A 53-year-old woman presents with a 2-week history of fatigue and weakness in her hips. She has also started developing weakness in her shoulders while trying to brush her hair in the mornings. The patient denies any difficulty chewing, blurry vision, or facial weakness. The patient is otherwise healthy and does not report any family history other than pancreatic cancer in her maternal uncle. Neurologic examination reveals 3/5 strength in the proximal muscles of her upper and lower extremities. The patient’s erythrocyte sedimentation rate (ESR) is elevated at 92 mm/h and the creatine kinase (CK) is moderately elevated. Other laboratory values (including TSH and free T4) are within normal limits.
Which of the following is the most likely diagnosis in this patient?a. Amyotrophic lateral sclerosis (ALS)
Polymyositis. The patient in this question is presenting with signs, symptoms, and laboratory values consistent with a diagnosis of polymyositis, an inflammatory myopathy characterized by proximal muscle weakness. Dysphagia and esophageal dysmotility occur in as many as onethird of patients. It typically occurs between 40 and 50 years of age and women are more commonly affected. The elevation in ESR and CK levels support the diagnosis of an inflammatory myopathy. Polymyositis can be confirmed by electromyography (EMG) and positive muscle biopsy. It is treated with corticosteroids. (A) ALS presents with weakness as well, but it is associated with upper and lower motor neuron deficits. (C) Drug-induced myopathy (commonly caused by alcohol, antipsychotic medications, and statins) would present clinically with similar symptoms, but would not have an elevated ESR and CK. (D) Fibromyalgia typically presents with pain, not objective weakness, and would have normal ESR and CK levels.