) in our populations. The NRS is a radiological sign to diagnose lumbar spinal stenosis (LSS). It is claimed to be reliable with high sensitivity and specificity.

Materials and Methods: A total of 82 MRI images from 43 patients in Group A (LSS) and 39 patients in Group B (non LSS) were analysed and compared for the presence of the NRS sign. Two assessors were used to evaluate intra and inter-assessor reliability of this sign based on 56 (33 patients, Group A and 23 patients, Group B). The findings were statistically analysed using SPSS software.

Results: There was a significant association between spinal claudication and leg numbness with LSS (p<0.001 and Kappa=0.857, p<0.001). The inter-assessor reliability was also good (Kappa of 0.786, p<0.001).

Conclusion: The NRS sign has high sensitivity and specificity for diagnosing LSS. The sign also has good intra and inter-assessor reliability.

A Meta-Analysis on the Clinical Significance of Redundant Nerve Roots in Symptomatic Lumbar Spinal Stenosis

OBJECTIVE

Symptomatic lumbar spinal stenosis (LSS), which leads to severe socioeconomic consequences and places a heavy burden on global healthcare system, is a relatively frequent spine disorder. Redundant nerve roots (RNRs) are a relatively common finding in which slender, serpiginous, or tortuous nerve roots are found in the subarachnoid space of the lumbar spine. Previous studies that evaluated the prognostic assessment of RNRs in patients with symptomatic LSS are composed of doubtful results. Therefore, the clinical significance of RNRs in symptomatic LSS is still uncertain. The aim of this meta-analysis is a systematic assessment of the clinical significance of RNR syndrome in symptomatic LSS.

METHODS

This study used a highly sensitive search strategy to identify all published studies in multiple databases up to January 1, 2017. All identified trials were systematically evaluated using specific inclusion and exclusion criteria. Cochrane methodology was also applied to the results of this study.

RESULTS

This study identified 4 relevant studies involving 297 patients. Compared with a non-RNR group, the RNR group results included worse clinical outcomes that were assessed using the Japanese Orthopedic Association scores after surgery (weighted mean difference [WMD], -0.78; 95% confidence interval [CI], -1.26 to -0.29; P = 0.002; I² = 0%), for recovery rate (WMD, -9.87; 95% CI, -15.07 to -4.67; P = 0.0002; I² = 0%), and for older age (WMD, 2.51; 95% CI, 0.45-4.57; P = 0.02; I² = 43%).

CONCLUSIONS

RNR is an entity in association with symptomatic LSS, which may be viewed as a potentially powerful prognostic indicator of worse postoperative functional recovery for symptomatic LSS.