If parents or caregivers cannot find the cause of the inconsolable crying of an infant, they might react sharply and shake the baby, causing brain damage and, as a result, the infant stops crying, explained study leader Concepcion Ruiz Rodriguez of the University of Granada.

Although the seriousness of the brain damage depends on the frequency, intensity and duration of the shake, there are other minor injuries observed due to this syndrome, such as irritability, lethargy, convulsions, vomiting or lack of appetite, and others that are more serious such as eye injury and broken bones.

Most victims are under age 2, and the most vulnerable victims include premature babies, low-weight babies, babies with excessive colic, disabled babies, twins and stepchildren. The aggressors are chiefly men; 44 percent are the father, 20 percent the mother's boyfriend living in the home, 18 percent are babysitters and 7 percent are the mothers, reported the study published in Nursing Journal Rol.