A TBI is caused by a bump, blow or jolt to the head or a penetrating head injury that disrupts the normal function of the brain. Not all blows or jolts to the head result in a TBI. The severity of a TBI may range from ‘mild,’ i.e., a brief change in mental status or consciousness to ‘severe,’ i.e., an extended period of unconsciousness or amnesia after the injury.
TBI is complex and unpredictable in its outcomes. Serious injury can occur without obvious physical disabilities. Both mild and severe TBI can result in lifelong impairments – requiring long-term care services. In cases of stroke, drowning, or asphyxiation, the brain injury incurred is called an Acquired Brain Injury (ABI) and treatment and services may differ from those described herein.
Source – Michigan Department of Health & Human Services