Mediastinal shift

Mediastinal shift is an abnormal movement of the mediastinal structures toward one side of the chest cavity, and it indicates a severe imbalance of pressures inside the chest. Such shifts are generally caused by increased lung volume, decreased lung volume or abnormalities in the pleural space, and masses inside the mediastinum or musculoskeletal abnormalities can also lead to an abnormal mediastinal arrangement. Typically a shift is observed on chest x-ray, and also on computed tomography or magnetic resonance imaging. On a chest x-ray, tracheal deviation, the movement of the trachea away from its midline position, can be used as a sign of a shift, and other structures such as the heart can serve as reference points. It is a finding that points to an underlying pathology rather than a disease in its own right.