We describe a case of a 54-year-old woman reporting weakness of the right upper limb, preceded by a period of severe pain in the right shoulder. Despite several orthopedic consultations and two cycles of physical therapy, the symptoms deteriorated over a period of 6 months, and progressive paresis of the extensor muscles of the upper limb and elbow flexion contracture were observed. On the basis of the clinical presentation and results of medical tests including an electrophysiological study that showed axonal damage to the long thoracic nerve, axillary nerve, and posterior interosseous nerve, neuralgic amyotrophy was diagnosed. A treatment with prednisone was introduced, and the patient's condition significantly improved.