Ultrasound and electrical nerve stimulation-guided S1 nerve root block

Visualization of sacral nerve roots and sacral plexus on gynecological transvaginal ultrasound: feasibility study

OBJECTIVE

To investigate the feasibility of identifying and measuring the normal sacral plexus (SP) on gynecological transvaginal ultrasound (TVS) examination.

METHODS

This was a prospective observational study conducted at a single tertiary gynecological referral center, including consecutive women undergoing TVS for various indications between November 2021 and January 2022. A standardized assessment of the pelvic organs was performed and the presence of any congenital or acquired uterine pathology or ovarian abnormality was recorded. Visualization of the right and left SP was attempted in all cases. The success rate and the time needed to identify the SP were recorded and measurements of the SP were made.

RESULTS

A total of 326 patients were included in the study. In all women, the SP was identified successfully on at least one side. SP were visualized bilaterally in 317 (97.2% (95% CI, 94.4-98.5%)) women. Only the right SP was seen in 3/326 (0.9% (95% CI, 0.2-2.7%)) and only the left in 6/326 (1.8% (95% CI, 0.6-4.0%)) (P = 0.5048). There was no significant difference in the median time required to visualize the right vs left SP (9.0 (interquartile range (IQR), 8.0-10.0) s  vs 9.0 (IQR, 8.0-10.0) s; P = 0.0770). The median transverse diameter of the right SP was 15.0 (IQR, 14.2-15.6) mm and that of the left SP was 14.9 (IQR, 14.4-15.6) mm.

CONCLUSIONS

We describe a novel method which allows for the consistent and rapid identification of the SP on TVS. Integrating assessment of the SP into routine pelvic TVS may be helpful particularly for women suffering from deep endometriosis. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Measurement of S1 foramen depth for ultrasound-guided S1 transforaminal epidural injection

Background

Ultrasound-guided first sacral transforaminal epidural steroid injection (S1 TFESI) is a useful and easily applicable alternative to fluoroscopy or computed tomography (CT) in lumbosacral radiculopathy. When a needle approach is used, poor visualization of the needle tip reduces the accuracy of the procedure, increasing its difficulty. This study aimed to improve ultrasound-guided S1 TFESI by evaluating radiological S1 posterior foramen data obtained using three-dimensional CT (3D-CT).

Methods

Axial 3D-CT images of the pelvis were retrospectively analyzed. The radiological measurements obtained from the images included 1st posterior sacral foramen depth (S1D, mm), 1st posterior sacral foramen width (S1W, mm), the angle of the 1st posterior sacral foramen (S1A, °), and 1st posterior sacral foramen distance (S1ds, mm). The relationship between the demographic factors and measured values were then analyzed.

Results

A total of 632 patients (287 male and 345 female) were examined. The mean S1D values for males and females were 11.9 ± 1.9 mm and 10.6 ± 1.8 mm, respectively (P < 0.001); the mean S1A 28.2 ± 4.8° and 30.1 ± 4.9°, respectively (P < 0.001); and the mean S1ds, 24.1 ± 2.9 mm and 22.9 ± 2.6 mm, respectively (P < 0.001); however, the mean S1W values were not significantly different. Height was the only significant predictor of S1D (β = 0.318, P = 0.004).

Conclusions

Ultrasound-guided S1 TFESI performance and safety may be improved with adjustment of needle insertion depth congruent with the patient's height.

Role of transforaminal epidural injections or selective nerve root blocks in the management of lumbar radicular syndrome - A narrative, evidence-based review

OBJECTIVE

Lumbar radicular Syndrome (LRS) is a common spinal pathology and is attributed to complex interplay of mechanical, inflammatory and immunological processes. Epidural injection of steroids has a significant therapeutic role in mitigating the inflammatory component of LRS. Trans-foraminal approach under image guidance enables a targeted drug delivery. The current narrative review discusses the various aspects related to lumbar trans-foraminal epidural injection of steroid (LTFIS).

METHODS

An elaborate search on PubMed, Google and Medline databases was made using keywords "lumbar selective nerve root block", "lumbar trans-foraminal epidural steroid injection", "selective nerve root block in lumbar disc prolapse", "trans-foraminal epidural steroid injection in lumbar prolapse", "selective nerve root block in lumbar radiculopathy", and "trans-foraminal epidural steroid injection in lumbar radiculopathy" The articles were selected based on specific inclusion criteria.

RESULTS

Our search identified 539 articles. All articles discussing alternate procedures, LTFIS in other pathologies, diagnostic roles of LTFIS, not pertaining to concerned questions, in non-English language and duplicate articles were excluded. Review articles, randomised controlled trials or level 1 studies were given preference. Overall, 108 articles were included. Being a focussed narrative review, further screening [Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) or Methodological Index for non-randomized studies (MINORS) criteria] was not performed to select articles. Based on the evidence, LTFIS is an effective and useful treatment modality. It is offered to patients with lumbar disc herniation (LDH) presenting with persistent, unilateral, radiculopathy after a course of conservative measures for around 6 weeks' duration. It has been reported to yield better results than caudal or inter-laminar epidural injections. The anti-inflammatory and nociceptive signal stabilization actions of steroids, as well as mechanical effects of washout of inflammatory mediators and neural lysis contribute to its efficacy. The three different approaches include sub-pedicular, retro-neural and retro-discal. The procedure is performed under image guidance using a water-soluble contrast under fluoroscopy. The four described radiculogram patterns include "arm", "arrow", "linear" and "splash". Computerised tomography, ultrasonography and magnetic resonance imaging are other modalities, which may be helpful in performing LTFIS. The use of particulate versus non-particulate steroids is controversial.

CONCLUSION

The overall success rate of SNRB is reported to be 76-88%. The majority of benefits are observed during immediate and early post-injection period. Clinical factors including duration and severity of symptoms, and radiological factors like presence of osteophytes, location, size and type of disc prolapse influence outcomes. The radiculogram "splash" pattern is associated with poor outcomes.

A Video of Ultrasound-Guided S1 Transforaminal Epidural Injection Using Color Doppler: Technical Reports

Lumbosacral radicular pain with or without radiculopathy is a fairly common clinical condition. In such cases, lumbosacral transforaminal epidural injection (TFEI) is one of the most commonly performed interventions. Recent studies have explored the effectiveness of ultrasound (US)-guided lumbosacral TFEI. Most of these studies have focused on lumbar TFEI via an in-plane approach. S1 TFEI can also be easily performed, since the S1 foramen is more superficial than the lumbar foramen. However, most studies regarding US-guided sacral TFEI use an out-of-plane technique. Therefore, in this report we present a video of US-guided S1 TFEI via an in-plane approach.

Ultrasound-Guided S1 Transforaminal Epidural Injection Using the In-Plane Approach and Color Doppler Imaging

Recently, several studies have investigated the effectiveness of the ultrasound-guided lumbosacral transforaminal epidural injection. However, the ultrasound-guided S1 transforaminal epidural injection using an out-of-plane approach, which was previously reported, may cause an intestinal injury or intravascular injection because the needle tip tends to be invisible in the out-of-plane approach. In this study, therefore, we report a new method of ultrasound-guided S1 transforaminal epidural injection using the in-plane approach and color Doppler. In addition, we also report the usefulness of color Doppler imaging for finding the S1 foramen and confirming the accuracy of the injection.

Relationship between first dorsal sacral foramen and lumbar facet joint connecting line in South Korea populations: Retrospective study

The first sacral nerve root block (S1 nerve root block) is a practical procedure for patients with radiating lower back pain. In general, S1 nerve root block is performed under x-ray fluoroscopy. It is necessary to adjust the position of the patient and angle of fluoroscopy to properly visualize the first dorsal sacral foramen (dorsal S1 foramen). The purpose of this study was to analyze the location of dorsal S1 foramen and lumbar facet joint in S1 nerve root block.A total of 388 patients undergoing x-ray fluoroscopy-guided S1 nerve root block in the prone position were examined. X-ray fluoroscopy was fixed at the corresponding location of facet joint of L4-5 and L5-S1. The relationship of the connecting line vertical to L5-S1 facet joint and upper margin sacrum was evaluated. The surface anatomical relationships between dorsal S1 foramen and lumbar facet joint were assessed.Based on the localization of dorsal S1 foramen, the line drawn from point to upper margin sacrum passed through the dorsal S1 foramen in all cases. The horizontal distance from the spinous process to the dorsal S1 foramen was 25.9 ± 3.0 mm for men and 26.2 ± 1.4 mm for women. The horizontal distance from the between posterior superioriliac spine to the dorsal S1 foramen was 26.2 ± 2.7 mm for men and 26.8 ± 1.7 mm for women. The vertical distance from the upper margin of sacrum to dorsal S1 foramen to the dorsal S1 foramen was 45.6 ± 6.5 mm for men and 43.8 ± 6.0 mm for women.The connecting line vertical to L5-S1 facet joint and upper margin sacrum is located on the same line from the dorsal S1 foramen. For difficult cases of locating dorsal S1 foramen, the lumbar facet joint can assist in predicting the vertical location of the dorsal S1 foramen.