Differentiation of Pre- and Postganglionic Nerve Injury Using MRI of the Spinal Cord

Radiofrequency stimulation of the dorsal root ganglion as a diagnostic tool for radicular pain syndromes: six representative cases

BACKGROUND

We discuss the diagnostic benefit of pulsed radiofrequency (PRF) of the dorsal root ganglion (DRG) in a case series of patients with different pathologies. We expand the diagnostic potential of DRG stimulation beyond paresthesia mapping by using DRG stimulation to help determine the role of the DRG in the patient's pain and narrow down the etiology. In some cases, DRG stimulation was also part of the treatment plan.

METHODS

Six patients underwent DRG radiofrequency as a diagnostic/therapeutic step before considering implantation of a DRG neurostimulator. First, patients underwent a basic bedside neurological evaluation. Next, an electrode was placed in the epidural space through the sacral hiatus or between vertebral laminae. Then, sensory stimulation was applied at 50 Hz and gradually increased from 0.1 V until the patient reported paresthesia or until a maximum intensity of 2 V was reached. Patients were asked to describe where the stimulation was felt and outline the anatomical area the paresthesia covered. Then a motor stimulation was applied at 2 Hz until muscle twitching was reported by the patient or observed by the physician.

RESULTS

The information obtained helped diagnose the type of lesion as principally preganglionic, ganglionic, or postganglionic. This information guided patient management.

CONCLUSION

PRF of the DRG can provide valuable diagnostic information and is a useful step before ganglionic electrode implantation. In all cases, PRF of the DRG provided valuable diagnostic information and guided management options.

Traumatic Brachial Plexus Root Avulsion With Pseudomeningocele: A Case Series

Traumatic avulsion pseudomeningocele of the brachial plexus is an uncommon and challenging condition with particular diagnostic and treatment challenges. This case series intends to investigate the unusual consequences of brachial plexus damage, emphasizing the significance of surgical procedures and rehabilitation strategies. Three cases of traumatic avulsion pseudomeningocele with medical histories, imaging studies, procedures, and recovery plans were carefully examined. The rehabilitation approaches and surgical procedures are outlined in detail. Each case had its own unique set of difficulties and complications. Nerve grafting and pseudomeningocele repair surgery were performed. The outcomes were evaluated based on neurological examination, range of motion, sensory recovery, and patient reports. Only a few patients showed discernible improvements in their quality of life, motor function, and discomfort. In this case series, we highlight the people with traumatic avulsion pseudomeningocele of the brachial plexus and recount their inspiring journeys. Surgical procedures and rehabilitation approaches have produced favorable outcomes regarding recovering functionality and enhancing patients' general well-being. These results highlight the value of interdisciplinary partnerships and individualized strategies in treating this uncommon illness. Further, more profound research and long-term follow-up are required regarding the condition and optimizing the treatment methods for this challenging clinical entity.

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.

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

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

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

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MRI helps to determine the extent of the infection.

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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.

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

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MRI of the brachial plexus should include cervical spine MRI.

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Spinal nerve root absence is seen in preganglionic injuries.

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

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Appropriate MRI rapport is crucial in communication with the clinician.

Diffusion Tensor Imaging for Diagnosing Root Avulsions in Traumatic Adult Brachial Plexus Injuries: A Proof-of-Concept Study

Cross-sectional MRI has modest diagnostic accuracy for diagnosing traumatic brachial plexus root avulsions. Consequently, patients either undergo major exploratory surgery or months of surveillance to determine if and what nerve reconstruction is needed. This study aimed to develop a diffusion tensor imaging (DTI) protocol at 3 Tesla to visualize normal roots and identify traumatic root avulsions of the brachial plexus. Seven healthy adults and 12 adults with known (operatively explored) unilateral traumatic brachial plexus root avulsions were scanned. DTI was acquired using a single-shot echo-planar imaging sequence at 3 Tesla. The brachial plexus was visualized by deterministic tractography. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated for injured and avulsed roots in the lateral recesses of the vertebral foramen. Compared to healthy nerves roots, the FA of avulsed nerve roots was lower (mean difference 0.1 [95% CI 0.07, 0.13]; p < 0.001) and the MD was greater (mean difference 0.32 × 10-3 mm2/s [95% CI 0.11, 0.53]; p < 0.001). Deterministic tractography reconstructed both normal roots and root avulsions of the brachial plexus; the negative-predictive value for at least one root avulsion was 100% (95% CI 78, 100). Therefore, DTI might help visualize both normal and injured roots of the brachial plexus aided by tractography. The precision of this technique and how it relates to neural microstructure will be further investigated in a prospective diagnostic accuracy study of patients with acute brachial plexus injuries.

Pseudomeningocele From Brachial Plexus Root Avulsion

We report a case of a 42-year-old male involved in a motor vehicle accident. Initial MRI revealed T2 hypo-intensity of the anterior cord at the C6 level of the cervical spine which raised significant discussions within the neurosurgical, radiology and ICU departments at our institution. After careful review of images and patient’s clinical examination we suspected root avulsion of the brachial plexus. Subsequent MRI brachial plexus showed a large axillary pseudomeningocele originating from the C5-T2 nerve roots. Our team concluded the patient suffered a complete brachial plexus injury from right lateral hyperflexion as extrapolated from his injuries. The aim of this report is to highlight the uncommon condition and report of key clinical findings and management strategies.

Magnetic resonance imaging for detecting root avulsions in traumatic adult brachial plexus injuries: protocol for a systematic review of diagnostic accuracy

BACKGROUND

Adult brachial plexus injuries (BPI) are becoming more common. The reconstruction and prognosis of pre-ganglionic injuries (root avulsions) are different to other types of BPI injury. Preoperative magnetic resonance imaging (MRI) is being used to identify root avulsions, but the evidence from studies of its diagnostic accuracy are conflicting. Therefore, a systematic review is needed to address uncertainty about the accuracy of MRI and to guide future research.

METHODS

We will conduct a systematic search of electronic databases alongside reference tracking. We will include studies of adults with traumatic BPI which report the accuracy of preoperative MRI (index test) against surgical exploration of the roots of the brachial plexus (reference standard) for detecting either of the two target conditions (any root avulsion or any pseudomeningocoele as a surrogate marker of root avulsion). We will exclude case reports, articles considering bilateral injuries and studies where the number of true positives, false positives, false negatives and true negatives cannot be derived. The methodological quality of the included studies will be assessed using a tailored version of the QUADAS-2 tool. Where possible, a bivariate model will be used for meta-analysis to obtain summary sensitivities and specificities for both target conditions. We will investigate heterogeneity in the performance of MRI according to field strength and the risk of bias if data permits.

DISCUSSION

This review will summarise the current diagnostic accuracy of MRI for adult BPI, identify shortcomings and gaps in the literature and so help to guide future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016049702 .