Avulsion injury of cervical nerve roots: enhanced intradural nerve roots at MR imaging

A pentavalent approach for the evaluation of traumatic brachial plexopathy on MRI: correlation of macropattern and micropattern

Macropattern analysis of traumatic brachial plexopathy (TBP) by Magnetic Resonance Imaging (MRI) encompasses localization of injured segments and determination of the severity of injury. The micropattern analysis implies the correlation of the MRI features of TBP with Sunderland's grading of the nerve injury, thereby guiding the management protocol. This review article presents a simplified novel pentavalent approach for the radiological anatomy of brachial plexus, MRI acquisition protocol for the evaluation of brachial plexus, cardinal imaging signs of TBP, and their correlation with Sunderland's microanatomical grading.

Diagnostic accuracy of imaging studies for diagnosing root avulsions in post-traumatic upper brachial plexus traction injuries in adults

BACKGROUND

There is no consensus about which type of imaging study, computed tomography myelography (CTM) or magnetic resonance imaging (MRI), provides better information concerning root avulsion in adult brachial plexus injuries.

METHODS

Patients with upper brachial plexus traumatic injuries underwent both CTM and MRI and surgical exploration. The imaging studies were analyzed by two independent radiologists and the data were compared with the intraoperative findings. The statistical analysis was based on dichotomous classification of the nerve roots (normal or altered). The interobserver agreement was assessed using Cohen's Kappa. The accuracy of CTM and MRI in comparison with the intraoperative findings was evaluated using the same methodology.

RESULTS

Fifty-two adult patients were included. CTM tended to yield slightly higher percentages of alterations than MRI The interobserver agreement was better on CTM than on MRI for all nerve roots: C5, 0.9960 (strong) vs. 0.145 (poor); C6, 0.970 (strong) vs. 0.788 (substantial); C7, 0.969 (strong) vs. 0.848 (strong). The accuracy regarding the intraoperative findings was also higher on CTM (moderate, kappa 0.40-0.59) than on MRI (minimal, kappa 0.20-0.39) for all nerve roots. Accordingly, the overall percentage concordance (both normal or both altered) was superior in the CTM evaluation (approx. 70-75% vs. 60-65%). CTM was superior for both sensitivity and specificity at all nerve roots.

CONCLUSION

CTM had greater interobserver agreement and higher diagnostic accuracy than MRI in adult patients with root avulsions due to brachial plexus injury.

Practical applications of CISS MRI in spine imaging

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Conventional spin echo imaging is limited by low spatial resolution and CSF pulsation artifact.

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CISS MRI enables submillimeter spatial resolution and myelographic contrast.

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Inherent flow compensation of the CISS technique reduces CSF pulsation artifact.

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CISS improves the delineation of a wide variety of spinal pathologies.

Routine magnetic resonance imaging evaluation of the spine is often limited by low spatial resolution and artifacts resulting from cerebrospinal fluid pulsation. Balanced steady-state free precession sequences can supplement routine spin echo sequences and provide exquisite anatomic detail and high cerebrospinal fluid-to-soft tissue contrast, adding significant diagnostic value to the evaluation of a wide variety of spine disorders.

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.

Magnetic resonance imaging in brachial plexus injury

Brachial plexus injury represents the most severe nerve injury of the extremities. While obstetric brachial plexus injury has showed a reduction in the number of cases due to the improvements in obstetric care, brachial plexus injury in the adult is an increasingly common clinical problem. The therapeutic measures depend on the pathologic condition and the location of the injury: Preganglionic avulsions are usually not amenable to surgical repair; function of some denervated muscles can be restored with nerve transfers from intercostals or accessory nerves and contralateral C7 transfer. Postganglionic avulsions are repaired with excision of the damaged segment and nerve autograft between nerve ends or followed up conservatively. Magnetic resonance imaging is the modality of choice for depicting the anatomy and pathology of the brachial plexus: It demonstrates the location of the nerve damage (crucial for optimal treatment planning), depicts the nerve continuity (with or without neuroma formation), or may show a completely disrupted/avulsed nerve, thereby aiding in nerve-injury grading for preoperative planning. Computed tomography myelography has the advantage of a higher spatial resolution in demonstration of nerve roots compared with MR myelography; however, it is invasive and shows some difficulties in the depiction of some pseudomeningoceles with little or no communication with the dural sac.

Assessment of the usefulness of X-ray myelography and magnetic resonance myelography, performed with an open low-field device, in diagnosing perinatal preganglionic injuries of the brachial plexus

INTRODUCTION

The goal is to assess the usefulness of diagnostic imaging in diagnosing perinatal preganglionic injuries of the brachial plexus.

MATERIAL AND METHODS

The clinical material included 40 children of both genders, aged 2 to 35 months. The authors analysed the results of diagnostic imaging examinations (myelography in 20 cases and magnetic resonance [MR] myelography in 20 cases), intraoperative view and clinical course.

RESULTS

In 13 out of 40 (32.5%) examined children, no evidence of avulsion of the roots of the spinal nerves was found either by diagnostic imaging or during the surgery. In 3 cases (7.5%) with avulsed roots of the spinal nerves, the diagnostic imaging and intraoperative appearance were in agreement. Total agreement of the diagnostic imaging and intraoperative view was found in 40% of cases. In 9 patients (22.5%) suspected avulsion of roots of the spinal nerves was not confirmed during the surgery. However, the further clinical course of the disease in these cases indicated high probability of avulsion of roots without their pull-out from the intervertebral foramens. In the remaining cases, the findings were as follows: false positive results - 7 (17.5%), false negative results - 1 (2.5%), results underestimating injury - 3 (7.5%), results overestimating injury - 2 (5%).

CONCLUSIONS

It was determined that the usefulness of pre-operative diagnostic imaging is limited. Due to the risk of occurrence of false positive and false negative results, final decisions concerning selection of the surgical technique must be based on the analysis of the intraoperative view and preoperative clinical symptoms.

Brain reorganization in patients with brachial plexus injury: a longitudinal functional MRI study

The aim of this study is to assess plastic changes of the sensorimotor cortex (SMC) in patients with traumatic brachial plexus injury (BPI) using functional magnetic resonance imaging (fMRI). Twenty patients with traumatic BPI underwent fMRI using blood oxygen level-dependent technique with echo-planar imaging before the operation. Sixteen patients underwent their second fMRI at approximately one year after injury. The subjects performed two tasks: a flexion-extension task of the affected elbow and a task of the unaffected elbow. After activation, maps were generated, the number of significantly activated voxels in SMC contralateral to the elbow movement in the affected elbow task study (N_af) and that in the unaffected task study (N_unaf) were counted. An asymmetry index (AI) was calculated, where AI = (N_af − N_unaf)/(N_af + N_unaf). Ten healthy volunteers were also included in this fMRI study. The AI of the first fMRI of the patients with BPI was significantly lower than that of the healthy subjects (P = 0.035). The AI of the second fMRI significantly decreased compared with that of the first fMRI (P = 0.045). Brain reorganization associates with peripheral nervous changes after BPI and after operation for functional reconstruction.

MRI of the brachial plexus: a pictorial review

Magnetic resonance imaging (MRI) of the brachial plexus is the imaging modality of first choice for depicting anatomy and pathology of the brachial plexus. The anatomy of the roots, trunks, divisions and cords is very well depicted due to the inherent contrast differences between the nerves and the surrounding fat. In this pictorial review the technique and the anatomy will be discussed. The following pathology will be addressed: neurogenic tumors of the brachial plexus and sympathetic chain, superior sulcus tumors, other tumors in the vicinity of the brachial plexus, the differentiation between radiation and metastatic plexopathy, trauma, neurogenic thoracic outlet syndrome and immune-mediated neuropathies.

Bezier surface reformation: an original visualization technique of cervical nerve roots on myelographic CT

PURPOSE

The aim of this study was to assess the feasibility of an original reformation method of cervical myelographic computed tomography (CT) using the Bezier surface technique.

MATERIAL AND METHODS

Presurgical myelographic computed tomography (CT) scans using a multidetector row CT scanner were performed in 25 patients with avulsion injury of the cervical nerve roots. Each volumetric data set was reformatted using Bezier surface technique to depict the individual nerve root in a single image. In the reformatted images, visualization of the dorsal and ventral nerve roots between C4 and T1 on the uninjured side (300 nerves) was rated.

RESULTS

Bezier surface reformation (BSR) images depicted the dorsal and the ventral nerve roots between C4 and C8 in 125 (100%) and 125 (100%) of 125 nerves, respectively. The dorsal and the ventral nerve roots of T1 were depicted in 25 (100%) and 22 (88%) in 25 nerves, respectively.

CONCLUSION

The BSR technique of cervical myelographic CT enables simultaneous display of multiple cervical nerve roots in one image. BSR is a feasible technique for the assessment of the cervical nerve roots.

Brachial Plexus Injury: Clinical Manifestations, Conventional Imaging Findings, and the Latest Imaging Techniques

Brachial plexus injury (BPI) is a severe neurologic injury that causes functional impairment of the affected upper limb. Imaging studies play an essential role in differentiating between preganglionic and postganglionic injuries, a distinction that is crucial for optimal treatment planning. Findings at standard myelography, computed tomographic (CT) myelography, and conventional magnetic resonance (MR) imaging help determine the location and severity of injuries. MR imaging sometimes demonstrates signal intensity changes in the spinal cord, and enhancement of nerve roots and paraspinal muscles at MR imaging indicates the presence of root avulsion injuries. New techniques including MR myelography, diffusion-weighted neurography, and Bezier surface reformation can also be useful in the evaluation and management of BPI. MR myelography with state-of-the-art technology yields remarkably high-quality images, although it cannot replace CT myelography entirely. Diffusion-weighted neurography is a cutting-edge technique for visualizing postganglionic nerve roots. Bezier surface reformation allows the depiction of entire intradural nerve roots on a single image. CT myelography appears to be the preferred initial imaging modality, with standard myelography and contrast material-enhanced MR imaging being recommended as additional studies. Work-up will vary depending on the equipment used, the management policy of peripheral nerve surgeons, and, most important, the individual patient.

Concordance and Discrepancy between Electrodiagnosis and Magnetic Resonance Imaging in Cervical Root Avulsion Injuries

To clarify the relationships between electromyography (EMG) and magnetic resonance imaging (MRI), we compared findings in 37 selected patients who presented with cervical root avulsion injuries. Nerve root repair with C4-T1 hemilaminectomy was subsequently performed on 19 patients. The agreement between the two evaluative modalities with complete or incomplete lesions of ventral root and pre- or postganglionic lesions of dorsal root was measured for each root level. Both with ventral and dorsal root evaluation, C6, C7, and C8 yielded high agreement values, ranging from 86% to 94%. C5 manifested the lowest agreement values: 54% on ventral root assessment. Additionally, EMG, in comparison with MRI, revealed a higher quantity of implicated injured components. MRI, in turn, detected more lesion components than surgical exploration alone achieved. The capability of EMG to recognize axonotmesis leads to the discrepant findings between the two modalities. The visualization of mild neurotmesis by MRI, which cannot be achieved by surgical inspection, results in divergent findings between the two modalities. Both EMG and the MRI play crucial roles in preoperative assessment, and they may complement each other.

Human brain plasticity: an emerging view of the multiple substrates and mechanisms that cause cortical changes and related sensory dysfunctions after injuries of sensory inputs from the body

Injuries of peripheral inputs from the body cause sensory dysfunctions that are thought to be attributable to functional changes in cerebral cortical maps of the body. Prevalent theories propose that these cortical changes are explained by mechanisms that preeminently operate within cortex. This paper reviews findings from humans and other primates that point to a very different explanation, i.e. that injury triggers an immediately initiated, and subsequently continuing, progression of mechanisms that alter substrates at multiple subcortical as well as cortical locations. As part of this progression, peripheral injuries cause surprisingly rapid neurochemical/molecular, functional, and structural changes in peripheral, spinal, and brainstem substrates. Moreover, recent comparisons of extents of subcortical and cortical map changes indicate that initial subcortical changes can be more extensive than cortical changes, and that over time cortical and subcortical extents of change reach new balances. Mechanisms for these changes are ubiquitous in subcortical and cortical substrates and include neurochemical/molecular changes that cause functional alterations of normal excitation and inhibition, atrophy and degeneration of normal substrates, and sprouting of new connections. The result is that injuries that begin in the body become rapidly further embodied in reorganizational make-overs of the entire core of the somatosensory brain, from peripheral sensory neurons to cortex. We suggest that sensory dysfunctions after nerve, root, dorsal column (spinal), and amputation injuries can be viewed as diseases of reorganization in this core.

Accuracy of abnormal paraspinal muscle findings on contrast-enhanced MR images as indirect signs of unilateral cervical root-avulsion injury

PURPOSE

To evaluate the accuracy of abnormal magnetic resonance (MR) findings in the paraspinal muscles as indirect signs of nerve-root avulsion injury.

MATERIALS AND METHODS

Forty-three consecutive patients suspected of having unilateral root-avulsion injury underwent MR imaging and were evaluated. Paraspinal muscles were evaluated for abnormal signal intensity on T1- and T2-weighted images, abnormal enhancement on images obtained after contrast material enhancement, and muscle volume loss. MR images were interpreted independently by two observers for interobserver variability. MR findings were compared with findings of root continuity, determined with a combination of surgery and clinical evaluation. Sensitivities, specificities, and kappa values of the findings were calculated.

RESULTS

Sensitivities of MR findings in the paraspinal muscles indicating root-avulsion injury were 88% (36 of 41 patients) for abnormal enhancement, 83% (34 of 41 patients) for high signal intensity on T2-weighted images, 37% (15 of 41 patients) for high signal intensity on T1-weighted images, and 71% (29 of 41 patients) for muscle volume loss. Specificities for all findings were 100% (two of two patients). Of the paraspinal muscles, findings in the multifidus muscle were the most accurate and provided the highest interobserver agreement (kappa = 0.81).

CONCLUSION

Contrast material-enhanced abnormal MR findings in the paraspinal muscles are accurate in indicating root-avulsion injuries, and abnormal enhancement in the multifidus muscle is the most accurate among paraspinal muscle findings.

Imaging of adult brachial plexus traction injuries

Closed, high-energy transfer traction injuries of the adult brachial plexus lead to rupture or avulsion of the spinal nerves. Accurate preoperative diagnosis is crucial for surgical planning and reconstruction. Myelography, computerised tomographic myelography and magnetic resonance imaging are the main radiological methods for preoperative diagnosis of the lesion. This article reviews the current status of imaging of traction injuries of the adult brachial plexus.

Imaging the brachial plexus and peripheral nerves in infants and children

Imaging of the brachial plexus and peripheral nerves is challenging in the pediatric patient. Magnetic resonance imaging is the modality of choice as it is not invasive and demonstrates proximal and distal lesions. This may be used to detect nerve root avulsions, nerve ruptures, pseudo-meningoceles, brachial plexus scarring, post-traumatic neuromas, brachial plexus edema, spinal cord damage, abnormalities of the shoulder joint, trauma, neoplasms, and infection. Imaging allows diagnosis and careful preoperative evaluation of children suffering from brachial plexus injuries and peripheral nerve disorders.