Chronicity is indicated when pain persists for weeks and months. Since patients cannot find relief, especially at night, psychological symptoms soon appear. The pain changes in character and becomes constant. Initially, localized pain at the back of the head and between the shoulder blades progresses to diffuse pain extending across the shoulder and neck region.
The continuous tension of the trapezius, levator scapulae, and rhomboid muscles leads to enthesopathic tendinopathies at the occipital bone, the superior angle of the scapula, and the acromioclavicular joint. Because the shoulder is secondarily involved through the muscles of the proximal limb, pain develops there as part of the chronic process, which may potentially become self-perpetuating.