Diagnostic Value and Surgical Implications of the 3D DW-SSFP MRI On the Management of Patients with Brachial Plexus Injuries

The Application of Contrast-Enhanced 3D-STIR-VISTA MR Imaging of the Brachial Plexus

Objective:

Methods:

Results:

Conclusion:

Diagnostic Ability of Ultrasonography in Brachial Plexus Root Injury at Different Stages Post-trauma

Brachial plexus (BP) root injury often results in disability of the upper extremities. Improvements in high-frequency ultrasonography have enabled the visualization of BP nerve roots. This study was aimed at quantifying the diagnostic accuracy of ultrasonography in BP root injury at different stages post-trauma. A consecutive series of 170 patients with BP root injury between 2015 and 2019 were studied retrospectively and divided into three groups on the basis of time between injury and ultrasound examination (≤1 mo, 1-3 mo, >3 mo). Diagnosis of complete BP root injury under ultrasound was determined using a pre-defined criterion, including pseudomeningocele, retraction and rupture. Diagnostic accuracy was calculated based on surgical findings and intra-operative electrophysiological tests. Rates of detection of the cervical (C5-C8) and thoracic (T1) nerve roots under ultrasound were 99.4%, 99.4%, 99.4%, 95.9% and 79.4%, respectively. The sensitivity for complete BP root injury was 0.74, and the specificity was 0.91. No significant differences in sensitivity or specificity were observed across time stages. Ultrasound exhibited substantial consistency with surgical findings (κ = 0.70) for complete BP root injury at any stage post-injury. Ultrasound can be an optional method of diagnosis of complete BP root injury at an early stage post-injury.

Magnetic resonance imaging of the brachial plexus. Part 1: Anatomical considerations, magnetic resonance techniques, and non-traumatic lesions

For magnetic resonance imaging (MRI) of non-traumatic brachial plexus (BP) lesions, sequences with contrast injection should be considered in the differentiation between tumors, infection, postoperative conditions, and post-radiation changes. The most common non-traumatic inflammatory BP neuropathy is radiation neuropathy. T2-weighted images may help to distinguish neoplastic infiltration showing a high signal from radiation-induced neuropathy with fibrosis presenting a low signal.

MRI findings in inflammatory BP neuropathy are usually absent or discrete. Diffuse edema of the BP localized mainly in the supraclavicular part of BP, with side-to-side differences, and shoulder muscle denervation may be found on MRI.

BP infection is caused by direct infiltration from septic arthritis of the shoulder joint, spondylodiscitis, or lung empyema.

MRI may help to narrow down the list of differential diagnoses of tumors. The most common tumor of BP is metastasis. The most common primary tumor of BP is neurofibroma, which is visible as fusiform thickening of a nerve. In its solitary state, it may be challenging to differentiate from a schwannoma.

The most common MRI finding is a neurogenic variant of thoracic outlet syndrome with an asymmetry of signal and thickness of the BP with edema. In abduction, a loss of fat directly related to the BP may be seen.

Diffusion tensor imaging is a promising novel MRI sequences; however, the small diameter of the nerves contributing to the BP and susceptibility to artifacts may be challenging in obtaining sufficiently high-quality images.

•

MRI allows narrowing the list of differential diagnoses of brachial plexus lesions.

•

MRI helps to distinguish neoplastic infiltration from radiation neuropathy in T2-weighted images.

•

Differentiation between tumors, infection, postoperative conditions and post-radiation changes is possible with contrast.

•

MRI helps to determine the extent of the infection.

•

Diffusion tensor MRI is a promising method for brachial plexus assessment.

Magnetic resonance imaging of the brachial plexus. Part 2: Traumatic injuries

The most common indications for magnetic resonance imaging (MRI) of the brachial plexus (BP) are traumatic injuries. The role of MRI of the BP has increased because of recent trends favoring earlier surgery. Determining preganglionic vs. postganglionic injury is essential, as different treatment strategies are required. Thus, MRI of the BP should be supplemented with cervical spine MRI to assess the intradural part of the spinal nerves, including highly T2-weighted techniques. Acute preganglionic injuries usually manifest as various combinations of post-traumatic pseudomeningocele, the absence of roots, deformity of nerve root sleeves, displacement of the spinal cord, hemorrhage in the spinal canal, presence of scars in the spinal canal, denervation of the back muscles, and syrinx. Spinal nerve root absence is more specific than pseudomeningocele on MRI. Acute postganglionic injuries can present as lesions in continuity or tears. The following signs indicate injury to the BP: side-to-side difference, swelling, partial, or total BP rupture. Injury patterns and localization are associated with the mechanism of trauma, which implies a significant role for MRI in the work-up of patients.

The identification and description of traumatic lesions involving the brachial plexus need to be systematic and detailed. Using an appropriate MRI protocol, obtaining details about the injury, applying a systematic anatomical approach, and correlating imaging findings to relevant clinical data to make a correct diagnosis. Information about the presence or suspicion of root avulsion should always be provided.

•

Trauma is the most common indication for MRI of the brachial plexus.

•

MRI of the brachial plexus should include cervical spine MRI.

•

Spinal nerve root absence is seen in preganglionic injuries.

•

Determining preganglionic vs. postganglionic injury is essential for treatment planning.

•

Appropriate MRI rapport is crucial in communication with the clinician.

Success with dorsal root entry zone lesioning after a failed trial of spinal cord stimulation in a patient with pain due to brachial plexus avulsion

Pain caused by brachial plexopathy (BP) represents a challenging clinical problem with few effective therapeutic options. Here, we present a patient with severe, painful BP after a high-impact motor vehicle accident who failed conservative treatments. A trial of cervical spinal cord stimulation was completed using multiple waveforms (tonic, BurstDR, and 10 kHz) over 14 days with only 30% to 40% pain reduction. Subsequently, he underwent dorsal root entry zone lesioning with a significant decrease in his pain 1 year later. Surgical exploration revealed extensive damage and avulsion of his cervical roots that was not observed on a previous brachial plexus magnetic resonance imaging. We discuss the etiology and diagnosis of traumatic BP, possible reasons for the failed spinal cord stimulation trial, and implications for management.

Diagnostic Accuracy of the Magnetic Resonance Imaging in Adult Post-Ganglionic Brachial Plexus Traumatic Injuries: A Systematic Review and Meta-Analysis

Background: Traumatic brachial plexus injuries are rare but serious consequences of major traumas. Pre-ganglionic lesions are considered irreparable, while post-ganglionic injuries can be potentially treated if an early diagnosis is available. Pre-surgical diagnosis is important to distinguish low-grade from high-grade lesions and to identify their location. The aim of the review is to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) in the identification of adult post-ganglionic lesions due to traumatic brachial plexus injuries, compared to intraoperative findings. Methods: Research on the main scientific electronic databases was conducted. Studies of adults with traumatic post-ganglionic brachial plexus injuries were included. The index test was preoperative MRI and the reference standard was surgical exploration. Pooled sensitivity and specificity were calculated. Results: Four studies were included for the systematic review, of which three articles met the inclusion criteria for the meta-analysis. Pooled sensitivity and pooled specificity values resulted high. The sensitivity value is associated with a high heterogeneity index of the selected literature. Conclusion: MRI can be considered, despite the limits, the gold standard exam in morphological evaluation of brachial plexus injuries, particularly in the diagnosis of post-ganglionic traumatic injuries.

Diagnostic Function of 3-Tesla Magnetic Resonance Imaging for the Assessment of Brachial Plexus Injury

Background:

This study aimed to evaluate the diagnostic function of 3-Tesla (T) magnetic resonance imaging (MRI) during the assessment of brachial plexus injury (BPI), in comparison with intraoperative findings.

Methods:

A retrospective study was performed on 60 patients (47 men and 13 women), who had clinical manifestations of BPI, underwent 3T MRI of the brachial plexus, and were surgically treated at the Viet Duc and Vinmec Times City hospitals, in Hanoi, Vietnam, from March 2016 to December 2019. Preganglionic and postganglionic lesion features were identified on MRI. The diagnostic function of MRI features for the determination of BPI was evaluated and correlated with intraoperative findings.

Results:

The root avulsion and pseudomeningocele preganglionic injuries were observed in 57% and 43% of MRIs, respectively, and were commonly observed at the C7 and C8 roots. Nerve disruption and never edema were observed in 47.56% and 33.53% of MRIs, respectively, and were commonly observed at the C5 and C6 roots. The sensitivity, specificity, accuracy, positive prognostic value, and negative prognostic value of 3T MRI were 64.12%, 92.90%, 80.33%, 87.50%, and 76.96%, respectively, for the diagnosis of total avulsion, and 68.52%, 83.33%, 80.67%, 47.44%, and 92.34%, respectively, for the diagnosis of nerve disruption.

Conclusion:

MRI offers valuable details regarding the location, morphology, and severity of both preganglionic and postganglionic injuries during the preoperative diagnosis of BPI. However, this modality played a moderate diagnostic role. Therefore, 3T MRI should be used as a supplemental evaluation, coupled with clinical tests and electromyography, to determine the most appropriate treatment strategies for BPI patients.

Performance of an Interactive Upper Extremity Peripheral Nerve Training Module Among Medical Students, Radiology Residents, and Fellows: A Multi-institutional Study

BACKGROUND AND PURPOSE

Chronic pain is a common problem and imaging is becoming increasingly utilized in the characterization of peripheral neuropathy, although this topic is not emphasized during medical training. We hypothesized that an electronic module and nerve atlas would be effective in improving comprehension among trainees.

MATERIALS AND METHODS

In this IRB-approved study, a training module was created that included a side-by-side comparison of normal upper extremity nerves on magnetic resonance imaging and ultrasound (US), with embedded questions and cases, followed by a brief hands-on US scanning session. Thirty volunteers with variable training were enrolled in 1 institution, while 14 volunteers were enrolled in another. Pre- and post-test scores were collected and compared.

RESULTS

There was a response rate of 100% at both institutions. At the first institution, subjects were divided into 2 groups: group 1 (16 medical students) and group 2 (14 residents/fellows). There was a baseline deficit of knowledge among both groups, with a mean pretest score of 37.5% and 47.5% for group 1 and group 2, respectively (P = 0.017). After module completion, both groups improved with a mean post-test score of 67.2% for group 1 and 76.1% for group 2. At the second institution, there was similar improvement even if the scanning session was not done.

CONCLUSIONS

Use of an electronic module helps trainees to become more familiar with peripheral nerve imaging, regardless of level of training. Use of the module, even in the absence of hands-on US scanning, results in an improved understanding of this topic.

Clinical Value and Diagnostic Accuracy of 3.0T Multi-Parameter Magnetic Resonance Imaging in Traumatic Brachial Plexus Injury

Background

The aim of this study was to evaluate the clinical value and diagnostic accuracy of 3.0T multi-parameter magnetic resonance imaging (MRI) in traumatic brachial plexus injury.

Material/Methods

Twenty-five healthy volunteers and 28 patients with clinically confirmed traumatic brachial plexus injury were enrolled in this study. Bilateral brachial plexus imaging was performed using conventional sequences (T1WI, T2WI), short time inversion recovery (STIR), balanced fast field echo (balance-FFE), and diffusion weighted imaging with background suppression (DWIBS). The MRI diagnosis was compared with intraoperative electromyography and surgery.

Results

Brachial plexus injuries were classified based on the anatomic locations. There were 16 patients with pre-ganglionic injury and 12 patients with post-ganglionic injury. The pre-ganglionic injury included ruptured nerve roots, stiff nerve roots, traumatic meningeal cysts, black line sign, spinal cord edema, and thickened nerve root sleeve. The post-ganglionic injury included thickened nerve roots, disappearance of normal nerve root structure or disrupted continuity of the nerve, stiff nerve roots, pseudo-neuroma, and abnormalities in the adjacent soft tissues. Comparing the results from MRI and surgery, the sensitivity, specificity, and accuracy of MRI examination were 93.55%, 71.43%, and 89.47% respectively for preganglionic injury, and 91.30%, 60.00%, and 85.71% respectively for postganglionic injury.

Conclusions

The combination of STIR, balance-FFE, and DWIBS sequences can display brachial plexus pre-ganglionic and post-ganglionic injury clearly, effectively, and accurately.

The diagnostic accuracy of 1.5T magnetic resonance imaging for detecting root avulsions in traumatic adult brachial plexus injuries

Identification of root avulsions is of critical importance in traumatic brachial plexus injuries because it alters the reconstruction and prognosis. Pre-operative magnetic resonance imaging is gaining popularity, but there is limited and conflicting data on its diagnostic accuracy for root avulsion. This cohort study describes consecutive patients requiring brachial plexus exploration following trauma between 2008 and 2016. The index test was magnetic resonance imaging at 1.5 Tesla and the reference test was operative exploration of the supraclavicular plexus. Complete data from 29 males was available. The diagnostic accuracy of magnetic resonance imaging for root avulsion(s) of C5-T1 was 79%. The diagnostic accuracy of a pseudomeningocoele as a surrogate marker of root avulsion(s) of C5-T1 was 68%. We conclude that pseudomeningocoles were not a reliable sign of root avulsion and magnetic resonance imaging has modest diagnostic accuracy for root avulsions in the context of adult traumatic brachial plexus injuries.

LEVEL OF EVIDENCE

III.

MR neurography in traumatic, non-obstetric paediatric brachial plexopathy

OBJECTIVES

Many studies have elaborated on the role of magnetic resonance neurography (MRN) in evaluating traumatic brachial plexopathies. Most of these deal with MR findings in adult traumatic plexopathies or children with obstetric brachial plexus palsy (OBPP). Hence, the authors felt the need for this particular study, which focuses on MRN findings in children with non-obstetric traumatic brachial plexus palsy, to find out the distribution and severity of injuries in these patients.

METHODS

This was a single-institution, prospective study conducted between April 2015 and June 2016. All children presenting to the hospital with features of brachial plexopathy and a history of non-obstetric trauma were included in the study.

RESULTS

At MRN, we looked for signs of injury at three levels: roots, trunks and cords. Signs of injury were found at the level of the roots in 22 patients (88%), at the level of the trunks in 20 patients (80%) and at the level of the cords in 22 patients (88%).

CONCLUSIONS

This study, conducted on children suffering from non-obstetric, traumatic brachial plexopathy returned some interesting conclusions including that when the paediatric plexus is injured, the injury is severe and multi-level, with a very high incidence of root injuries.

KEY POINTS

• Brachial plexus injury in paediatric age group is a devastating injury. • The most common cause of this is trauma sustained during birth. • Other causes include road traffic accidents and blunt injury. • MR neurography has revolutionised the diagnosis of brachial plexopathy.

Role of MR Neurography for the Diagnosis of Peripheral Trigeminal Nerve Injuries in Patients with Prior Molar Tooth Extraction

BACKGROUND AND PURPOSE

Clinical neurosensory testing is an imperfect reference standard to evaluate molar tooth extraction related peripheral trigeminal neuropathy. The purpose was to evaluate the diagnostic accuracy of MR neurography in this domain and correlation with neurosensory testing and surgery.

MATERIALS AND METHODS

In this retrospective study, nerve caliber, T2 signal intensity ratio, and contrast-to-noise ratios were recorded by 2 observers using MR neurography for bilateral branches of the peripheral trigeminal nerve, the inferior alveolar and lingual nerves. Patient demographics and correlation of the MR neurography findings with the Sunderland classification of nerve injury and intraoperative findings of surgical patients were obtained.

RESULTS

Among 42 patients, the mean ± SD age for case and control patients were 35.8 ± 10.2 years and 43.2 ± 11.5 years, respectively, with male-to-female ratios of 1:1.4 and 1:5, respectively. Case subjects (peripheral trigeminal neuropathy or injury) had significantly larger differences in nerve thickness, T2 signal intensity ratio, and contrast-to-noise ratios than control patients for the inferior alveolar nerve and lingual nerve (P = .01 and .0001, .012 and .005, and .01 and .01, respectively). Receiver operating characteristic analysis showed a significant association among differences in nerve thickness, T2 signal intensity ratio, and contrast-to-noise ratios and nerve injury (area under the curve, 0.83-0.84 for the inferior alveolar nerve and 0.77-0.78 for the lingual nerve). Interobserver agreement was good for the inferior alveolar nerve (intraclass correlation coefficient, 0.70-0.79) and good to excellent for the lingual nerve (intraclass correlation coefficient, 0.75-0.85). MR neurography correlations with respect to clinical neurosensory testing and surgical classifications were moderate to good. Pearson correlation coefficients of 0.68 and 0.81 and κ of 0.60 and 0.77 were observed for differences in nerve thickness.

CONCLUSIONS

MR neurography can be reliably used for the diagnosis of injuries to the peripheral trigeminal nerve related to molar tooth extractions, with good to excellent correlation of imaging with clinical findings and surgical results.