People usually first notice accessory nerve disease when one shoulder starts to droop and everyday tasks like lifting the arm above the head, brushing hair, or carrying a bag feel weak or awkward. Some feel aching or burning along the neck and shoulder, and others spot the shoulder blade sticking out a bit when pushing against a wall; doctors often confirm it by seeing limited shoulder elevation and weakness in the trapezius muscle. These first signs of accessory nerve disease often appear after neck surgery, a biopsy in the upper neck, or a traumatic injury, but they can also develop without a clear trigger.