Redundant nerve roots of the cauda equina in lumbar spinal canal stenosis, an MR study on 500 cases. Eur Spine J. 2015;24:2315-2320. [PMID: 26071946 DOI: 10.1007/s00586-015-4059-y]

Risk Factors for de Novo Postoperative Urinary Retention in Posterior Lumbar Spine Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

De novo postoperative urinary retention (POUR) after lumbar posterior decompression surgery for lumbar spinal canal stenosis (LSCS) is a statistically known but uncommon complication for both patients and spine surgeons. The aim of this study is to review clinical data and imaging findings and identify preoperative predictors of de novo POUR.

METHODS

The subjects were 738 surgically treated patients with LSCS, without preoperative bladder dysfunction or perioperative complications. Univariate and multivariate analyses using propensity score matching were performed to identify prognostic factors for POUR lasting for at least 1 week after postoperative urinary catheter removal.

RESULTS

POUR occurred in 23 patients (3.1%). The median recovery time was 41 days and only 12 patients (52.2%) showed improvement within 3 months. Patients with POUR were significantly older, and the lumbar Cobb angle, location of compressed dura mater (ventral or dorsal), and type of cauda equina redundancy (curve-type) were identified as independent prognostic factors. POUR had no association with sex, comorbidities, surgical procedures, number of decompressed segments, or degree of dura mater compression.

CONCLUSIONS

This study suggests that older age and curve-type stenosis with ventral or dorsal compression of the dura mater are risk factors for development of de novo POUR. Such preoperative imaging findings may indicate a higher risk of intraoperative thermal and nerve injuries, and possible uneven cauda equina flow improvement after decompression.

Redundant nerve roots on magnetic resonance imaging can predict ongoing denervation in patients with lumbar spinal stenosis

INTRODUCTION/AIMS

Redundant nerve roots (RNRs) are abnormally elongated and tortuous nerve roots that develop secondary to degenerative spinal stenosis. RNRs have been associated with poorer clinical outcomes after decompression surgery; however, studies on their clinical characteristics are limited. This study aimed to investigate the association between RNRs and denervation potentials, that is, abnormal spontaneous activity (ASA), on electromyography.

METHODS

We retrospectively reviewed data of patients who underwent an electrodiagnostic study of the lower extremities between January 2020 and March 2023. Of these, patients with lumbar central spinal stenosis, as seen on magnetic resonance imaging, were included. We analyzed clinical and imaging data, including presence of ASA, and compared them according to the presence of RNRs. Multivariable logistic regression analysis was employed to identify factors associated with development of ASA.

RESULTS

Among the 2003 patients screened, 193 were included in the study. RNRs were associated with advanced age (p < .001), longer symptom duration (p = .009), smaller cross-sectional area of the dural sac at the stenotic level (p < .001), and higher frequency of ASA (p < .001). Higher probability of ASA was correlated with greater RNR severity (p < .001). In the multivariable logistic regression analysis, ASA occurrence was associated with smaller cross-sectional area, multiple stenotic sites, and severe-grade RNRs.

DISCUSSION

The presence of RNRs, particularly severe-grade RNRs, was identified as a significant risk factor for the development of ASA on electromyography. This finding may aid physicians in estimating the prognosis of patients with central spinal stenosis.

MRI parameters predict central lumbar spinal stenosis combined with redundant nerve roots: a prospective MRI study

Background

To observe changes in the cauda equina nerve on lumbar MRI in patients with central lumbar spinal stenosis (LSS).

Methods

878 patients diagnosed with LSS by clinical and MRI were divided into the redundant group (204 patients) and the nonredundant group (674 patients) according to the presence or absence of redundant nerve roots (RNRs). The anteroposterior diameter of the spinal canal (APDS) and the presence of multiple level stenosis, disc herniation, thickening of ligamentum flavum (LF) and increased epidural fat were assessed on MRI. Univariate and multivariate logistic regression analyses were performed to explore the predictors of LSS combined with RNRs.

Results

Patients with LSS combined with RNRs had thicker epidural fat, smaller APDS and more combined multifaceted stenosis. Female patients and older LSS patients were more likely to develop RNRs; there was no difference between two groups in terms of disc herniation (p > 0. 05). Age, APDS, multiple level stenosis, and increased epidural fat were significantly correlated with the formation of LSS combined with RNRs (p < 0.05).

Conclusion

A smaller APDS and the presence of multiple level stenosis, thickening of LF, and increased epidural fat may be manifestations of anatomical differences in patients with LSS combined with RNRs. Age, APDS, multiple level stenosis, and increased epidural fat play important roles. The lumbar spine was measured and its anatomy was observed using multiple methods, and cauda equina changes were assessed to identify the best anatomical predictors and provide new therapeutic strategies for the management of LSS combined with RNRs.

Redundant nerve roots indicate higher degree of stenosis in lumbar spine stenotic patients

OBJECTIVES

Redundant Nerve Root (RNR) is a tortuous and elongated radiological appearance of cauda equina on Magnetic Resonance Imaging (MRI) in Lumbar Spinal Canal Stenosis (LSCS) patients. This study evaluated preoperative spinal morphometry associated with the development of RNR.

METHODS

The retrospective cohort was conducted at The Aga Khan University Hospital, and included patients undergoing decompressive spinal surgery secondary to degenerative LSCS in 2015. The patients were divided into two groups with respect to the presence of preoperative RNR. Spinal morphometry was defined by several radiological parameters, including areas of dural sac (DSA), spinal canal, spinal foramen, facets, and spinal joints, and bilateral angles based on vertebral anatomy.

RESULTS

A total of 55 patients were enrolled with a mean age of 57.1 years, in which 22 (40%) expressed RNR in their MRI. The RNR group had significantly lower mean DSA (59.64 vs 84.01 mm2; p = 0.028), bilateral posterior facet angle (Right: 33.84 vs 46.21, p = 0.004; Left: 36.43 vs 43.80, p = 0.039) and higher bilateral anterior facet angles (Right: 54.85 vs 44.57, p = 0.026; Left: 55.27 vs 46.36, p = 0.050) compared to the non-RNR group. The other bidimensional and angular parameters did not observe any statistical difference between the two groups.

CONCLUSION

RNR was associated with a higher degree of stenosis in patients with LSCS. Bilateral anterior and posterior facets angles contribute to its development, indicating particular spinal morphology to be vulnerable to the stenotic disease.

Relationship between lumbar spinal stenosis and cauda equina movement during the Valsalva maneuver

OBJECTIVE

To confirm the relationship between lumbar spinal stenosis (LSS) and cauda equina movement during the Valsalva maneuver.

MATERIALS AND METHODS

Two radiologists at our institution independently evaluated cauda equina movement on pelvic cine MRI, which was performed for urethrorrhea after prostatectomy or pelvic prolapse in 105 patients (99 males; mean age: 69.0 [range: 50-78] years), who also underwent abdominopelvic CT within 2 years before or after the MRI. The qualitative assessment of the cine MRI involved subjective determination of the cauda equina movement type (non-movement, flutter, and inchworm-manner). The severity of LSS on abdominopelvic CT was quantified using our LSS scoring system and performed between L1/2 and L5/S1. We calculated the average LSS scores of two analysts and extracted the worst scores among all levels.

RESULTS

Cauda equina movement was observed in 15 patients (14%), inchworm-manner in 10 patients, and flutter in five patients. Participants with cauda equina movement demonstrated significantly higher LSS scores than those without movement (P < 0.001, Wilcoxon's rank-sum test). A significant difference was observed in the worst LSS scores between participants without movement and those with inchworm-manner movement (P < 0.001, Bonferroni's corrected). There were no significant differences between participants without movement and those with flutter movement (P = 0.3156) and between participants with flutter movement and those with inchworm-manner movement (P = 0.4843).

CONCLUSION

Cauda equina movement in cine MRI during the Valsalva maneuver is occasionally observed in patients with severe LSS, and may be associated with pathogenesis of redundant nerve roots.

The serpentine pattern on MRI as an early prognostic factor after fusion for lumbar spinal stenosis

This study aimed to determine the relationship between the serpentine pattern nerve roots (SNR) and prognosis after lumbar fusion for lumbar spinal stenosis (LSS) by comparing clinical outcomes in patients with or without a serpentine pattern. LSS patients with neurological symptoms often present with SNRs. Several studies have shown that LLS symptoms are worse in patients with SNRs. However, the relationship between SNR and outcome after spinal fusion surgery has not yet been established. A total of 332 patients who underwent spinal fusion surgery between January 1, 2010, and December 31, 2019, were enrolled. Patients were divided into those with a serpentine pattern (S group) and those without a serpentine pattern (N group). The prognosis of the 2 groups was compared using visual analog scale (VAS), Oswestry disability index, claudication distance, medication dose for leg dysesthesia, and glucose tolerance. A total of 113 patients had a serpentine pattern, while the remaining 219 did not. Symptom duration and presence of diabetes mellitus were significantly different between the 2 groups (N = 25.4, S = 32.6, P < .05). Changes in the VAS score for lower extremity pain between the 2 groups at 1 year after surgery showed that patients without a serpentine pattern had significantly better outcomes than those with a serpentine pattern (N: 2.7 ± 1.1 vs S: 4.1 ± 1.3; P < .001), despite the score change at 1 month showing no difference (N: 3.5 ± 0.9 vs S: 3.8 ± 1.0; P = .09). SNRs on MRI are more prevalent in diabetic patients and are a negative prognostic factor in lumbar fusion surgery for LSS. Our insights may help physicians decide the optimal surgical plan and predict the postoperative prognosis of patients with LSS.

The prevalence of redundant nerve roots in standing positional MRI decreases by half in supine and almost to zero in flexed seated position: a retrospective cross-sectional cohort study

PURPOSE

This retrospective cross-sectional cohort study investigated the influence of posture on lordosis (LL), length of the spinal canal (LSC), anteroposterior diameter (APD L1-L5), dural cross-sectional area (DCSA) of the lumbar spinal canal, and the prevalence of redundant nerve roots (RNR) using positional magnetic resonance imaging (MRI) (0.6 T).

METHODS

Sixty-eight patients with single-level degenerative central lumbar spinal stenosis (cLSS) presenting with RNR in the standing position (STA) were also investigated in supine (SUP) or neutral seated (SIT) and flexed seated (FLEX) positions. Additionally, 45 patients complaining of back pain and without MRI evidence of LSS were evaluated. Statistical significance was set at p < 0.05.

RESULTS

Controls (A) and patients with cLSS (B) were comparable in terms of mean age (p = 0.88) and sex (p = 0.22). The progressive transition from STA to FLEX led to a comparable decrease in LL (p = 0.97), an increase in LSC (p = 0.80), and an increase in APD L1-L5 (p = 0.78). The APD of the stenotic level increased disproportionally between the different postures, up to 67% in FLEX compared to 29% in adjacent non-stenotic levels (p < 0.001). Therefore, the prevalence of RNR decreased to 49, 26, and 4% in SUP, SIT, and FLEX, respectively.

CONCLUSION

The prevalence of RNR in standing position was underestimated by half in supine position. Body postures modified LL, LSC, and APD similarly in patients and controls. Stenotic levels compensated for insufficient intraspinal volume with a disproportionate enlargement when switching from the STA to FLEX.

Spinal Radiology associated with Redundant Nerve Roots of cauda equina in lumbar spine stenosis

OBJECTIVES

Redundant Nerve Roots (RNR) is a common radiological observation of elongated tortuous appearance of cauda equina nerve roots in sagittal MRI. It is considered a poor prognostic factor, but the associated spinal morphometry remains unfamiliar.

METHODS

A retrospective cohort study was conducted at the Aga Khan University Hospital, Pakistan. Patients, aged 18 or above, undergoing decompressive spinal surgery due to degenerative Lumbar Spinal Canal Stenosis (LSCS) in 2015 were included. Patients were divided in groups as per presence of RNR and assessed for spinal morphometric parameters.

RESULTS

Fifty-two patients, aged 57.52 ± 12.08 years, were enrolled in the study. The patients in RNR group were older than those in non-RNR group (p = 0.023). RNR was significantly associated with sedimentation sign (15 vs 11; p = 0.011), as well as L2/L3 (12 vs 9; p = 0.043) and L3/L4 (18 vs 18; p = 0.034) stenosis. Ligamentum flavum hypertrophy at the most stenotic level was more common in the RNR group (20 vs 19; p = 0.006). The only quantitative parameter statistically associated with RNR was lower ligamentous interfacet distance (5.07 ± 1.95 vs 8.07 ± 4.26 mm; p = 0.010). All other parameters did not contribute to the development of RNR in LSCS patients. The multivariate model revealed significant contribution of age, male sex, ligamentous interfacet distance and disc bulge to develop RNR.

CONCLUSION

Certain spinal morphometric parameters contribute towards RNR formation, which represents higher degree of spinal stenosis. These parameters, along with RNR, should be regularly reported for preoperative consideration of LSCS management.

Clinical Significance of Redundant Nerve Roots in Patients with Lumbar Stenosis Undergoing Minimally Invasive Tubular Decompression

OBJECTIVE

Symptomatic lumbar spinal stenosis (LSS) is a common indication for surgery in the elderly. Preoperative radiographic evaluation of patients with LSS often reveals redundant nerve roots (RNRs). The clinical significance of RNRs is uncertain. RNRs have not been studied in the setting of minimally invasive surgery. This study investigates the relationship between RNRs and clinical outcomes after minimally invasive tubular decompression.

METHODS

Chart review was performed for patients with degenerative LSS who underwent minimally invasive decompression. Preoperative magnetic resonance imaging parameters were assessed, and patient-reported outcomes were analyzed.

RESULTS

Fifty-four patients underwent surgery performed at an average of 1.8 ± 0.8 spinal levels. Thirty-one patients (57%) had RNRs. Patients with RNRs were older (median = 72 years vs. 66 years, P = 0.050), had longer median symptom duration (32 months vs. 15 months, P < 0.01), and had more levels operated on (2.1 vs. 1.4; P < 0.01). The median follow-up after surgery was 2 months (range = 1.3-12 months). Preoperative and postoperative patient-reported outcomes were similar based on RNR presence. Patients without RNRs had larger lumbar cross-sectional areas (CSAs) (median = 121 mm² vs. 95 mm², P = 0.014) and the index-level CSA (52 mm² vs. 34 mm², P = 0.007). The CSA was not correlated with RNR morphology or location.

CONCLUSIONS

Preoperative RNRs are associated with increased age, symptom duration, and lumbar stenosis severity. Patients improved after minimally invasive decompression regardless of RNR presence. RNR presence had no effect on short-term clinical outcomes. Further study is required to assess their long-term significance.

Plexiform neurofibroma of the cauda equina with follow-up of 10 years: A case report

BACKGROUND

Plexiform neurofibromas are extremely rarely found in the region of cauda equina and can pose a significant challenge in the diagnostic and management sense. To our knowledge, only 7 cases of cauda equina neurofibromatosis (CENF) have been reported up-to-date.

CASE SUMMARY

We describe a case of a 55-year-old man with a 10 years history of progressive lower extremities weakness and bladder dysfunction. Before presenting, patient was misdiagnosed with idiopathic polyneuropathy. Lumbar spine MRI revealed a tortuous tumorous masses in the cauda equina region, extending through the Th12-L4 vertebrae. The patient underwent Th12-L3 Laminectomy with duraplasty. During the operation, the most enlarged electroneurographically silent nerve root was resected, anticipating inadequate decompression if nerve root was spared. The patient’s neurological condition improved post-operatively, but urinary retention became the major complaint. We provide a follow-up period of 10 years. During this time, the patient’s condition progressively worsened despite extensive decompression. The consequent MRI scans showed progressive enlargement of cauda equina roots and increasing lumbar stenosis, predominantly affecting L3-L4 segment. During the follow-up 8 years after the operation, the patient complained of worsening lower extremities sensorimotor function and neurogenic claudication. Subsequent MRI revealed lumbar spine stenosis at the level of L3-L4, requiring further decompression. The patient underwent a second surgery involving L4-L5 Laminectomy with duraplasty and L2-L5 transpedicular fixation. The post-operative period was uneventful. Latest follow-up 18 mo after the second surgery revealed substantial improvement in patient’s well-being.

CONCLUSION

CENF should be kept in mind during the differential diagnostic work-up for polyneuropathies. Management with an extensive decompression, duraplasty and primary spinal fixation represents a rational approach to achieve a sustained symptomatic improvement and superior overall outcome.

Redundant Nerve Roots of the Cauda Equina, MRI Findings and Postoperative Clinical Outcome: Emphasizing an Overlooked Entity

STUDY DESIGN

Retrospective study.

OBJECTIVE

To describe the MRI findings of RNRs in patients with low back pain, and observe the imaging findings and the clinical outcome post decompression surgery.

METHODS

The lumbar spine MRI of 202 patients (122 females) with proven RNRs were retrospectively reviewed. The morphology and the location of the RNRs in relation to the level of stenosis were described. The level(s), grade and cause of lumbar canal stenosis were recorded. The persistence of symptoms and the imaging findings on follow up post decompression surgery were recorded. The imaging findings were correlated among each other and with patients' demographics.

RESULTS

Two distinctive morphological appearance of the RNRs were noted: loop (56.4%), and serpentine-shaped. In the majority of the cases the RNRs were located above the level of stenosis (79.7%). Eighteen patients underwent decompression surgery, only 4 patients remained symptomatic post decompression surgery. The RNRs changed in shape and location after decompression surgery. Age was a strong predictor value in the location of the RNRs. There was no correlation between the shape and location of the RNRs, or with the gender of the patients.

CONCLUSION

RNRs is not an uncommon finding on lumbar spine MRI with lumbar canal stenosis. Its importance remains a controversy. A common language between the radiologists and the clinicians is mandatory to aid in the management planning.

Role of redundant nerve roots in clinical manifestations of lumbar spine stenosis

Background

Redundant nerve roots (RNRs) are defined as elongated, thickened, and tortious appearing roots of the cauda equina secondary to lumbar spinal canal stenosis (LSCS). The study compared the clinical and radiological features of patients with LSCS with versus without RNR.

Methods

This retrospective study was performed on 55 patients who underwent decompressive surgery for degenerative LSCS. Patients were divided into two groups based on the presence of RNR in their preoperative magnetic resonance imaging, as evaluated by a radiologist blinded to the study design. Medical records were reviewed for basic demographic, clinical MR presentation, and outcomes utilizing Japanese Orthopaedic Association (JOA) scores.

Results

The mean age of enrolled patients was 57.1, with mean follow-up of 4.0 months. RNR was found in 22 (40%) of patients with LSCS. These patients were older than those patients without RNR (62.2 vs. 53.7). Interestingly, there were no statistically significant differences in clinical presentations, duration of symptoms, and outcomes using JOA scores between the two groups.

Conclusion

RNR is a relatively common radiological finding (i.e., 40%) in patients with LSCS. It is more likely to be observed in older patients. However, no significant differences were noted in clinical presentation and functional outcomes with respect to the presence or absence of RNR.

Magnetic resonance imaging findings of redundant nerve roots of the cauda equina

BACKGROUND

Redundant nerve roots (RNRs) of the cauda equina are often a natural evolutionary part of lumbar spinal canal stenosis secondary to degenerative processes characterized by elongated, enlarged, and tortuous nerve roots in the superior and/or inferior of the stenotic segment. Although magnetic resonance imaging (MRI) findings have been defined more frequently in recent years, this condition has been relatively under-recognized in radiological practice. In this study, lumbar MRI findings of RNRs of the cauda equina were evaluated in spinal stenosis patients.

AIM

To evaluate RNRs of the cauda equina in spinal stenosis patients.

METHODS

One-hundred and thirty-one patients who underwent lumbar MRI and were found to have spinal stenosis between March 2010 and February 2019 were included in the study. On axial T2-weighted images (T2WI), the cross-sectional area (CSA) of the dural sac was measured at L2-3, L3-4, L4-5, and L5-S1 levels in the axial plane. CSA levels below 100 mm² were considered stenosis. Elongation, expansion, and tortuosity in cauda equina fibers in the superior and/or inferior of the stenotic segment were evaluated as RNRs. The patients were divided into two groups: Those with RNRs and those without RNRs. The CSA cut-off value resulting in RNRs of cauda equina was calculated. Relative length (RL) of RNRs was calculated by dividing the length of RNRs at mid-sagittal T2WI by the height of the vertebral body superior to the stenosis level. The associations of CSA leading to RNRs with RL, disc herniation type, and spondylolisthesis were evaluated.

RESULTS

Fifty-five patients (42%) with spinal stenosis had RNRs of the cauda equina. The average CSA was 40.99 ± 12.76 mm² in patients with RNRs of the cauda equina and 66.83 ± 19.32 mm² in patients without RNRs. A significant difference was found between the two groups for CSA values (P < 0.001). Using a cut-off value of 55.22 mm² for RNRs of the cauda equina, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) values of 96.4%, 96.1%, 89.4%, and 98.7% were obtained, respectively. RL was 3.39 ± 1.31 (range: 0.93-6.01). When the extension of RNRs into the superior and/or inferior of the spinal canal stenosis level was evaluated, it was superior in 54.5%, both superior and inferior in 32.8%, and inferior in 12.7%. At stenosis levels leading to RNRs of the cauda equina, 29 disc herniations with soft margins and 26 with sharp margins were detected. Disc herniation type and spondylolisthesis had no significant relationship with RL or CSA of the dural sac with stenotic levels (P > 0.05). As the CSA of the dural sac decreased, the incidence of RNRs observed at the superior of the stenosis level increased (P < 0.001).

CONCLUSION

RNRs of the cauda equina are frequently observed in patients with spinal stenosis. When the CSA of the dural sac is < 55 mm², lumbar MRIs should be carefully examined for this condition.

Biomechanical influences of gait patterns on knee joint: Kinematic & EMG analysis

Background

As lumbar spinal stenosis commonly occurs between the L2 and L5 segments, hip abductors are easily affected. However, studies regarding the gait pattern in these patients from the coronal plane have not yet been conducted.

Purpose

To determine the effects of lumbar spinal stenosis on the gait pattern (stride width and femorotibial angle) and hip abductor surface electromyography in varied stride widths compared with healthy individuals.

Study design

Prospective case-control study.

Methods

Seventeen patients and 20 healthy individuals were enrolled. Each participant completed three gait assessments in their normal gait, adducted gait and abducted gait. The femorotibial angle and surface electromyography signals were measured. Pain scores was used to quantify the degree of discomfort in the gluteal area and medial side of the knee.

Results

When the hip abductors’ surface electromyography signals were normalized by quadriceps femoris, patients group showed significantly higher activation ratios throughout all gait patterns. Generally, surface electromyography signals and ratios were significantly higher during abducted gait compared with a normal gait. Femorotibial angle became significantly closer to the varus in healthy individuals during abducted gait. When femorotibial angle during normal gait was compared between the two groups, patients group exhibited slightly wider stride width and FTA significantly closer to the varus. Pain scores were significantly higher in the patient group and during abducted gait.

Conclusion

Wider stride widths indicated increased relative activation of the hip abductors, closer proximity between femorotibial angle and varus, and increased pain scores for discomfort. The same tendency was observed in patients group when compared with healthy individuals. Widening of stride width in patients group despite abductor weakness suggests that additional muscle recruitment may be needed to maintain balance. Furthermore, such a distinctive gait pattern exerts increased loading on the medial knee, relating to the escalated risk of degenerative knee osteoarthritis.

The prevalence of redundant nerve roots in patients with lumbar spinal stenosis is body position dependent: a retrospective observational study with repeated measures design in an upright MRI scanner

Purpose

Redundant nerve roots (RNRs) are a negative prognostic factor in patients with central lumbar spinal stenosis (LSS). Forty percent of candidates for surgical decompression show RNRs (RNR+) on preoperative conventional magnetic resonance imaging (MRI). We investigated the prevalence of RNRs in three functional postures (standing, neutral sitting and flexed sitting) with an upright MRI (upMRI).

Methods

A retrospective observational study with a repeated measures design. Thirty surgical candidates underwent upMRI. Sagittal and axial T2-weighted images of the three functional postures were evaluated. The segmental length of the lumbar spine (sLLS), the lordotic angle (LA) and the dural cross-sectional area (DCSA) were measured in each body position. Generalized linear mixed models were carried out. The 0.05 level of probability was set as the criterion for statistical significance.

Results

The prevalence of RNRs decreased from 80% during standing to 16.7% during flexed sitting (p < 0.001). The sLLS increased significantly from standing to neutral sitting in both RNR groups (p < 0.001). The increase from neutral sitting to flexed sitting was only significant (p < 0.001) for the group without RNRs (RNR−). The LA decreased significantly for both RNR groups from standing to flexed sitting (p < 0.001). The DSCA increased significantly in the RNR− group (p < 0.001) but not in the RNR+ group (p = 0.9).

Conclusion

The prevalence of RNRs is body position dependent. Increases in DCSA play a determinant role in resolving RNRs.

Electrodiagnostic characteristics of upper lumbar stenosis: Discrepancy between neurological and structural levels

BACKGROUND

Radiculopathies caused by spinal stenosis in the upper lumbar spinal canal (L1/2, L2/3, L3/4) have not been comprehensively investigated.

METHODS

This retrospective study reviewed 14 patients from a tertiary hospital outpatient clinic. The inclusion criteria were upper lumbar stenosis seen on MRI and radiculopathies with active denervation confirmed on electromyography. Patients with any other conditions that could explain the clinical or electrophysiological manifestations were excluded.

RESULTS

Neurogenic findings were predominantly observed in L5 or S1 myotomes on electromyography. Abnormal spontaneous activity was observed in distal muscles in all patients and in proximal muscles in eight patients. Axonal involvement was bilateral in 10 patients and unilaterally in 4 patients. MRI showed redundant nerve roots in 13 patients with chronic reinnervation on electromyography.

CONCLUSIONS

Upper lumbar spinal stenosis usually causes L5 or S1 radiculopathies with diverse patterns. This discrepancy may cause diagnostic confusion.

Redundant nerve roots in lumbar spinal stenosis: inter- and intra-rater reliability of an MRI-based classification

Purpose

Patients with central lumbar spinal stenosis (LSS) have a longer symptom history, more severe stenosis, and worse postoperative outcomes, when redundant nerve roots (RNRs) are evident in the preoperative MRI. The objective was to test the inter- and intra-rater reliability of an MRI-based classification for RNR.

Methods

This is a retrospective reliability study. A neuroradiologist, an orthopedic surgeon, a neurosurgeon, and three orthopedic surgeons in-training classified RNR on 126 preoperative MRIs of patients with LSS admitted for microsurgical decompression. On sagittal and axial T2-weighted images, the following four categories were classified: allocation (A) of the key stenotic level, shape (S), extension (E), and direction (D) of the RNR. A second read with cases ordered differently was performed 4 weeks later. Fleiss and Cohen’s kappa procedures were used to determine reliability.

Results

The allocation, shape, extension, and direction (ASED) classification showed moderate to almost perfect inter-rater reliability, with kappa values (95% CI) of 0.86 (0.83, 0.90), 0.62 (0.57, 0.66), 0.56 (0.51, 0.60), and 0.66 (0.63, 0.70) for allocation, shape, extension, and direction, respectively. Intra-rater reliability was almost perfect, with kappa values of 0.90 (0.88, 0.92), 0.86 (0.84, 0.88), and 0.84 (0.81, 0.87) for shape, extension, and direction, respectively. Intra-rater kappa values were similar for junior and senior raters. Kappa values for inter-rater reliability were similar between the first and second reads (p = 0.06) among junior raters and improved among senior raters (p = 0.008).

Conclusions

The MRI-based classification of RNR showed moderate-to-almost perfect inter-rater and almost perfect intra-rater reliability.

Patient demographics and MRI-based measurements predict redundant nerve roots in lumbar spinal stenosis: a retrospective database cohort comparison

Background

Up to 40% of patients diagnosed with lumbar spinal stenosis (LSS) show evidence of redundant nerve roots (RNR) of the cauda equina on their magnetic resonance images (MRI). The etiology of RNR is still unclear. Preoperative evidence of RNR is associated with a worse postsurgical outcome. Consequently, potential predictors of RNR could have a prognostic value. The aim was to test whether patient demographics and MRI-based measurements can predict RNR in LSS patients.

Methods

In a retrospective database-based cohort study the preoperative data of 300 patients, 150 with (RNR+) and 150 without (RNR-) evidence of RNR on their MRI were analyzed. Three independent researchers performed the MRI reads. Potential predictors were age, gender, body height (BH), length of lumbar spine (LLS), segmental length of lumbar spine (SLLS), lumbar spine alignment deviation (LSAD), relative LLS (rLLS), relative SLLS (rSLLS), number of stenotic levels (LSS-level), and grade of LSS severity (LLS-grade, increasing from A to D). Binomial logistic regression models were performed.

Results

RNR+ patients were 2.6 years older (p = 0.01). Weak RNR+ predictors were a two-years age increase (OR 1.06; p = 0.02), 3 cm BH decrease (OR 1.09; p = 0.01) and a 5 mm SLLS decrease (OR 1.34; p < 0.001). Strong RNR+ predictors were a 1% rLLS decrease (OR 2.17; p < 0.001), LSS-level ≥ 2 (OR 2.59; p = 0.001), LLS-grade C (OR 5.86; p = 0.02) and LLS-grade D (OR 18.4; p < 0.001). The mean rSLLS of RNR+ patients was 0.6% shorter (p < 0.001; 95% C.I. 0.4 to 0.8) indicating a disproportionate shorter lumbar spine.

Conclusions

We identified LSS severity grade and LSS levels as the strongest predictors of RNR. In addition to previous studies, we conclude that a shortened lumbar spine by degeneration is involved in the development of RNR.

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.

Degenerative lumbar spinal canal stenosis: intra- and inter-reader agreement for magnetic resonance imaging parameters

PURPOSE

To assess the inter- and intra-reader agreement of commonly used quantitative and qualitative image parameters for the assessment of degenerative lumbar spinal canal stenosis (LSS) by magnetic resonance imaging (MRI).

METHODS

In this ethical board approved cross-sectional multicenter study, MRI of 100 randomly selected patients (median age 72.5 years, 48 % female) of the prospective Lumbar Stenosis Outcome Study (LSOS) were evaluated by two independent readers. A set of five previously published core imaging parameters as well as nine qualitative and five quantitative additional parameters regarding LSS and degenerative changes of the lumbar spine were assessed to calculate κ and intraclass correlation coefficients (ICC) for the inter-reader agreement. Additional repeated image evaluations were performed by one reader to calculate the intra-reader agreement.

RESULTS

κ values for the core image parameters ranged between 0.42 (compromise of the foraminal zone) and 0.77 (relation between fluid and cauda equina) for inter-reader agreement and between 0.59 (compromise of the foraminal zone) and 0.8 (compromise of the central zone) for intra-reader agreement. The inter-reader agreement for the non-core parameters showed κ values of 0.27-0.69 and ICC values of 0.46-0.85. The intra-reader agreement showed κ values of 0.53-0.69 and ICC values of 0.81-0.88.

CONCLUSIONS

The inter- and intra-reader agreement of commonly used quantitative and qualitative image parameters for the assessment of LSS showed quite a variability with previously defined core parameters having good to excellent inter- and intra-reader agreements.