The causes of mental retardation need not be present at birth. Mental retardation may be acquired during later development (but prior to eighteen years of age). In this context, physical brain trauma is a possible cause of mental retardation. Brain trauma results from an injury to the brain caused by an outside physical force. The head injury may be an open or closed wound caused by a trauma occurring post-birth, and would not include damage occurring during the birth process, or damage caused by any congenital or degenerative impairments.
Congenital conditions are present before birth, while degenerative impairments are progressive in nature. Progressive brain diseases include but are not limited to Spinal Muscular Atrophy, which is an inherited neurological-muscular disorder and Batten Disease, which is an inherited metabolic disease that leads to the progressive decline of brain functioning.
Physical brain trauma may be caused by abuse or by any injury to an infant or child's head. In some cases, the baby is dropped or thrown. Shaken baby syndrome is a tragic condition resulting from damage caused when a caregiver shakes an infant. In this case, the child's brain makes contact with the skull while it is shaken, resulting in bruising, nerve damage, and swelling.
