The role of needle tip position on the accuracy of diagnostic selective nerve root blocks in spinal deformity

Diagnostic value of curved planar reformation of MRI for lumbosacral nerve roots in the localization of nerve roots for adult lumbar degenerative scoliosis

PURPOSE

To compare the diagnostic value of curved planar reformation of MRI (MRI-CPR) and 2D MRI in determining the responsible nerve in patients with adult lumbar degenerative scoliosis (ALDS).

METHOD

A total of 45 patients diagnosed with ALDS were included in the study. All patients underwent MRI-CPR and 2D MRI and subsequently received surgery. These two diagnostic methods were compared with the results of surgical exploration to assess nerve root compression.

RESULTS

The sensitivity and accuracy of MRI-CPR are higher than 2D MRI (93.8% vs 80.0%; 92.8% vs 77.7%, respectively). And the specificity of MRI-CPR is higher than 2D MRI (87.5% vs 68.8%). Besides, the PPV and NPV of MRI-CPR are higher than 2D MRI (96.8% vs 91.2%; 7.8.% vs 45.8%). The area (AUC) under the receiver operating characteristic curve (ROC) for MRI-CPR and 2D MRI was 0.74 and 0.91, respectively. The judgement was made by two independent radiologists, while the consistency tests for 2D MRI and MRI-CPR with Kappa values were 90.6% and 82.2%, respectively.

CONCLUSIONS

The clinical diagnostic value of MRI-CPR was better than 2D MRI in the determination of the responsible nerve root. Moreover, MRI-CPR sequence images can clearly show the route of lumbosacral nerve roots and their relationship with adjacent tissues. Therefore, MRI-CPR can be an important complement to conventional 2D MRI in the diagnosis of responsible nerve roots in patients with ALDS.

Usefulness of the additional contrast agents to identify offending nerve root in selective nerve root block

It is hypothesized that if it is confirmed that the pain caused by the injection needle coincides with the lower leg radiating pain(LLRP) that the patient mainly complains of, then the contrast agents may be used less. This study aims to understand if the identification of lancinating identical pain in the procedure could replace the use of contrast agents that causes additional pain provocation using control arm of randomized clinical trial.This retrospective study included 165 patients who met exclusion criteria from among patients who underwent Selective nerve root block for the treatment of LLRP. With the identical and lancinating pain confirmed in the same site of the patient, consistent with that of the original symptom, the subjects were divided into 2 groups: 1 without contrast injection (Non-Dye [ND] group; 57 patients) and the other with contrast injection (Dye [D] group; 108 patients). The degree of LLRP in the 2 groups was evaluated using visual analog scale (VAS) before injection, 2, 6, and 12 weeks after injection. Functional outcomes were measured using Owestry Disability Index and Rolland-Morris Disability Questionnair, whereas quality of life was measured using Physical component score and Mental component score of Short Form 36 (SF-36) before injection and 3 months after injection.There was no statistically significant difference in the LLRP severity in both groups at all times and no statistical difference in the degree of VAS improvement relative to the before-injection VAS value between the 2 groups at 2 and 6 weeks after injection (all P > .05). At 12 weeks after injection, there was a statistically significant difference, but they were below Minimum Clinical Important Difference, bearing little clinical implications. There was no statistically significant difference between the 2 groups in Owestry Disability Index, Rolland-Morris Disability Questionnair, SF-36 Physical component score, and SF-36 Mental component score at every interval (all P > .05).Instead of contrast agent injections that have been used for accurate nerve root identification during Selective Nerve Root Block, the method of merely checking if the needle-induced pain under fluoroscopic imaging is consistent with the LLRP that the patient predominantly experiences shows the same effect in the patient's pain control and functional outcome.

Does the Position of the Polyaxial Screw Head in Patients With L5-S1 Stabilization Lead to an Increased Difficulty in L5 Transforaminal Nerve Injection? A Three-Dimensional Computerized Tomography Study

Background

Challenges may be encountered if transforaminal nerve injection (TFNI) is required in patients who have undergone posterior transpedicular stabilization (PTS) surgery to the L5-S1 level. In this study, we investigated the contributory factors that lead to these challenges.

Methods

We selected 125 patients who underwent PTS surgery involving the L5-S1 segment, between 18 to 70 years of age to be included in the study. The demographic data of the patients, body mass indexes (BMI), postoperative spondylolisthesis grades, heights of the iliac crest, and the positions of the polyaxial screw head were assessed. The shortest trajectory of L5-TFNI, the distance of the needle entry point (NEP) to the midline, and optimum viewing angles (VA) were measured on the three-dimensional computed tomography (CT) sections.

Results

Pre-PTS surgery, in males compared to females, NEP was noted to be more medial (p=0.007), the needle trajectory was shorter (p=0.001), and the optimal VA was narrower (p=0.001). Increasing BMI and increasing height of the iliac crest caused the TFNI trajectory to become longer. Post-PTS surgery, angulation of polyaxial screw heads of more than 15 degrees laterally in both genders significantly caused a decrease in VA (p=0.001).

Conclusions

Using the reconstruction technique in 3D CT, we demonstrated that pedicle screw heads angled laterally, a higher iliac crest height, and an increased BMI make L5-TFNI difficult to be performed. Locking the stabilization system while targeting the most neutral position for polyaxial screw heads during surgery may facilitate the L5-TFNI.

Effect of Needle Tip Position on Contrast Media Dispersion Pattern in Transforaminal Epidural Injection Using Kambin's Triangle Approach

Purpose

Dispersion of contrast media into the anterior epidural space is correlated with better outcomes after transforaminal epidural injection (TFEI). Needle tip position is an important factor affecting the pattern of contrast media dispersion. It is difficult to advance the needle medially to the interpedicle line with a conventional approach, especially in a severe spinal stenosis. But, with Kambin’s triangle approach, the needle can be advanced more medially even in the severe stenosis. We aimed to compare contrast media dispersion patterns according to the needle tip position in TFEI with Kambin’s triangle approach.

Patients and Methods

This single-center retrospective study analyzed fluoroscopic data of patients who underwent TFEI from March 2019 to July 2019. Data on the history of lumbar spinal fusion surgery and MRI findings were collected. The needle tip position was evaluated in three positions on fluoroscopic images (final anteroposterior [AP] view): extraforaminal (EF), lateral foramen (LF), and medial foramen (MF). Contrast media dispersion into the epidural space (epidural pattern) in the AP view was evaluated as a dependent variable. The relationship between the contrast media dispersion pattern and needle tip position was analyzed, and other factors affecting the contrast media dispersion pattern were identified.

Results

Ninety-eight TFEI cases were analyzed (51 LF, 35 MF, and 12 EF). An epidural pattern of dispersion was observed more frequently in the LF and MF groups than in the EF group. The LF and MF groups showed no significant difference in epidural pattern frequency. On logistic regression analysis, needle tip position emerged as a major factor influencing epidural pattern, while other factors including spine conditions had no significant effect.

Conclusion

Positioning the needle tip medial to the pedicle helps in the spread of the contrast media into the epidural space during TFEI with Kambin’s approach. Factors other than the needle tip position did not significantly affect the contrast media dispersion pattern.

Accurate location and minimally invasive treatment of lumbar lateral recess stenosis with combined SNRB and PTED

OBJECTIVE

To establish a management strategy for multi-segment lumbar lateral recess stenosis.

METHODS

A retrospective study was performed in patients in whom suspected responsible nerve roots underwent sequential selective nerve root block (SNRB). Based on pain remission rate after blocking, the contribution of nerve root compression to symptoms was classified as absolutely (≥70%) or relatively (30-70%) responsible or non-responsible (<30%). Conservative treatment was continued if visual analogue scale (VAS) at 3 days after blocking a single nerve root or VAS at 3 days after blocking multiple nerve roots was ≥50%; otherwise, percutaneous transforaminal endoscopic discectomy (PTED) was performed. Pain and functional scores were evaluated on day 3, 6 months and 1 year after SNRB or PTED.

RESULTS

Fifty-seven of 80 patients had a single absolutely responsible root, 20 had 2 responsible roots, and 3 had 3 responsible roots. Among them, 41, 10, and 1 patient underwent PTED, respectively. Both the PTED and conservative groups improved significantly in VAS remission rate and functional scores compared with admission. Moreover, the PTED group had a better VAS remission rate compared with the conservative group.

CONCLUSION

A combination of SNRB with PTED was effective for diagnosing and treating multi-segment lumbar lateral recess stenosis.

CT-guided transforaminal epidural steroid injections: do needle position and degree of foraminal stenosis affect the pattern of epidural flow?

OBJECTIVE

To determine the effect of needle position and foraminal stenosis on contrast flow directionality during CT-guided transforaminal epidural steroid injections (TFESI).

MATERIALS AND METHODS

One hundred five consecutive CT-guided injections were performed in 68 patients (mean age, 65.5 years) from January 1 to December 31 2017, all with preceding MRI. Two readers independently reviewed CT images to assess needle position and to determine direction of contrast flow, which was defined as central or peripheral. The MRIs were independently reviewed by the readers to determine the degree of foraminal stenosis. Inter-reader agreement for both was evaluated with the kappa statistic. Analyses were performed to determine effect of needle position, degree of foraminal stenosis, and volume of contrast injected with directionality of contrast flow, and association between contrast flow directionality with immediate post-procedural pain scores.

RESULTS

Central direction of contrast flow was demonstrated in 41/78 (52.6%) of cases with posterolateral needle position, and 20/27 (74.1%) with central or anteromedial needle position (p = 0.07). There was no difference in direction of contrast flow with high-grade versus absence of high-grade neuroforaminal narrowing, or with volume of contrast injected. There was no difference in immediate post-procedure pain scores regardless of contrast flow directionality.

CONCLUSIONS

Needle position is not significantly associated with contrast flow directionality during CT-guided TFESI, although there was a trend towards relatively decreased central flow with posterolateral positioning. Degree of foraminal stenosis and volume of injected contrast did not affect contrast flow directionality. There was no difference in immediate post-procedural pain scores with either direction of contrast flow.

The value of lumbar dorsal root ganglion blocks in predicting the response to decompressive surgery in patients with diagnostic doubt

BACKGROUND CONTEXT

Pain as a consequence of nerve root compression may not be easy to diagnose. Degenerative changes causing nerve root compression on magnetic resonance imaging (MRI) are common but not necessarily symptomatic while the distribution of pain attributable to a particular nerve root is variable. Selective dorsal root ganglion blocks (DRGBs) have been used in these situations to aid the diagnostic process, although their use remains controversial.

PURPOSE

We sought to investigate the positive predictive value of DRGBs in predicting response to decompressive surgery on a particular nerve root in a patient cohort with diagnostic uncertainty after clinical examination and MRI.

STUDY DESIGN/SETTING

This was a retrospective review of prospectively collected data on 100 consecutive patients.

METHODS

One hundred consecutive patients who underwent diagnostic DRGB under the senior author were identified retrospectively. Clinical records were reviewed for the reason for diagnostic uncertainty, level assessed, whether the DRGB reproduced pain typical for the patient's symptoms, whether there was anatomically appropriate sensory and motor disturbance, whether good pain relief was achieved, and whether they had good response to surgery.

RESULTS

Of 100 patients recruited, four were removed from analysis owing to inadequate surgical decompression proven on postoperative MRI. Of the remaining 96 patients, 74 achieved immediate relief in their symptoms after DRGB. Fifty-one patients underwent surgical decompression after a successful root block; 41 patients achieved a good result from this surgery, and 10 did not. Nine patients who had no relief in their symptoms from DRGB still underwent surgery to decompress the same nerve root; six patients had relief of their symptoms from surgery, two did not respond, and one was lost to follow-up. The most common reason for diagnostic uncertainty was multilevel disease (74%) followed by patients with atypical pain (23%). The most common level assessed was the L5 nerve root. The positive predictive value was found to be 80.4%, the negative predictive value was 22.2%, with a sensitivity of 85.4% and a specificity of 16.7%.

CONCLUSIONS

In patients with diagnostic doubt, a positive DRGB is a good predictor of a positive outcome after surgery to decompress that nerve root. However, the negative predictive value is poor. This result could almost certainly be improved if there was a better definition of what constitutes a positive, and more importantly a negative, DRGB result. In the meantime, DRGBs are a useful adjunct in predicting the outcome of decompressive surgery in people with pain as a consequence of potential lumbosacral nerve root compression.