High and low shoulders are not necessarily scoliosis, but may also be spasm and tension in the trapezius muscle. In most cases, high and low shoulders are caused by scoliosis. Patients may present with scoliosis of the thoracic spine, back pain, back muscle tension, limited movement of the thoracic spine, and bilateral asymmetry of the shoulder joint, giving the appearance of high and low shoulders. In addition, a few cases such as trauma to the trapezius muscle, cervical spondylosis, or a drop pillow can cause tension and spasm of the trapezius muscle. The spasm of the trapezius muscle causes the muscle to shorten and pull on the shoulder joint, causing the shoulder joint on one side to be elevated and forming a high and low shoulder. Therefore, patients with high and low shoulders may not necessarily have scoliosis, but may also be caused by muscle spasm.