PMC9969863_01
Clinical presentation. The patient was asked to lift and abduct the proximal end of the right upper limb, and it was observed that the patient had failed to lift and abduct the proximal end of the right upper limb (A). Visual examination showed a square shoulder deformity (A, green arrow) and mild atrophy of the right pectoralis major (A, blue arrow), right deltoid (A, yellow arrow), right supraspinatus (B, green arrow), right infraspinatus, right teres minor (B, blue arrow), and right latissimus dorsi (B, yellow arrow).
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On admission, a detailed physical examination was performed (Figure 1).
MRI neurography of the brachial plexus. Irregular hyperintense signal abnormalities in the multifocal distribution regions of the brachial plexus (blue arrow) was observed on T2-weighted magnetic resonance imaging (MRI) in patients to support neuralgic amyotrophy is likely related to an autoimmune process.
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T2-weighted, fat-suppressed sequences. The examination revealed irregular hyperintense signal abnormalities in the multifocal distribution regions of the brachial plexus (Figure 2) and signs of muscle denervation (diffuse hyperintense signal abnormalities) were found in the right supraspinatus, right infraspinatus, right teres minor, right deltoid, right pectoralis major, right latissimus dorsi, right biceps brachii, and right triceps brachii muscles (Figure 3).
MRI neuroimaging of the brachial plexus. MRI neuroimaging of the brachial plexus can also observe that mild right muscle atrophy (A, blue circle) and the T2 high-signal area of the affected brachial plexus branches with their innervated muscles including the right supraspinatus, right infraspinatus, right teres minor, right deltoid, right pectoralis major, right latissimus dorsi, right biceps brachii, and right triceps brachii muscles (A and B, blue circle).
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T2-weighted, fat-suppressed sequences. The examination revealed irregular hyperintense signal abnormalities in the multifocal distribution regions of the brachial plexus (Figure 2) and signs of muscle denervation (diffuse hyperintense signal abnormalities) were found in the right supraspinatus, right infraspinatus, right teres minor, right deltoid, right pectoralis major, right latissimus dorsi, right biceps brachii, and right triceps brachii muscles (Figure 3).
Neuro-electrophysiological study. For patients with neuralgic amyotrophy during the acute Brucella infection stage, there is positive sharp waves and fibrillation potential in the muscles innervated by the affected peripheral nerves on electromyography, which suggest numerous denervation signs (Ai-Ii :deltoid, latissimus dorsi, pectoralis major, infraspinatus, biceps brachii, triceps brachii, abductor pollicis brevis, extensor digitorum communis muscle, interosseous muscles, blue arrow) and reduced amplitudes of compound muscle action potentials can be observed in the affected peripheral nerves manifesting multifocal axonal loss from affected peripheral origin except for ulnar nerve (Aii-Iii: axillary nerve, thoracodorsal nerve, lateral thoracic nerve, suprascapular nerve, musculocutaneous nerve, radial nerve, median nerve, radial nerve, ulnar nerve, red arrow).
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Electrophysiological studies (Figure 4) were further carried out to clarify the extent of the patient's peripheral nerve injury, and the motor conduction velocity (MCV) examination showed that the right median nerve action potential (MNAP) was decreased.