The location of the intervertebral lumbar disc on the posterior aspect of the spine

Central neuraxial blocks (CNBs), which include spinal, epidural, and combined spinal epidural injections, are indispensable techniques in the anesthesiologist's armamentarium. Indeed, in scenarios such as when dealing with the obstetric population, patients with obesity, or patients having respiratory compromise (e.g., lung disease or scoliosis), CNBs are the mainstay for anesthesia and/or analgesia. Traditionally, CNBs are performed using anatomical landmarks, which are simple, easy to master, and exceptionally successful in most cases. Nevertheless, there are notable limitations with this approach, especially in scenarios where CNBs are considered mandatory and vital. Any limitation of an anatomic landmark-based approach is an opportunity for an ultrasound-guided (USG) technique. This has become particularly true for CNBs, where recent advances in ultrasound technology and research data have addressed many of the shortcomings of the traditional anatomic landmark-based approaches. This article reviews the ultrasound imaging of the lumbosacral spine and its application for CNBs.

This study is a retrospective evaluation of patients with L4-5 highly down-migrated lumbar disc herniation (LDH) operated with interlaminar endoscopic lumbar discectomy (IELD) versus transforaminal endoscopic lumbar discectomy (TELD).

From January 2015 to December 2018, 77 patients with L4-5 highly down-migrated LDH were divided into 2 groups according to different surgical approaches. There were 40 patients who underwent IELD, and 37 patients who underwent TELD. The operation time, hospital stay, Oswestry Disability Index, clinical outcome according with modified MacNab criteria, Visual Analog Scale (VAS) scores, and complications were compared between the IELD and TELD groups.

Seventy-seven patients were included, 40 and 37 patients underwent IELD and TELD, respectively. The IELD and TELD groups both achieved a significant improvement in Oswestry Disability Index, back and leg VAS scores, and clinical outcome postoperation. Mean operating and x-ray times during operation were significantly shorter in the IELD group than in the TELD group (41.8 vs. 50.3, 1.8 vs. 13.7). There were 3 patients who experienced recurrence in the IELD group and 2 in the TELD group. In the TELD group, there were 3 patients who required revision surgery due to incompletely removed disc fragment. All patients in the IELD group were treated successfully. There was no other complication in these cases.

Both IELD and TELD could be a good alternative option for highly down-migrated LDH in L4-L5. IELD may have advantages in operation time and x-ray times during operation compared with TELD.

To prevent risk of iatrogenic instability after surgery for upper lumbar disc herniation, we adapted a microsurgical translaminar approach (keyhole laminotomy), which allows less destructive laminotomy. We compared results of translaminar and interlaminar approaches.

The study enrolled 48 patients who underwent single-level discectomy in the upper lumbar spine (L1-2 or L2-3). Patients were allocated to 2 groups: a translaminar group (n = 20) or an interlaminar group (n = 28). Mean patient age was 57.04 ± 12.77 years, and median follow-up duration was 3.5 years (range, 1.0–7.0 years). Clinical and radiologic data were retrospectively reviewed.

Baseline characteristics, including age, sex, surgical level, and preoperative symptoms, were nonsignificantly different. At 1 year after surgery, improvement in leg pain as determined by visual analog scale was nonsignificantly different. Improvement in visual analog scale for back pain was significantly greater in the translaminar group compared with interlaminar group (mean 4.00 ± 1.56 vs. 2.45 ± 2.01, P < 0.001). Surgical outcome was not different between groups. Mean decrease in disc height at operated level was not significantly different between groups. Mean increase in segmental range of motion at surgical levels was significantly greater in the interlaminar group (−3.38 ± 4.03° vs. 1.10 ± 3.03°, P = 0.010), and mean recovery of total lumbar lordosis was significantly greater in the translaminar group (9.80 ± 5.96° vs. 0.43 ± 8.45°, P = 0.021).

The translaminar approach provides a safe and effective alternative to the classic interlaminar approach for upper lumbar disc herniation.

The extraforaminal ligaments between the L5 and S1 lumbar spinal nerves and the tissues surrounding the intervertebral foramina have been well studied. However, little research has been undertaken to describe the local anatomy of the intraforaminal portion of the L5–S1 spine and detailed anatomical studies of the intraforaminal ligaments (IFLs) of the L5–S1 have not been performed.

The objective of this study was to identify and describe the IFLs in relation to the L5–S1 intervertebral foramen (IVF) and to determine their clinical significance.

A dissection-based study of five embalmed and five fresh-frozen human cadavers was carried out.

Twenty L5–S1 intervertebral foramina from five embalmed cadavers and five fresh cadavers were studied, and the IFLs were identified. The quantity, morphology, origin, insertion, and spatial orientation of the IFLs in the L5–S1 region were observed. The length, width, diameter, and thickness of the ligaments were measured with a vernier caliper. This study has been supported by grants from the National Natural Science Foundation of China (Grant No. 31271286) without potential conflict of interest-associated biases in the text of the paper.

The IFLs could be found from the entrance zone (inside) to the exit zone (outside) of the L5–S1 IVF. These ligaments were found to be of two types: a radiating ligament, which connected the nerve root sleeves that radiated to the transverse processes and wall of the IVF, and a transforaminal ligament, which connected the structures around the IVF. In our study, the radiating ligaments were found more often than the transforaminal ligaments.

The results demonstrate that IFLs are common structures in the IVF and that there are two types of IFLs: the transforaminal ligaments and the radiating ligaments. Transforaminal ligaments may be the potential cause of back pain. The radiating ligaments may contribute to dura laceration and epidural hemorrhage during endoscopic spinal adhesiolysis through the sacral hiatus, and an appreciation of this relationship might help reduce the risk of such complications.

To analyze the surgical strategy, safety and clinical outcome of full-endoscopic discectomy through interlaminar approach in the case of L5/S1 intervertebral disc excision.

From April 2011 to December 2011, 72 cases of intracanalicular non-contained disc herniations at L5/S1 level were treated with full-endoscopic discectomy through interlaminar approach. L5/S1 disc herniation was divided into three types according to position of herniated disc related to S1 nerve root: axilla type, ventral type and shoulder type. Axilla approach was selected for axilla type while shoulder approach was selected for ventral type and shoulder type. After operation, MRI was reexamined to evaluate the resection completeness of prolapsed disc material. Visual analog scales (VAS) of low back pain and sciatica, and Oswestry disability index (ODI) were recorded in certain preoperative and postoperative time points. MacNab scores were evaluated at the 12-month follow-up.

All operations were completed without conversion to other surgical techniques. Average operation time was 45 min (20–80 min). Only one reoccurrence was revised with microendoscopic discectomy. No nerve injury and infection were complicated. Postoperative ODI and VAS of low back pain and sciatica were significantly decreased in each time point (P < 0.05). MacNab scores of 12-month follow-up include 44 excellent, 26 good, 1 fair and 1 poor.

With proper selection between axilla approach and shoulder approach according to the sites of prolapsed or sequestered disc materials, full-endoscopic L5/S1 discectomy through interlaminar approach is a safe, rational and effective minimally invasive spine surgery technique with excellent clinical short-term outcomes.

The far lateral approaches to the lumbar spine require accurate knowledge of regional anatomy. The aim of this study is to evaluate the course of the lumbar nerve roots and their relation to important bony landmarks. Seven adult male cadavers fixed with formaldehyde were used. Morphometric parameters, including the lumbar nerve root diameters, the angle between the nerve roots and the midline, the transverse process length, the inter-transverse process height and width, and the relation between the nerve roots and the transverse processes of the caudal vertebrae were measured. It was observed that the diameter of the nerve roots, and the angle between the nerve roots and the midline, and the distance between the nerve roots and the lateral edge of the superior articular process increased gradually from L1 to L5. The diameter of the nerve root was 4.9 ± 0.5 mm for L1 and 7.5 ± 1.0 mm for L5. The midline nerve root angle was 36.1 ± 1.6° mm for L1 and 40.4 ± 1.4° mm for L5. The distance between the nerve root and the lateral edge of the superior articular process was 6.5 ± 1.0 mm for L1 and 11.4 ± 1.6 mm for L5. The nerve roots crossed the transverse processes of the caudal lumbar vertebrae. The nerve roots of L1 and L2 crossed the transverse processes in their first two quarters, the L3 nerve root crossed the transverse process in its second, third or fourth quarters, and the L4 nerve roots crossed the L5 transverse process in its third and fourth quarter or even external to it. Descending toward the lower lumbar vertebrae, the diameter of the lumbar nerve root increases and the nerve roots exit the intervertebral foramen with a larger angle. The special relation between the nerve roots and the caudal vertebra transverse process should be remembered during far lateral lumbar spine approaches.