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Magnetic Resonance Neurography Diagnosed Brachial Plexitis: A Case Report Selda Sarikaya, MD, Murat Sumer, MD, S¸enay Özdolap, MD, C. Zuhal Erdem, MD ABSTRACT. Sarikaya S, Sumer M, Özdolap S, Erdem CZ. Magnetic resonance neurography diagnosed brachial plexitis: a case report. Arch Phys Med Rehabil 2005;86:1058-9. Idiopathic brachial plexitis is a rare disorder presenting with pain and weakness in the shoulder girdle and upper extremity. Idiopathic brachial plexitis can mimic other conditions that cause acute pain and weakness around the shoulder, and its diagnosis can be challenging. There is no special test for the diagnosis of idiopathic brachial plexitis, although electromyography may be useful. In this case of idiopathic brachial plexitis, we present magnetic resonance neurography findings for the first time. Key Words: Brachial plexus neuritis; Case report; Magnetic resonance imaging; Rehabilitation. © 2005 by American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation DIOPATHIC BRACHIAL PLEXITIS is an uncommon neuIderrologic syndrome characterized by the acute onset of shouland arm pain followed by weakness, sensory loss, and atrophy. The annual incidence of disease has been estimated at 1.64 cases per 100,000 persons.1 Idiopathic brachial plexitis can mimic numerous other conditions that cause acute pain and weakness around the shoulder, such as cervical disk disease, rotator cuff tears, and impingement syndromes; tumors of the spinal cord or brachial plexus; and compressive nerve injuries.2,3 The diagnosis of idiopathic brachial plexitis mainly rests on the clinical history and examination, but additional investigations are needed to confirm the diagnosis. The most useful methods are electrophysiologic4 and radiologic studies.3,5,6 Magnetic resonance imaging (MRI) studies of the brachial plexus and cervical spinal cord are generally unremarkable, although signal changes and atrophy in the involved muscles can be found.3,7 Magnetic resonance neurography (MRN) is a new technique for the evaluation of peripheral nerve disorders.8,9 To our knowledge, there is no published literature on MRN findings of the idiopathic brachial plexitis. Herein we report MRN findings of a patient presenting with isolated posterior cord involvement.
From the Departments of Physical Medicine and Rehabilitation (Sarikaya, Özdolap), Neurology (Sumer), and Radiodiagnostic (Erdem), Zonguldak Karaelmas University, School of Medicine, Zonguldak, Turkey. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated. ¨ niversitesi Tıp Reprint requests to Selda Sarikaya, MD, Zonguldak Karaelmas U Fakültesi, Fiziksel Tip ve Rehabilitasyon AD, 67000 Zonguldak, Turkey, e-mail:
[email protected]. 0003-9993/05/8605-8906$30.00/0 doi:10.1016/j.apmr.2004.08.003
Arch Phys Med Rehabil Vol 86, May 2005
CASE DESCRIPTION A man in his late thirties was admitted with severe pain and weakness of his left arm. He had had weakness for about 1 year. There was no history of trauma, viral or bacterial infection, or vaccination. On physical examination, he had marked atrophy of the left deltoid and triceps muscles. He also had weakness of the left deltoid (grade 4/5), triceps (grade 3/5), biceps (grade 4/5), and wrist extensor muscles (grade 4/5). He had no sensory deficit. The left biceps and brachioradial reflexes were normal, but the left triceps reflex was absent. His cervical vertebrae radiographs showed only mild decrease of the cervical lordosis. MRI of the brachial plexus and cervical spinal cord did not show any nerve compression on his left side. The results of the complete blood count, erythrocyte sedimentation rate, serum electrolytes, glucose, albumin, globuline, blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, thyroid hormone levels, protein electrophoresis, and blood film were normal. Electrodiagnostic tests were performed. Electrodiagnostic studies showed normal motor conduction velocities in the left median, ulnar, and radial nerves, including normal median and ulnar F latencies. Sensory nerve conduction studies showed a low sensory nerve action potential (SNAP) amplitude in the left ulnar nerve. A SNAP amplitude for the left median sensory nerve was unobtainable. Needle electromyography examination showed fibrillation potentials, positive sharp waves, and an increased proportion of polyphasic, prolonged duration, and high amplitude motor unit potentials in the left deltoid, triceps, and extensor digitorum communis muscles. Recruitment showed an incomplete interference pattern in the left triceps and extensor digitorum communis muscles and a single unit interference pattern in the left deltoid muscle. Normal duration and amplitude motor unit potentials were recorded from the left biceps, the thenar and hypothenar muscles, the supraspinatus, and the cervical paraspinal muscles. MRN was performed with 1.5T MR System,a using the surface coil for signal reception. Imaging sequences included a coronal T1-weighted conventional spin echo (repetition time [TR], 700ms; echo time [TE], 20ms) sequences and axial and coronal short tau inversion recovery (STIR) (TR, 5000ms; TE, 52ms; time inversion, 160ms; number of excitations, 2; field of view, 18⫻18cm; slice thickness, 3mm, 6mm) sequences. Flow suppression was used to minimize the effects of flow enhancement in blood vessels. MRN of the left brachial plexus showed increased signal intensity in the posterior cord (fig 1). According to clinical, physical, electrophysiologic, and radiologic findings, brachial plexitis was diagnosed. DISCUSSION Idiopathic brachial plexitis was first reported by Feinberg in 1897.10 Various terms have been ascribed to it, such as brachial plexus neuropathy, acute brachial plexitis, acute shoulder neuritis, and Parsonage-Turner syndrome. The pathophysiology of disease is unknown; however, the condition generally is thought to be an immune-mediated inflammatory reaction. Various events or factors can precipitate the condition, such as
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shows promise for the future. MRN, with its higher resolution and imaging quality, should be used first in the diagnosis of idiopathic brachial plexitis, which is the most challenging issue in peripheral nerve disorders. Further studies are necessary to analyze the sensitivity and specificity of this technique.
Fig 1. Coronal STIR image showing increased signal intensity in the posterior cord of the left brachial plexus (arrow).
trauma, infection, viral disease, heavy exercise, surgery, immunization, and autoimmune mechanism.2,4,11-13 The most common symptom is an acute-onset severe pain in the shoulder girdle. The pain generally radiates from the shoulder to the upper arm or neck. Patients usually have weakness after the pain subsides. Weakness commonly occurs in the deltoid, supraspinatus, infraspinatus, and biceps muscles.2,11 The history, examination, and laboratory findings of our patient were concordant with idiopathic brachial plexitis. The electromyographic findings further sensitized the localization to posterior cord. There is no special study for the diagnosis of idiopathic brachial plexitis, and the diagnosis depends on exclusion of other causes. Idiopathic brachial plexitis is diagnosed with history and clinical and electromyographic findings. Cervical and brachial plexus MRI, which was performed to exclude cervical radiculopathy and tumor invasion to plexus, was unremarkable in our patient. Although electromyographic findings are sometimes variable, electromyography has been most helpful in localizing the lesions and in confirming the diagnosis.14 MRI scans show high-intensity signals on T2-weighted images in the affected muscles, which are a sign of atrophy.3 MRN is a new method for diagnosing peripheral nerve lesions.8,15-17 MRN was performed in our patient because it has better accuracy when detecting peripheral nerve lesions.18,19 The hyperintense left brachial plexus lesion was definitely compatible with the clinical examination and electromyographic findings in our patient. CONCLUSIONS To our knowledge, this is the first report using MRN to diagnose idiopathic brachial plexitis. MRN did not add to the sensitivity of traditional electrodiagnostics in this case but
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