Cranial deformity produced when the bones of the skull fuse too early. Pressure from the growing brain normally causes the skull bones to grow along the seams (cranial sutures) between them. If all the sutures fuse early, the head remains abnormally small, which can cause intellectual disability or blindness. If only one or some fuse early, the skull grows in other directions and becomes deformed. Surgery in the first two years to keep the sutures open longer minimizes these complications.