Clinical Reasoning: A 32-Year-Old Man With Painless Bilateral Shoulder Girdle Weakness and Atrophy.

We report a case of 32-year-old man with progressive, asymmetric, proximal weakness of both upper limbs for 14 months. On examination, he had gynecomastia and wasting and weakness of his deltoid, supraspinatus, infraspinatus, pectoralis, biceps, and triceps muscles, along with sensory loss of his left C5-C8 dermatomes. Deep tendon reflexes were depressed in the upper limbs and normal in the lower limbs. There was a history of a road traffic accident 2 years ago without any neurologic deficits. We discuss the clinical approach, differential diagnosis, investigations, and treatment options for bibrachial weakness.