Clinical anatomy and significance of the thoracic intervertebral foramen: A cadaveric study and review of the literature

Quantifying Lumbar Foraminal Volumetric Dimensions: Normative Data and Implications for Stenosis-Part 2 of a Comprehensive Series

INTRODUCTION

Lumbar foraminal stenosis (LFS) occurs primarily due to degenerative changes in older adults, affecting the spinal foramina and leading to nerve compression. Characterized by pain, numbness, and muscle weakness, LFS arises from structural changes in discs, joints, and ligaments, further complicated by factors like inflammation and spondylolisthesis. Diagnosis combines patient history, physical examination, and imaging, while management ranges from conservative treatment to surgical intervention, underscoring the need for a tailored approach.

MATERIALS AND METHODS

This multicenter study, conducted over six years at a tertiary hospital, analyzed the volumetric dimensions of lumbar foramina and their correlation with nerve structures in 500 patients without lumbar pathology. Utilizing high-resolution MRI with a standardized imaging protocol, eight experienced researchers independently reviewed the images for accurate measurements. The study emphasized quality control through the calibration of measurement tools, double data entry, validation checks, and comprehensive training for researchers. To ensure reliability, interobserver and intraobserver agreements were analyzed, with statistical significance determined by kappa statistics and the Student's t-test. Efforts to minimize bias included blinding observers to patient information and employing broad inclusion criteria to mitigate referral and selection biases. The methodology and findings aim to enhance the understanding of normal lumbar foramina anatomy and its implications for diagnosing and treating lumbar conditions.

RESULTS

The study's volumetric analysis of lumbar foramina in 500 patients showed a progressive increase in foraminal volume from the L1/L2 to the L5/S1 levels, with significant enlargement at L5/S1 indicating anatomical and biomechanical complexity in the lumbar spine. Lateral asymmetry suggested further exploration. High interobserver and intraobserver agreement levels (ICC values of 0.91 and 0.95, respectively) demonstrated the reliability and reproducibility of measurements. The patient cohort comprised 58% males and 42% females, highlighting a balanced gender distribution. These findings underscore the importance of understanding foraminal volume variations for lumbar spinal health and pathology.

CONCLUSION

Our study significantly advances spinal research by quantifying lumbar foraminal volumes, revealing a clear increase from the L1/L2 to the L5/S1 levels, indicative of the spine's adaptation to biomechanical stresses. This provides clinicians with a precise tool to differentiate between pathological narrowing and normal variations, enhancing the detection and treatment of lumbar foraminal stenosis. Despite limitations like its cross-sectional design, the strong agreement in measurements underscores the method's reliability, encouraging future research to further explore these findings' clinical implications.

The Impact of Posterior Intervertebral Osteophytes on Patient-Reported Outcome Measures After L5-S1 Anterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

(1) To develop a reliable grading system to assess the severity of posterior intervertebral osteophytes and (2) to investigate the impact of posterior intervertebral osteophytes on clinical outcomes after L5-S1 decompression and fusion through anterior lumbar interbody fusion (ALIF) and minimally-invasive transforaminal lumbar interbody fusion (MIS-TLIF).

BACKGROUND

There is limited evidence regarding the clinical implications of posterior lumbar vertebral body osteophytes for ALIF and MIS-TLIF surgeries and there are no established grading systems that define the severity of these posterior lumbar intervertebral osteophytes.

PATIENTS AND METHODS

A retrospective analysis of patients undergoing L5-S1 ALIF or MIS-TLIF was performed. Preoperative and postoperative patient-reported outcome measures of the Oswestry Disability Index (ODI) and leg Visual Analog Scale (VAS) at 2-week, 6-week, 12-week, and 6-month follow-up time points were assessed. Minimal clinically important difference (MCID) for ODI of 14.9 and VAS leg of 2.8 were utilized. Osteophyte grade was based on the ratio of osteophyte length to foraminal width. "High-grade" osteophytes were defined as a maximal osteophyte length >50% of the total foraminal width.

RESULTS

A total of 70 consecutive patients (32 ALIF and 38 MIS-TLIF) were included in the study. There were no significant differences between the two cohorts in patient-reported outcome measures or achievement of MCID for Leg VAS or ODI preoperatively or at any follow-ups. On multivariate analysis, neither the surgical approach nor the presence of high-grade foraminal osteophytes was associated with leg VAS or ODI scores at any follow-up time point. In addition, neither the surgical approach nor the presence of high-grade foraminal osteophytes was associated with the achievement of MCID for leg VAS or ODI at 6 months.

CONCLUSION

ALIF and MIS-TLIF are both valid options for treating degenerative spine conditions and lumbar radiculopathy, even in the presence of high-grade osteophytes that significantly occupy the intervertebral foramen.

LEVEL OF EVIDENCE

3.

A Modified Approach for Ultrasound-Guided Thoracic Paravertebral Block via Thoracic Intervertebral Foramen in an Adolescent Patient: A Case Report

This case report describes a modified approach for a thoracic paravertebral block by performing a bilateral ultrasound-assisted injection of 12 mL of 0.5% levobupivacaine near the thoracic intervertebral foramen, combined with general anesthesia, in a patient who underwent emergent laparotomy for small intestinal volvulus. Two continuous catheter sets were used for a bilateral continuous block with levobupivacaine 0.25% at a rate of 5–8 mL/h. No complications during the execution of the block were recorded. No supplemental opioids were administered and the patient was hemodynamically stable, requiring no pharmacological cardiovascular support during surgery. At the end of the surgical procedure, the patient received a continuous flow of 0.2% levobupivacaine as postoperative analgesia, at a basal flow of 4 mL/h per each side, a bolus of 4 mL, and a lockout time of 60 min was used. The postoperative pain on the Numeric Rating Scale was 2 at rest and it was 4 in motion, without neurological or respiratory sequelae due to block in the first 72 h after surgery.

The Complex Spine in Children with Spinal Muscular Atrophy: The Transforaminal Approach-A Transformative Technique

BACKGROUND AND PURPOSE

Spinal muscular atrophy, a genetic disease resulting in loss of motor function, presents from in utero to adulthood. Depending on progression and secondary scoliosis, spinal stabilization may be necessary. When planning intrathecal access in these patients, spinal anatomy is the most important factor. Therefore, when planning intrathecal nusinersen injections, we subdivided patients with spinal muscular atrophy into simple-versus-complex spine subgroups. Our purpose was to present our experience with our first 42 transforaminal intrathecal nusinersen injections.

MATERIALS AND METHODS

We reviewed 31 consecutive patients with spinal muscular atrophy types 1-3 who presented for intrathecal nusinersen injections from March 2017 to September 2018. Nine children had complex spines (ie, spinal instrumentation and/or fusion) and required preprocedural imaging for route planning for subarachnoid space access via transforaminal or cervical approaches.

RESULTS

A total of 164 intrathecal nusinersen injections were performed in 31 children 4-226 months of age, with 100% technical success in accessing the subarachnoid space. Nine patients with complex spinal anatomy underwent 45 intrathecal nusinersen injections; 42 of 45 procedures were performed via a transforaminal approach with the remaining 3 via cervical techniques. There were no complications.

CONCLUSIONS

Our initial experience has resulted in a protocol-driven approach based on simple or complex spinal anatomy. Patients with simple spines do not need preprocedural imaging or imaging-guided intrathecal nusinersen injections. In contrast, the complex spine subgroup requires preprocedural imaging for route planning and imaging guidance for therapy, with the primary approach being the transforaminal approach for intrathecal nusinersen injections.

[Not Available]

Objectives:

The objective of this study was to investigate the dimensions of the osseous lumbar intervertebral foramen (IVF) regarding a sample without any clinical indication of spine pathology and, additionally, survey possible correlations of these measurements with clinical characteristics of the individuals.

Materials and Methods:

CT images of spine-related asymptomatic individuals were examined on parasagittal and oblique projections for the evaluation of cranial foramen width (CrFW), caudal foramen width (CaFW), vertebral height (VH) and foraminal height (FH) in accordance with gender, age, height, weight, body mass index (BMI) and vertebral level.

Results:

Overall, CT images of 73 individuals, 40 men and 33 women, with mean age 56.81 (± 14.79) years, mean height 1.69 (± 0.09) meters, mean weight 81.27 (± 18.14) kilograms and mean BMI 28.35 (± 5.62) were included. The maximum mean FW was the CaFWL1 and the minimum the CrFWL5, with values of 8.11 and 6.01 mm, respectively. Height and weight were presented as significantly bigger in men than women; however, women had bigger lumbar IVF values and no significant width measurement for IVF was morphoobserved at any level for either sex. Age showed a negative impact on the elderly by reducing height and the majority of FW measurements. Statistically important differences in accordance with BMI were not seen.

Conclusions:

Data comparison with previous studies is ambiguous due to methodological differences and possible populational variations and they reveal just a glimpse of the in vivo lumbar IVF. Our data could have clinical application on lumbar spine interventions.

Transforaminal Percutaneous Endoscopic Discectomy using Transforaminal Endoscopic Spine System technique: Pitfalls that a beginner should avoid

Transforaminal Percutaneous Endoscopic Discectomy (TPED) is a minimally invasive technique mainly used for the treatment of lumbar disc herniation from a lateral approach. Performed under local anesthesia, TPED has been proven to be a safe and effective technique which has been also associated with shorter rehabilitation period, reduced blood loss, trauma, and scar tissue compared to conventional procedures. However, the procedure should be performed by a spine surgeon experienced in the specific technique and capable of recognizing or avoiding various challenging conditions. In this review, pitfalls that a novice surgeon has to be mindful of, are reported and analyzed.