The onset of rotator cuff impingement symptoms in most cases is associated with a single episode of overuse. In most patients, this episode event occurred at some previous time, and that shoulder joint has never returned to normal since. However, the primary event leading to rotator cuff impingement syndrome is often relatively minor and not remembered. The most distinctive feature of rotator cuff impingement syndrome is shoulder pain: 1. Early on, the pain is sharp and intermittent. 2. As the impingement progresses, the pain becomes more constant and prolonged. 3. Shoulder pain is usually present after the onset of impingement. 4. Once the inflammation starts, simple movements can cause pain, and over-the-top movements aggravate the pain. When the arm is in this position, there is less room for the subacromial bursa to move, increasing the pressure on the bursa. 5. It does not hurt to move the arm at waist level because there is more room for the bursa to move and the pressure is reduced. Pain is usually aggravated at night for two reasons: inflammation and swelling of the shoulder increase after use during the day, thus increasing pain at night; brain activity decreases at night; and attention is more easily focused on the pain. After a careful history and physical examination, the doctor will perform certain muscle tests to clarify if there is a rotator cuff tendon tear and to rule out other conditions. The doctor may position the arm in a specific position to replicate the symptoms described to clarify the diagnosis. Rotator cuff impingement and tears are easy to diagnose for an orthopedic surgeon experienced in the shoulder joint. Further testing and evaluation includes: 1. Diagnostic injections for closure can help your doctor differentiate between rotator cuff impingement syndrome (or subacromial impingement syndrome) and a full rotator cuff tear. A local anesthetic is injected into the subacromial bursa with inflammation to eliminate pain. If the pain is blocked and the shoulder strength returns, then the weakness is due to pain and the rotator cuff tendon is not torn. 2. X-rays can reflect signs of arthritis, fractures, and bone spurs on the acromion. Because X-rays only show bony structures and not soft tissues, there are often no positive findings in the early stages of rotator cuff injury. MRI (magnetic resonance imaging) can show muscles and other soft tissues that are not visible on X-rays. 4, Shoulder arthrography is another method that can help diagnose rotator cuff tears. 5. Ultrasound can also be used to diagnose rotator cuff tears, but the results are difficult to assess and are very dependent on the skill of the operator and the physician making the diagnosis.