The exact cause is unknown and the condition can last from a few months up to three years or more.
The shoulder may or may not be painful, but the most debilitating thing is the lack of movement, which can become extremely severe.
This is a clinical syndrome that occurs when the tendons of the rotator cuff muscles become irritated and inflamed as they pass under the arch of the shoulder. The most common symptoms in impingement syndrome are pain, weakness and loss of movement at the affected shoulder. The pain is often worse with overhead shoulder movement and may occur at night, especially if the patient is lying on the affected shoulder.
The onset of pain may be sudden if due to injury, or slowly progressive if due to a gradual process such as a bone spur. Other symptoms can include a grinding or popping sensation that can be felt when moving the shoulder.
This condition is often confused with a frozen shoulder.
Pain is often aggravated by a long period of overhead activity and may occur in episodes.