. Introduction. Evaluation of the brachial plexus is a clinical challenge. Physical examination has traditionally been a mainstay in evaluating and localizing pathology involving the brachial plexus. Physical examination is especially difficult in patients with scarring and fibrosis secondary to surgery or irradiation.

Diagram of the brachial plexus. Thorough neurologic examination can be performed to localize the injury and to help the radiologist pinpoint the location of pathology. As the technology and resolution have improved, magnetic resonance imaging (MRI) has become increasingly important in the evaluation of brachial plexus pathology. Correlation of imaging results with electrophysiologic findings increases overall specificity and sensitivity.

3 , 4 , 5 . According to Nardin et al, 2 , 6 electromyelography (EMG) and MRI examinations are complementary. Their study demonstrated that the sensitivity of EMG and MRI were 72% and 60%, respectively. Plain radiography can depict large lesions affecting the brachial plexus. However, radiographs are far less sensitive than other studies. Computed tomography (CT) scanning has increased sensitivity for depicting extrinsic masses that compress the nerves; however, it offers poor soft tissue contrast for direct evaluation of the nerves.

With the advent of MRI, nerves that compose the brachial plexus can now be directly evaluated. Intrinsic and extrinsic pathology can be evaluated. Exact anatomic components of the brachial plexus, such as the roots, trunks, divisions, and cords, can be identified. MRI has the additional benefit of multiplanar imaging and increased soft tissue contrast. The tissue resolution of MRI is constantly improving with new pulse sequences and coil designs.

1 , 6 , 7 , 8 , 9 , 10 , 11 (See the images below.)

Sagittal image of the brachial plexus shows an area of increased signal intensity in the C6 neural foramen.

12 With MRI, the nerve can be directly visualized and evaluated for pathology. MRI sequences such as fat-saturated T2-weighted spin-echo, short-tau inversion recovery (STIR), and gadolinium-enhanced T1-weighted spin-echo sequences help in depicting subtle changes in the signal intensity of the nerves or enhancement and aid in refining the differential diagnosis.

For more information, see the eMedicine topic Nephrogenic Systemic Fibrosis. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness.

For more information, see Medscape | Technique and Imaging Parameters. The brachial plexus can be easily identified on MRI by first identifying the anterior scalene muscle. The brachial plexus and subclavian artery (relationship outlined above) are deep to the anterior scalene. Normal components of the brachial plexus have low signal intensity on images obtained with all sequences and are surrounded by fat.

The roots are best seen on axial images, whereas the remaining components are well seen on coronal and sagittal images.

A surface coil provides resolution higher than that of a body coil, but it increases artifact due to respiratory motion. A combination of each may be used in sequences for the brachial plexus.

. [ CLOSE WINDOW ].. . References. . Sureka J, Cherian RA, Alexander M, Thomas BP. MRI of brachial plexopathies. Clin Radiol. Feb 2009;64(2):208-18. [Medline] | Nardin RA, Patel MR, Gudas TF, et al. Electromyography and magnetic resonance imaging in the evaluation of radiculopathy. Muscle Nerve.

Jul-Aug 2000;20(4):1023-32. [Medline] |.. . Iyer RB, Fenstermacher MJ, Libshitz HI. MR imaging of the treated brachial plexus. AJR Am J Roentgenol. Jul 1996;167(1):225-9. [Medline] | van Gelein Vitringa VM, van Kooten EO, Mullender MG, van Doorn-Loogman MH, van der Sluijs JA. An MRI study on the relations between muscle atrophy, shoulder function and glenohumeral deformity in shoulders of children with obstetric brachial plexus injury.

J Brachial Plex Peripher Nerve Inj.

Hof JJ, Kliot M, Slimp J, Haynor DR. What's new in MRI of peripheral nerve entrapment'.

Top Magn Reson Imaging. . Qin B, Gu L, Liu X, Zhang Z, Xiang J, Wang H, et al. [Value of MRI in diagnosis of obstetrical brachial plexus palsy pre-ganglionic injury]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. Dec 2008;22(12):1455-7. [Medline] | Doi K, Otsuka K, Okamoto Y, et al. Cervical nerve root avulsion in brachial plexus injuries: magnetic resonance imaging classification and comparison with myelography and computerized tomography myelography.

J Neurosurg Spine. Apr 2002;96(3):277-84. [Medline] |.. . Nath RK, Humphries AD. Computed tomography of the shoulders in patients with obstetric brachial plexus injuries: a retrospective study. Ann Surg Innov Res. Nov 7 2008;2:4. [Medline] |.. Takahara T, Hendrikse J, Yamashita T, Mali WP, Kwee TC, Imai Y, et al. Diffusion-weighted MR neurography of the brachial plexus: feasibility study.

Radiology.

Sudhakar R Satti, MD, Director Neurointerventional Radiology, Department of Diagnostic and Interventional Radiology, Albert Einstein Medical Center. Coauthor(s). Christopher Cerniglia, DO, ME, Interim Director, Division of Musculoskeletal Imaging, UMass Memorial Medical Center, Assistant Professor, Department of Radiology, University of Massachusetts School of Medicine. Christopher Cerniglia, DO, ME is a member of the following medical societies: American College of Radiology , American Osteopathic Association , American Roentgen Ray Society , and Radiological Society of North America .

Ajit Belliappa, MD, Staff Physician, Doshi Diagnostic, Midwood Branch. Ajit Belliappa, MD is a member of the following medical societies: American College of Radiology , Phi Beta Kappa , and Radiological Society of North America . Steven P Meyers, MD, PhD, Professor, Department of Radiology/Imaging Sciences and Neurosurgery, University of Rochester Medical Center. Steven P Meyers, MD, PhD is a member of the following medical societies: American College of Radiology , American Roentgen Ray Society , American Society of Head and Neck Radiology , American Society of Neuroradiology , Children's Oncology Group , International Society for Magnetic Resonance in Medicine , and Radiological Society of North America .

Disclosure: Nothing to disclose

Medical Editor. Barton F Branstetter IV, MD, Associate Professor of Radiology, Otolaryngology, and Biomedical Informatics, University of Pittsburgh; Director of Head and Neck Imaging, Clinical Director of Neuroradiology, Department of Radiology, Division of Neuroradiology, University of Pittsburgh Medical Center.

C Douglas Phillips, MD, Director of Head and Neck Imaging, Division of Neuroradiology, Weill Medical College of Cornell University/New York Presbyterian Hospital.

Robert M Krasny, MD, Resolution Imaging Medical Corporation.

Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington.

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