MR imaging of the brachial plexus: current imaging sequences, normal findings, and findings in a spectrum of focal lesions with MR-pathologic correlation

Surgical resection of superior pulmonary sulcus tumor after neoadjuvant chemoradiation via the anterior transmanubrial approach: a case report

Superior pulmonary sulcus tumor is a cancer arising in the apex of the lung that with potential invasion of the brachial plexus, upper ribs, vertebrae, subclavian vessels, and stellate ganglion. Induction concurrent chemoradiotherapy followed by radical surgical resection with lobectomy combined with any structures in the thoracic inlet invaded by tumor and thorough mediastinal lymph node dissection is the preferred treatment. Both anterior and posterior approaches are applied for resection. Here, we report a 61-year-old man with an 8.6 cm × 5.1 cm mass arising from the right upper lobe invading the apex of the chest wall. Brachial plexus magnetic resonance imaging suggested tumor invasion of the inferior trunk of the brachial plexus, anterior portion of the first 2 ribs, and suspicious involvement of the subclavian artery. Biopsy of the mass showed stage cT4N2M0, IIIB, poorly differentiated adenocarcinoma. The patient was treated by induction concurrent chemoradiotherapy, which was followed by surgical resection of the right upper lobe and the affected chest wall via the transmanubrial approach. The patient suffered prolonged postoperative air leak and empyema. After continuous chest tube drainage and intrapleural fibrinolytic therapy, he recovered well and was discharged safely. Final pathology showed no viable residue tumor, pathologic complete response of the tumor to induction treatment, a tumor size of 4.1 cm, and no lymph nodes; therefore, the final stage was ypT0N0M0. The transmanubrial approach is feasible for resection of tumor invading the branches of the subclavian artery; however, postoperative empyema which might have resulted from prolonged air leak should be carefully treated by meticulous air leak management.

Imaging of non-neurogenic peripheral nerve malignancy-a case series and systematic review

OBJECTIVE

To evaluate the frequency, clinico-pathologic and imaging features of malignant tumors in peripheral nerves which are of non-neurogenic origin (non-neurogenic peripheral nerve malignancy-PNM).

MATERIALS AND METHODS

We retrospectively reviewed our pathology database for malignant peripheral nerve tumors from 07/2014-07/2019 and performed a systematic review. Exclusion criteria were malignant peripheral nerve sheath tumor (MPNST). Clinico-pathologic and imaging features, apparent diffusion coefficient (ADC_min), and standard uptake values (SUV_max) are reported.

RESULTS

After exclusion of all neurogenic tumors (benign = 196, MPNST = 57), our search yielded 19 non-neurogenic PNMs (7%, n = 19/272), due to primary intraneural malignancy (16%, n = 3/19) and secondary perineural invasion from an adjacent malignancy (16%, n = 3/19) or metastatic disease (63%, n = 12/19). Non-neurogenic PNMs were located in the lumbosacral plexus/sciatic nerves (47%, n = 9/19), brachial plexus (32%, n = 6/19), femoral nerve (5%, n = 1/19), tibial nerve (5%, n = 1/19), ulnar nerve (5%, n = 1/19), and radial nerve (5%, n = 1/19). On MRI (n = 14/19), non-neurogenic PNM tended to be small (< 5 cm, n = 10/14), isointense to muscle on T1-W (n = 14/14), hyperintense on T2-WI (n = 12/14), with enhancement (n = 12/12), low ADC_min (0.5-0.7 × 10-3 mm²/s), and variable metabolic activity (SUV_max range 2.1-13.1). A target sign was absent (n = 14/14) and fascicular sign was rarely present (n = 3/14). Systematic review revealed 89 cases of non-neurogenic PNM.

CONCLUSION

Non-neurogenic PNMs account for 7% of PNT in our series and occur due to metastases and primary intraneural malignancy. Although non-neurogenic PNMs exhibit a non-specific MRI appearance, they lack typical signs of neurogenic tumors such as the target sign. Quantitative imaging features identified by DWI (low ADC) and F¹⁸-FDG PET/CT (high SUV) may be helpful clues to the diagnosis.

Pancoast's syndrome caused by lymph node metastasis from breast cancer

Pancoast's syndrome may be the result of neoplastic, inflammatory or infectious disease. We report an unusual case of Pancoast's syndrome in a patient with metastatic breast cancer. A 54-year-old woman, affected by metastatic breast cancer, presented for severe shoulder pain, paraesthesia and numbness in the right arm. Despite further multiple lines of systemic chemotherapy, she developed a progressive enlargement of retropectoral, supraclavicular and infraclavicular lymph node metastases, which involved brachial plexus, apex of lung and anterior mediastinum. Physical examination revealed severe weakness of proximal muscles of the right arm. Neuropathic pain was managed with pharmacological treatment. Lastly, the patient has been treated with intrathecal analgesia with morphine and ziconotide with a good control of pain. The patient died after 3 months.

Accuracy of MRI in diagnosing peripheral nerve disease: a systematic review of the literature

OBJECTIVE

MRI is increasingly being used to evaluate extracranial peripheral nerve disease in clinical practice. The objective of this study was to systematically review the accuracy of MRI in distinguishing normal from abnormal extracranial peripheral nerves.

CONCLUSION

There is significant heterogeneity between studies investigating the accuracy of MRI. Studies have shown that nerve T2-weighted or STIR hyperintensity, nerve enlargement, and nerve flattening are associated with peripheral nerve disease.

Hemangiomas of the brachial plexus: a case series

OBJECTIVE

Hemangiomas of the brachial plexus are very rare, and there has not been a collection of multiple cases published in the literature to date. Extraneural brachial plexus hemangiomas typically present with similar signs and symptoms as nerve sheath tumors, including pain, paresthesia, and occasionally weakness, in addition to nonspecific imaging findings, making their diagnosis difficult. Exploratory surgery can lead to significant bleeding and nerve injury when a hemangioma or an associated aneurysm is encountered intraoperatively. We present 5 cases of extraneural hemangiomas causing brachial plexopathy, including pre-, intra-, and postoperative decision making, with an emphasis on diagnostic and management issues as well as outcomes.

METHODS

A retrospective review was performed of 5 patients who underwent surgery at a university teaching hospital between 1995 and 2007 for exploration of brachial plexus lesions that were confirmed to be hemangiomas at pathological examination.

RESULTS

All 5 patients presented with findings on history, physical examination, imaging, and electromyography suggesting a diagnosis of nerve sheath tumor. Two patients had biopsies (1 needle, 1 open), both of which were nondiagnostic. Three patients underwent digital subtraction angiography with successful preoperative embolization. Each patient had a complete or a radical subtotal tumor resection, and all were intact neurologically after surgical resection. Pathological evaluation identified 3 venous hemangiomas, 1 hemangioma with arteriovenous malformation features, and 1 Masson hemangioma associated with a large aneurysm.

CONCLUSION

Extraneural hemangiomas of the brachial plexus are very rare, but a high index of suspicion and appropriate preoperative evaluation, including angiography with the option for embolization, can result in decreased intraoperative hemorrhage and better patient outcomes.

Magnetic resonance imaging characteristics of peripheral nerve sheath tumors of the canine brachial plexus in 18 dogs

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.

Spatial mapping of the brachial plexus using three-dimensional ultrasound

Imaging of the brachial plexus with MRI and standard two-dimensional (2D) ultrasound has been reported, and 2D ultrasound-guided regional anaesthetic block is an established technique. The aim of this study was to map the orientation of the brachial plexus in relation to the first rib, carotid and subclavian arteries, using three-dimensional (3D) ultrasound. A free-hand optically tracked 3D ultrasound system was used with a 12 MHz transducer. 10 healthy volunteers underwent 3D ultrasound of the neck. From the 3D ultrasound data sets, the outlines of the brachial plexus, subclavian artery and first rib were manually segmented. A surface was interpolated from the series of outlines to produce a spatially orientated 3D reconstruction of the brachial plexus. The brachial plexus could be mapped in all volunteers, although a variation in image resolution between individuals existed. Anatomical variations were demonstrated between the 10 volunteers; the most notable and clinically relevant was the alignment of the plexus divisions. 3D reconstructions illustrated the plexus, changing its orientation from a vertical alignment in the interscalene region to a more horizontal alignment in the supraclavicular fossa. Spatial mapping of the brachial plexus is possible with 3D ultrasound using the subclavian artery and first rib as landmarks. There is a deviation from the conventionally described anatomy and this may have implications for the administration of regional anaesthesia.

Metastases to the peripheral nervous system

Cancer metastasis can affect any part of the nervous system. When the peripheral nervous system is involved, the usual targets are cranial nerves, nerve roots and plexi. However, peripheral nerves and muscles can also be affected by compression or infiltration of neoplastic cells. This review focuses in the diagnosis and treatment of metastatic complications of cancer involving plexi, peripheral nerves and muscles.

MR imaging of brachial plexus

The brachial plexus is a complex anatomic component originating from ventral rami of the lower cervical nerve roots from C5 to C8 and upper thoracic spinal nerve roots from T1, providing sensory and motor innervation to the upper extremities. As it is inaccessible to palpation, clinical evaluation of the brachial plexus is very challenging and localizing lesions along its course is very difficult. The gamut of pathologic conditions involving the brachial plexus includes primary tumor, direct extension of adjacent tumor, metastasis, trauma, or an inflammatory condition. MR imaging provides superior diagnostic ability due to its ability of multiplanar imaging and greater soft tissue contrast. This article discusses MR imaging findings in a variety of pathologic conditions, with special emphasis on neoplastic process.