Imaging the anatomy of the brachial plexus: review and self-assessment module

A Neglected Cause of Iatrogenic Brachial Plexus Injuries in Psychiatric Patients

BACKGROUND

Psychiatric patients are often kept immobilized during hospitalization to avoid self-inflicted injuries and danger to third parties. Inadequate positioning can lead to brachial plexus injuries (BPI).

OBJECTIVE

To present a series of 5 psychiatric patients with BPI after being left sedated and restrained for prolonged periods of time during hospitalization.

METHODS

We retrospectively reviewed the charts of 5 psychiatric patients with iatrogenic BPI referred by other institutions to our service. The restraint technique adopted by those institutions consisted of a high-thoracic restraint. All patients underwent complete clinical and neurological examination at our center. Information concerning patient demographics, BPI characteristics, treatment choice, and ultimate outcome was recorded.

RESULTS

Three patients were male. The age of our patients ranged from 25 to 61 years old (mean: 41.2; median: 43). Three patients had a diagnosis of bipolar disorder while 2 had schizophrenia. Duration of immobilization ranged from 5 to 168 h (mean: 77.8; median: 72). Four patients presented with a unilateral right-sided lesion. Time to presentation ranged from 1 to 9 mo (mean: 4.2; median: 4). All patients also had intense pain and axillary lesions. Four patients received conservative treatment with partial or full functional recovery and complete pain resolution. The remaining patients underwent surgical repair and experienced good functional outcome.

CONCLUSION

Psychiatric patients who need to be sedated and immobilized must be monitored closely, as BPI can occur from high-thoracic restraints. When such an injury occurs, the patient must be referred to a center specialized in peripheral nerve surgery and rehabilitation.

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

Brachial plexus injury (BPI) is a devastating type of nerve injury, potentially causing loss of motor and sensory function. Principally, BPI is either categorized as preganglionic or postganglionic, with the early establishment of injury level being crucial for choosing the correct treatment strategy. Despite diagnostic advances, the need for a reliable, non-invasive method for establishing the injury level remains. We studied the usefulness of in vivo magnetic resonance imaging (MRI) of the spinal cord for determination of injury level. The findings were related to neuronal and glial changes. Rats underwent unilateral L4 & L5 ventral roots avulsion or sciatic nerve axotomy. The injuries served as models for pre- and postganglionic BPI, respectively. MRI of the L4/L5 spinal cord segments 4 weeks after avulsion showed ventral horn (VH) shrinkage on the injured side compared to the uninjured side. Axotomy induced no change in the VH size on MRI. Following avulsion, histological sections of L4/L5 revealed shrinkage in the VH grey matter area occupied by NeuN-positive neurons, loss of microtubular-associated protein-2 positive dendritic branches (MAP2), pan-neurofilament positive axons (PanNF), synaptophysin-positive synapses (SYN) and increase in immunoreactivity for the microglial OX42 and astroglial GFAP markers. Axotomy induced no changes in NeuN-reactivity, modest decrease of MAP2 immunoreactivity, no changes in SYN and PanNF labelling, and a modest increase in OX42 and SYN labeling. Histological and radiological findings were congruent when assessing changes after axotomy, while MRI somewhat underestimated the shrinkage. This study indicates a potential diagnostic value of structural spinal cord MRI following BPI.

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

Three-dimensional diffusion-weighted steady-state free precession (3D DW-SSFP) of high-resolution magnetic resonance has emerged as a promising method to visualize the peripheral nerves. In this study, the application value of 3D DW-SSFP brachial plexus imaging in the diagnosis of brachial plexus injury (BPI) was investigated. 33 patients with BPI were prospectively examined using 3D DW-SSFP MR neurography (MRN) of brachial plexus. Results of 3D DW-SSFP MRN were compared with intraoperative findings and measurements of electromyogram (EMG) or somatosensory evoked potentials (SEP) for each injured nerve root. 3D DW-SSFP MRN of brachial plexus has enabled good visualization of the small components of the brachial plexus. The postganglionic section of the brachial plexus was clearly visible in 26 patients, while the preganglionic section of the brachial plexus was clearly visible in 22 patients. Pseudomeningoceles were commonly observed in 23 patients. Others finding of MRN of brachial plexus included spinal cord offset (in 16 patients) and spinal cord deformation (in 6 patients). As for the 3D DW-SSFP MRN diagnosis of preganglionic BPI, the sensitivity, the specificity and the accuracy were respectively 96.8%, 90.29%, and 94.18%. 3D DW-SSFP MRN of brachial plexus improve visualization of brachial plexus and benefit to determine the extent of injury.

Use of chemical shift encoded magnetic resonance imaging (CSE-MRI) for high resolution fat-suppressed imaging of the brachial and lumbosacral plexuses

PURPOSE

In the era of increasingly complex surgical techniques for peripheral nerve repair, there is a need for high spatial resolution imaging of the neural plexuses in the body. We describe our experience with chemical shift encoded MRI and its implications for patient management.

MATERIALS AND METHODS

IDEAL water-fat separation is a chemical shift based method of homogeneously suppressing signal from fat, while maintaining adequate signal. This technique was used in clinical practice and the patient images reviewed.

RESULTS

IDEAL water-fat separation was shown to improve visualization of the brachial and lumbosacral plexuses with good fat suppression and high signal to noise ratio.

CONCLUSION

IDEAL water - fat separation is an excellent technique to use in the imaging of the brachial and lumbosacral plexuses as it balances the need for homogeneous fat suppression with maintenance of excellent signal to noise ratio.

Independent learning modules enhance student performance and understanding of anatomy

Didactic lessons are only one part of the multimodal teaching strategies used in gross anatomy courses today. Increased emphasis is placed on providing more opportunities for students to develop lifelong learning and critical thinking skills during medical training. In a pilot program designed to promote more engaged and independent learning in anatomy, self-study modules were introduced to supplement human gross anatomy instruction at Joan C. Edwards School of Medicine at Marshall University. Modules use three-dimensional constructs to help students understand complex anatomical regions. Resources are self-contained in portable bins and are accessible at any time. Students use modules individually or in groups in a structured self-study format that augments material presented in lecture and laboratory. Pilot outcome data, measured by feedback surveys and examination performance statistics, suggest that the activity may be improving learning in gross anatomy. Positive feedback on both pre- and post-examination surveys showed that students felt the activity helped to increase their understanding of the topic. In concordance with student perception, average examination scores on module-related laboratory and lecture questions were higher in the two years of the pilot program compared with the year before its initiation. Modules can be fabricated on a modest budget using minimal resources, making implementation practical for smaller institutions. Upper level medical students assist in module design and upkeep, enabling continuous opportunities for vertical integration across the curriculum. This resource offers a feasible mechanism for enhancing independent and lifelong learning competencies, which could be a valuable complement to any gross anatomy curriculum.

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.

Pancoast tumor: the role of magnetic resonance imaging

We report imaging techniques in the definition of the therapeutic planning of a 65-year-old man with a diagnosis of Pancoast tumor. Computed Tomography has a pivotal role in the assessment of nodes involvement and distant metastasis. Magnetic Resonance allows a detailed study of locoregional extension for its high soft tissue resolution. We particularly highlight the actual importance of Magnetic Resonance Neurography, Diffusion-Weighted Imaging, and Magnetic Resonance Angiography techniques in the assessment of the superior sulcus vascular and nervous structures involvement. Their integrity has been showed in our patient with a complete surgical excision of the lesion.

Diagnosis of brachial and lumbosacral plexus lesions

To most doctors, brachial and lumbosacral plexopathies are known as difficult disorders, because of their complicated anatomy and relatively rare occurrence. Both the brachial, lumbar, and sacral plexuses are extensive PNS structures stretching from the neck to axillary region and running in the paraspinal lumbar and pelvic region, containing 100000-200000 axons with 12-15 major terminal branches supplying almost 50 muscles in each limb. The most difficult part in diagnosing a plexopathy is probably that it requires an adequate amount of clinical suspicion combined with a thorough anatomical knowledge of the PNS and a meticulous clinical examination. Once a set of symptoms is recognized as a plexopathy the patients' history and course of the disorder will often greatly limit the differential diagnosis. The most common cause of brachial plexopathy is probably neuralgic amyotrophy and the most common cause of lumbosacral plexopathy is diabetic amyotrophy. Traumatic and malignant lesions are fortunately rarer but just as devastating. This chapter provides an overview of both common and rarer brachial and lumbosacral plexus disorders, focusing on clinical examination, the use of additional investigative techniques, prognosis, and treatment.

Malignant brachial plexopathy: A pictorial essay of MRI findings

For imaging, the brachial plexus is a technically and anatomically challenging region of the peripheral nervous system. MRI has a central role in the identification and accurate characterization of malignant lesions arising here, as also in defining their extent and the status of the adjacent structures. The purpose of this pictorial essay is to describe the MRI features of primary and secondary malignant brachial plexopathies and radiation-induced brachial nerve damage.

MR imaging findings in brachial plexopathy with thoracic outlet syndrome

The BPL is a part of the peripheral nervous system. Many disease processes affect the BPL. In this article, on the basis of 60 patients, we reviewed MR imaging findings of subjects with brachial plexopathy. Different varieties of BPL lesions are discussed.

Aspects cliniques, électroneuromyographiques et IRM des traumatismes du plexus brachial

OBJECTIVES

Management of traumatic lesions of the brachial plexus mainly depends on whether the injury is pre- (nerve root avulsion) or postganglionic (trunks and cords). The aim of this study was to assess the diagnostic and prognostic value of MRI in such lesions, and to determine any correlations among radiological, clinical and electroneuromyographical (EMG) data from both the initial and follow-up studies.

MATERIAL AND METHODS

Nine patients with acute traumatic lesions of the brachial plexus were investigated by MRI and EMG. Five further patients served as controls. The MRI protocol included fast spin-echo (FSE) T2-weighted and STIR sequencing. These scans were independently interpreted by two senior radiologists. Their findings were then validated during consensus meetings of surgeons, radiologists and neurologists to identify the exact localization and mechanism of each lesion, and to determine the advantages and drawbacks of each technique.

RESULTS

Among the nine patients, MRI scans were judged as normal in three whereas EMG showed distal lesions in two of them. In a further three patients, STIR MRI sequences demonstrated high signal intensities from the trunks and cords of C5 to T1. Among these three patients, MRI at three months showed persistence of these signal anomalies in one patient, and partial regression in the two others. In the remaining three patients, three-dimensional T2-weighted sequences showed nerve root avulsion, consistent with the initial EMG findings.

CONCLUSION

MRI is the best technique to demonstrate nerve root avulsion. However, unlike EMG, MRI does not allow visualization of distal lesions of the brachial plexus. Differentiation between edema (reversible) and demyelination (irreversible) of trunk and cord lesions remains difficult, and requires EMG or late MRI.