Vulnerability of the L5 nerve root during anterior lumbar interbody fusion at L5-S1: case series and review of the literature

OBJECTIVE

Nerve root injuries associated with anterior lumbar interbody fusion (ALIF) are uncommonly reported in the literature. This case series and review aims to describe the etiology of L5 nerve root injury following ALIF at L5-S1.

METHODS

The authors performed a single-center retrospective review of prospectively collected data of patients who underwent surgery between 2017 and 2019 who had postoperative L5 nerve root injuries after stand-alone L5-S1 ALIF. They also reviewed the literature with regard to nerve root injuries after ALIF procedures.

RESULTS

The authors report on 3 patients with postoperative L5 radiculopathy. All 3 patients had pain that improved. Two of the 3 patients had a neurological deficit, one of which improved.

CONCLUSIONS

Stretch neuropraxia from overdistraction is an important cause of postoperative L5 radiculopathy after L5-S1 ALIF. Judicious use of implants and careful preoperative planning to determine optimal implant sizes are paramount.

Full-Endoscopic Lumbar Decompression with Minimal Nerve Root Retraction for Impending Neurologic Deficit in Degenerative Lumbar Spine Diseases

OBJECTIVES

 The aim of this retrospective case study was to analyze the outcomes of minimal nerve root retraction in patients with impending neurologic deficit in degenerative lumbar spine disease using the full-endoscopic spine surgery.

MATERIALS AND METHODS

 Thirty-seven consecutive patients with impending neurologic deficit underwent endoscopic spine surgery through either the transforaminal or the interlaminar approach. Their clinical outcomes were evaluated with visual analog scale (VAS) leg pain score, Oswestry Disability Index (ODI), and MacNab's criteria. The outcome of motor deficitis was evaluated with the Medical Research Council (MRC) grade. Completeness of decompression was documented with a postoperative magnetic resonance imaging (MRI) and computed tomography (CT) scan.

RESULTS

 A total of 40 lumbar levels of 37 patients were operated, VAS score of the leg improved from 7.7 ± 1 to 1.9 ± 0.6 (p < 0.0001). ODI score improved from 74.7 ± 6.5 to 25.4 ± 3.49 (p < 0.0001). Motor weakness improved significantly immediately after surgery. The mean MRC grade increased to 1.97, 3.65, 4.41, and 4.76 preoperatively, at 1 week, at 3 months, and at the final follow-up, respectively, and all the patients with foot drop and cauda equina syndrome symptom recovered completely. One patient with great toe drop recovered partially to MRC grade 3. Mean follow-up of the study was 13.3 ± 6.1 months. According to MacNab's criteria, 30 patients (80.1%) had good and 7 patients (18.9%) had excellent results. Three patients required revision surgery.

CONCLUSIONS

 Minimal nerve root retraction during full-endoscopic spine surgery is safe and effective for treatment of the impending neurologic deficit. We could achieve a thorough decompression of the affected nerve root with acceptable clinical outcome and minimal postoperative morbidity.

Bleomycin induces fibrotic transformation of bone marrow stromal cells to treat height loss of intervertebral disc through the TGFβR1/Smad2/3 pathway

Background

Lower back pain is often accredited to loss of intervertebral disc (IVD) height and compromised spine stability as a result of intervertebral disc degeneration (IVDD). We aim to locally use bleomycin to induce the fibrotic transformation of bone marrow stromal cells (BMSCs) as a means to induce reparative fibrosis to slow down the height loss.

Methods

IVDs from patients were gathered for histological examination. The expression of the transforming growth factor beta 1 (TGF-β) signaling pathway was determined by qPCR and western blotting. Nucleus pulposus (NP) cells, annulus fibrosus (AF) cells, and the rats’ bone marrow stromal cells (BMSC) were cultured and their responsiveness to bleomycin was evaluated by Cell Counting Kit-8, comet assay, transwell migration, and wound healing assays. Rat IVDD models were created by puncture and rescued by bleomycin injection, and the effectiveness was evaluated by images (X-ray and MRI) and atomic force microscope.

Results

Histological examination showed increased levels of pro-fibrotic markers in IVDD tissues from patients. AF cells and BMSC cells were induced to adopt a pro-fibrotic phenotype with increased expression fibrotic markers Col1a1, Col3a1, and FSP1. The pro-fibrotic effect of bleomycin on AF cells and BMSCs was in part due to the activation of the TGFβ-TGFβR1-SMAD2/3 signaling pathway. Pharmacological inhibition or gene knock-down of TGFβR1 could mitigate the pro-fibrotic effects.

Conclusion

Locally, injection of bleomycin in rats’ IVD induced rapid fibrosis and maintained its height through the TGFβ-TGFβR1-SMAD2/3 signaling pathway.

Extradural and intradural characteristics of the cervical nerve root anomalies

The anomalous anatomical arrangement of the cervical spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. This work aimed to reveal intraspinal anatomical anomalies of the extradural and also intradural cervical spinal nerve roots courses. The anatomical study was realised in 43 cadavers with a mean age of 53.7 (32 men and 11 women). After opening the spinal canal and also the dural sac the intradural and extradural anomalies of the cervical spinal nerve roots (bilaterally) were explored and documented. We found completely 49 cases (56.98%) of intraspinal cervical nerve root anomalies. Extradural anomalies were found in 11 cases (12.79%) including atypical spacing, two roots exiting through one neuroforamen, extradural communications, aberrant root. Intradural anomalies observed in 28 cases (32.56%) comprised: communications between the dorsal roots and ventral roots separately or together and the multiple communications. Other anomalies (10 cases, 11.63%) included various types of atypical spacing of the roots and their asymmetry. All the results are differentiated according to the plexus type (pre-, postfixed, normotyped). This study describes intraspinal (extradural and intradural) anatomical anomalies of the cervical spinal nerve root courses. Knowledge of these variabilities should help to prevent the failure of several medical procedures.

Intraspinal characteristics of thoracic spinal nerve roots anomalies

Purpose: The anomalous anatomical arrangement of the thoracic spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. The aim of this work was to reveal intraspinal anatomical variations of the thoracic spinal nerve roots.Methods: Anatomical study on 43 cadavers with a mean age of 53.7. After opening the spinal canal and dural sac, intradural and extradural anomalies of the thoracic spinal nerve roots were documented. Extradural communicating branches were excised, histologically processed and examined for the presence of nervous tissue.Results: We found 14 cases (32.6%) of intraspinal thoracic nerve root variations: intradural in 8 cases (18.6%), intradural communicating branches in 3 cases (6.97%), extradural anatomical variations occurred 6 cases (13.95%), 2 cases (4.65%) had extradural communicating branches between the nerve roots, 1 case had simultaneous occurrence of intradural and extradural communications (0.23%). All the results are differentiated according to the plexus type. In macroscopic extradural thoracic communicating branch had no nervous tissue on microscopy.Conclusions: This study describes intraspinal anatomical variations of thoracic spinal nerve roots. Knowledge of these variables should help prevent the failure of several medical procedures.

The Relationship Between Lumbar Lateral Listhesis and Radiculopathy in Adult Scoliosis

STUDY DESIGN

Retrospective review and prospective validation study.

OBJECTIVE

To develop a classification system of lumbar lateral listhesis that suggests different likelihoods of having radiculopathy in adult scoliosis.

SUMMARY OF BACKGROUND DATA

The association of lumbar lateral listhesis with radiculopathy remains uncertain.

METHODS

A retrospective cohort of patients with adult scoliosis enrolled from 2011 to 2015 was studied to develop a classification system of lateral listhesis that can stratify the likelihood of having radiculopathy. Four radiological aspects of lateral listhesis, including Nash and Moe vertebral rotation, L4-L5 lateral listhesis, the number of consecutive listheses, and the presence of a contralateral lateral listhesis at the thoracolumbar junction above a caudal listhesis, were evaluated on radiographs. Their associations with the presence of radicular leg pain were evaluated using multivariable logistic regression. The classification system of lateral listhesis was thus developed using the most influential radiological factors and then validated in a prospective cohort from 2016 to 2017.

RESULTS

The retrospective cohort included 189 patients. Vertebral rotation is more than or equal to grade 2 (odds ratio [OR] = 9.45, 95% confidence interval [CI]: 4.07-25.14) and L4-5 listhesis (OR = 4.56, 95%CI: 1.85-12.35) were the two most influential listhesis factors associated with radiculopathy. The classification system of lateral listhesis was thus built based on the combinations of their respective presence: Type 0, 1, 2, 3 were defined as not having listhesis at all, none of the two factors present, one of the two presents, and both present, respectively. This classification significantly stratified the probability of radiculopathy, in both the retrospective cohort (0%, 6.4%, 33.8%, and 68.4% in Type 0, 1, 2, and 3, respectively; P < 0.001) and a prospective cohort of 105 patients (0%, 16.7%, 46.9%, and 72.7%; P < 0.001).

CONCLUSION

Lumbar lateral listhesis is associated with the presence of radiculopathy in adult scoliosis. Types 2 and 3 lateral listhesis on radiographs may alert surgeons treating patients with spinal deformity.

LEVEL OF EVIDENCE

2.

Controllable Risk Factors for Neurologic Complications in Posterior Lumbar Interbody Fusion as Revision Surgery

BACKGROUND

The main concern with revision lumbar surgery is the possibility of neurologic complications. This retrospective study was conducted to clarify the risk factors, especially the effects of nerve stretching, for postoperative neurologic complications in posterior lumbar interbody fusion (PLIF) without excessive nerve retraction by bilateral total facetectomy as revision surgery.

METHODS

Between 2005 and 2015, 50 consecutive patients underwent revision PLIF for recurrent stenosis or recurrent disc herniation. The patients were divided into two groups: patients with neurological complications (NC group) and patients without neurological complications (non-NC group). Radiological examinations to evaluate the magnitude of nerve stretching included the following pre- and postoperative plain radiograph measurements: anterolisthesis at flexion, intervertebral lordosis in the neutral position, and posterior disc height in the neutral position.

RESULTS

Sixteen patients (32%) had neurological complications. The decrease in intervertebral lordosis was significantly greater in the NC group than that in the non-NC group (0.8° vs. -1.5°, P<0.05). Distraction of the posterior disc height was significantly greater in the NC group than that in the non-NC group (5.0 mm vs. 2.6 mm, P < 0.01). Neurological complications were seen in all patients with a decrease in intervertebral lordosis >3° and distraction of the posterior disc height >3 mm.

CONCLUSIONS

Decreased intervertebral lordosis, and distraction of the posterior disc height, which can be controlled by surgeons, appear to be risk factors for neurological complications following revision PLIF. In revision PLIF, surgeons should create segmental lordosis without excessive disc height distraction.

Intraspinal intradural variations of nerve roots

PURPOSE

The aim of this work is to point out the intraspinal anatomical variations of nerve roots and their possible participation in radiculopathy.

METHODS

The anatomical study was performed in 33 cadavers. There were 25 male cadavers aged 30-75 years and 8 female cadavers aged 45-77 years, with a mean age of 46.5 years to 24 h from death. All intradural rami communicantes between nerve roots were excised and examined histologically for the presence or absence of nervous tissue. The type of the plexus was defined by subtracting from the root C2.

RESULTS

Findings of the normotype of plexus formation occurred in 24 cases (72.7%). Variations in its formation were observed in nine cases (27.3%). The prefixed type was observed in six cases (18.2%), postfixed type in three cases (9.1%). The formation of isolated prefixed or postfixed type of the brachial and lumbosacral plexus was not observed. Anatomical preparations revealed intradural variations in all cases of the lumbosacral plexus, 22 times (66.7%) in cases of cervical roots, and in the thoracic region seven times (21.2%). Variations occurred more frequently in variations of plexus formation.

CONCLUSIONS

This study allowed us to identify and describe unpublished intraspinal intradural anatomical variations of nerve roots, and their interrelationships throughout the spinal canal with their potential influence on the clinical picture. Anatomical preparations revealed a higher incidence of intraspinal intradural variations, particularly between sacral roots. Reliance of their incidence of the plexus type was observed.

Nerve root anomalies: making sense of a complicated literature

INTRODUCTION

Nerve root anomalies (NRAs) are a set of well-described congenital irregularities for which several classification systems have been devised over the years.

CONCLUSION

This comprehensive review examines the anatomy and characteristics of NRAs; their surgical, radiographic, and cadaveric prevalence rates; clinical and radiographic presentations; and surgical management. In addition, the top 5 NRA classification systems are presented and related.

Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

There is growing recognition of the kyphotic clivo-axial angle (CXA) as an index of risk of brainstem deformity and craniocervical instability. This review of literature and prospective pilot study is the first to address the potential correlation between correction of the pathological CXA and postoperative clinical outcome. The CXA is a useful sentinel to alert the radiologist and surgeon to the possibility of brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographically manifest as a kyphotic CXA, underwent correction of deformity (normalization of the CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessed preoperatively and at one, three, six, and twelve months after surgery, using established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, and Karnofsky Index. Parametric and non-parametric statistical tests were performed to correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screws adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinical metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinical improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Lumbosacral intrathecal nerve roots: an anatomical study

BACKGROUND

The lumbosacral intrathecal anatomy is complex because of the density of nerve roots in the cauda equina. Space-occupying lesions, including disc herniation, trauma and tumor, within the spinal canal may compromise the nerve roots, causing severe clinical syndromes. The goal of this study is to provide spinal surgeons with a detailed anatomical description of the intrathecal nerve roots and to emphasize their clinical importance.

METHOD

Ten formalin-fixed male cadavers were studied. They were dissected with the aid of a surgical microscope, and measurements were performed.

RESULTS

The number of dorsal and ventral roots ranged from one to three. The average diameter of roots increased from L1 to S1 (0.80 mm for L1 and 4.16 for S1), respectively. Then their diameter decreased from S1 to S5 (4.16 mm for S1, 0.46 mm for S5). The largest diameter was found at S1 and the smallest at S5. The average number of rootlets per nerve root increased from L1 to S1, then decreased (3.25 for L1, 12.6 for S1, and 1.2 for S5), respectively. The greatest rootlet number was seen at S1, and the fewest were observed at S5. The average diameter of the lateral recess gradually decreased from L1 to L4 (9.1 mm for L1; 5.96 mm for L4) and then increased at L5 level (6.06 mm); however, the diameter of the nerve root increased from L1 to L5. The midpoint of distance between the superior and inferior edge of the intradural exit nerve root was 3.47 mm below the inferior edge of the superior articular process at the L1 level, while the origin of the L5 exit root was 5.75 mm above the inferior edge. The root origin gradually ascended from L1 to L5.

CONCLUSIONS

The findings of this study may be valuable for understanding lesions compressing intradural nerve roots and may be useful for intradural spinal procedures.