Three-dimensional architecture of the neurovascular and adipose zones of the upper and lower lumbar intervertebral foramina: an epoxy sheet plastination study

Three-dimensional analysis of puncture needle path through safety triangle approach PLD and design of puncture positioning guide plate

OBJECTIVE

In this study, the three-dimensional relationship between the optimal puncture needle path and the lumbar spinous process was discussed using digital technology. Additionally, the positioning guide plate was designed and 3D printed in order to simulate the surgical puncture of specimens. This plate served as an important reference for the preoperative simulation and clinical application of percutaneous laser decompression (PLD).

METHOD

The CT data were imported into the Mimics program, the 3D model was rebuilt, the ideal puncture line N and the associated central axis M were developed, and the required data were measured. All of these steps were completed. A total of five adult specimens were chosen for CT scanning; the data were imported into the Mimics program; positioning guide plates were generated and 3D printed; a simulated surgical puncture of the specimens was carried out; an X-ray inspection was carried out; and an analysis of the puncture accuracy was carried out.

RESULTS

(1) The angle between line N and line M was 42°~55°, and the angles between the line M and 3D plane were 1°~2°, 5°~12°, and 78°~84°, respectively; (2) As the level of the lumbar intervertebral disc decreases, the distance from point to line and point to surface changes regularly; (3) The positioning guide was designed with the end of the lumbar spinous process and the posterior superior iliac spine on both sides as supporting points. (4) Five specimens were punctured 40 times by using the guide to simulate surgical puncture, and the success rate was 97.5%.

CONCLUSION

By analyzing the three-dimensional relationship between the optimal puncture needle path and the lumbar spinous process, the guide plate was designed to simulate surgical puncture, and the individualized safety positioning of percutaneous puncture was obtained.

Pro-Con Debate: Superior Versus Inferior Triangle Needle Placement in Transforaminal Epidural Injections

Although transforaminal epidural injections have long been used for radicular pain, there is no universal standard injection approach to the neural foramen. The intervertebral foramen and its surrounding structures comprise an anatomically sensitive area that includes bone and joint structures, the intervertebral disk, blood vessels (in particular, the radicular arteries), the epidural sheath, and the spinal nerve root. Given the relatively high risk of inadvertent injury or injection to these nearby structures, image guidance for transforaminal epidural steroid injections (TFESIs) is standard of care. However, there is a lack of consensus regarding the optimal approach to the neural foramen: from the traditional superior ("safe") triangle or from the inferior (Kambin's) triangle. In this Pro-Con commentary article, we discuss the relative advantages and disadvantages of each approach for TFESIs.

A Retrospective Comparative Study of Modified Percutaneous Endoscopic Transforaminal Discectomy and Open Lumbar Discectomy for Gluteal Pain Caused by Lumbar Disc Herniation

Introduction

This study aimed to demonstrate the safety and effectiveness of modified percutaneous endoscopic transforaminal discectomy (PETD) in the surgical management of single-segment lumbar disc herniation (LDH) gluteal pain and to determine whether it provides a better clinical outcome than open lumbar discectomy (OD).

Methods

A retrospective analysis of patients treated with modified PETD and OD for gluteal pain in LDH from January 2015 to December 2020 was conducted. Sample size was determined using a priori power analysis. Demographic information, surgical outcomes including procedure time (minutes), intraoperative blood loss (mL), hospital days, costs (RMB), fluoroscopy shots, recurrence and complications, etc., were recorded and analyzed. Prognostic outcomes were assessed using the visual analog scale (VAS), the Oswestry Disability Index (ODI), the Japanese Orthopedic Association Score (JOA) and modified MacNab criteria. The preoperative and postoperative VAS, ODI and JOA scores were recorded by two assistants. When the results were inconsistent, the scores were recorded again by the lead professor until all scores were consistently recorded in the data. MRI was used to assess radiological improvement and all patients received follow-ups for at least one year.

Results

The sample size required for the study was calculated by a priori analysis, and a total of 72 participants were required for the study to achieve 95% statistical test power. A total of 93 patients were included, 47 of whom underwent modified PETD, and 46 of whom underwent OD. In the modified PETD intragroup comparison, VAS scores ranged from 7.14 ± 0.89 preoperatively to 2.00 ± 0.58, 2.68 ± 0.70, 2.55 ± 0.69, 2.23 ± 0.81, and 1.85 ± 0.72 at 7 days, 1 month, 3 months, 6 months, and 12 months postoperatively. Patients showed significant pain relief postoperatively (P < 0.01). According to the modified MacNab score, the excellent rate in the PETD group was 89.36%. There was no significant difference compared to the OD group (89.13%, P > 0.05). Complication rates were lower (P > 0.05) but recurrence rates were higher (P > 0.05) in the modified PETD group than in the OD group. The modified PETD group had a faster operative time (P < 0.01), shorter hospital stay (P < 0.01), less intraoperative bleeding (P < 0.01), and less financial burden to the patient (P < 0.01) than the OD group. At 7 days postoperatively, the VAS score for low back pain was higher in the OD group than in the modified PETD group (P < 0.01). The VAS and JOA scores at 1, 3, 6, and 12 months postoperatively were not significantly different between the modified PETD and OD groups (P > 0.05), and the ODI was significantly different at 3 months postoperatively (P < 0.05).

Conclusion

Modified PETD treatment is safe and effective for gluteal pain due to L4/5 disc herniation and has the advantages of a lower complication rate, faster postoperative recovery, shorter length of stay, fewer anesthesia risks and lower cost of the procedure compared with OD. However, modified PETD has a higher recurrence rate.

Current and Future Applications of the Kambin’s Triangle in Lumbar Spine Surgery

Kambin’s triangle has become the anatomical location of choice when accessing the lumbar spine to treat degenerative spinal disorders. Currently, lumbar interbody fusion is the most common procedure utilizing this space; however, with the advent of the Kambin’s prism definition, advanced imaging modalities, and robotic-assisted techniques, lumbar spine surgery has become increasingly precise and less invasive. These technological and procedural advances have drastically reduced the rate of complications, improved patient outcomes, and expanded the use of the Kambin’s triangle to treat different pathologies utilizing cutting-edge techniques. In this review, the authors present the current uses of the Kambin’s triangle and the future application of this anatomical corridor in lumbar spine surgery.

Fine configuration of the dural fibrous network and the extradural neural axis compartment in the jugular foramen: an epoxy sheet plastination and confocal microscopy study

OBJECTIVE

The extradural neural axis compartment (EDNAC) is an adipovenous zone that is located between the meningeal (ML) and endosteal (EL) layers of the dura mater and has been minimally investigated in the jugular foramen (JF) region. In this study, the authors aimed to explore the fine architecture of the EDNAC within the JF and evaluate whether the EDNAC can be used as a component for JF compartmentalization.

METHODS

A total of 46 cadaveric heads (31 male, 15 female; age range 54-96 years) and 30 dry skulls were examined in this study. Twelve of 46 cadaveric heads were plastinated as a series of transverse (7 sets), coronal (3 sets), and sagittal (2 sets) slices and examined using stereomicroscopy and confocal microscopy. The dural entry points of the JF cranial nerves were recorded in 34 cadaveric skulls. The volumes of the JF, intraforaminal EDNAC, and internal jugular vein (IJV) were quantified.

RESULTS

Based on constant osseous landmarks, the JF was subdivided into preforaminal, intraforaminal, and subforaminal segments. The ML-derived fascial sheath along the anteromedial wall of the IJV demarcated the "venous portion" and the "EDNAC portion" of the bipartite JF. The EDNAC did not surround the intraforaminal IJV and comprised an ML-derived dural fibrous network and an adipose matrix. A fibrovenous curtain subdivided the intraforaminal EDNAC into a small anterior column containing cranial nerve (CN) IX and the anterior condylar venous plexus and a large posterior adipose column containing CNs X and XI. In the intraforaminal segment, the IJV occupied a slightly larger space in the foramen (57%; p < 0.01), whereas in the subforaminal segment it occupied a space of similar size to that of the EDNAC.

CONCLUSIONS

Excluding the IJV, the neurovascular structures in the JF traverse the dural fibrous network that is dominant in the foraminal EDNAC. The results of this study will contribute to anatomical knowledge of the obscure yet crucially important JF region, increase understanding of foraminal tumor growth and spread patterns, and facilitate the planning and execution of surgical interventions.

Clinical Anatomy of the Extradural Neural Axis Compartment: A Literature Review

OBJECTIVE

The extradural neural axis compartment (EDNAC) is an adipovenous zone located between the meningeal and endosteal layers of the dura and has been minimally investigated. It runs along the neuraxis from the orbits down to the coccyx and contains fat, valveless veins, arteries, and nerves. In the present review, we have outlined the current knowledge regarding the structural and functional significance of the EDNAC.

METHODS

We performed a narrative review of the reported EDNAC data.

RESULTS

The EDNAC can be organized into 4 regional enlargements along its length: the orbital, lateral sellar, clival, and spinal segments, with a lateral sellar orbital junction linking the orbital and lateral sellar segments. The orbital EDNAC facilitates the movement of the eyeball and elsewhere allows limited motility for the meningeal dura. The major nerves and vessels are cushioned and supported by the EDNAC. Increased intra-abdominal pressure will also be conveyed along the spinal EDNAC, causing increased venous pressure in the spine and cranium. From a pathological perspective, the EDNAC functions as a low-resistance, extradural passageway that might facilitate tumor encroachment and expansion.

CONCLUSIONS

Clinicians should be aware of the extent and significance of the EDNAC, which could affect skull base and spine surgery, and have an understanding of the tumor spread pathways and growth patterns. Comparatively little research has focused on the EDNAC since its initial description. Therefore, future investigations are required to provide more information on this underappreciated component of neuraxial anatomy.