Laryngospasm is an uncontrolled or involuntary muscular contraction (spasm) of the vocal folds. The condition typically lasts less than 60 seconds, but in some cases can last 20–30 minutes and causes a partial blocking of breathing in, while breathing out remains easier. It may be triggered when the vocal cords or the area of the trachea below the vocal folds detects the entry of water, mucus, blood, or other substance. It is characterized by stridor and/or retractions. Some people suffer from frequent laryngospasms, whether awake or asleep. In an ear, nose, and throat practice, it is typically seen in people who have silent reflux disease. It is also a well known, infrequent, but serious perioperative complication.