Traumatic Brain Injury l: Introduction

Traumatic brain injury (TBI) is a disruption of normal brain function caused by external mechanical force, such as a direct impact or penetrating head injury. TBI is a heterogeneous condition, meaning its effects vary based on injury type, location, and severity. It can affect both brain structure and function, producing a wide range of clinical outcomes.

TBI severity is classified using the Glasgow Coma Scale (GCS), which evaluates eye opening, verbal response, and motor response. Two additional clinical measures—loss of consciousness (LOC) and post-traumatic amnesia (PTA)—help assess brain dysfunction. LOC measures unresponsiveness duration, while PTA reflects the period when new memories cannot form.

Mild TBI, also called concussion, commonly develops after sports-related injuries. It is defined by a Glasgow Coma Scale score of 13 to 15, loss of consciousness lasting up to 30 minutes or absent, and post-traumatic amnesia lasting less than 24 hours. Although classified as mild, symptoms still require careful clinical evaluation.

Moderate TBI may result from motor vehicle crashes and is defined by a Glasgow Coma Scale score of 9 to 12. Loss of consciousness lasts 30 minutes to 24 hours, and post-traumatic amnesia persists for up to 7 days. This level of injury shows more noticeable impairment in brain function compared to mild TBI.

Severe TBI can occur after high-impact events such as major falls and is defined by a Glasgow Coma Scale score of 3 to 8. Loss of consciousness lasts more than 24 hours, and post-traumatic amnesia continues for more than 7 days. This reflects significant disruption of brain activity and carries high risk of long-term neurologic impairment. Severe TBI may lead to increased intracranial pressure and secondary complications.

The Glasgow Coma Scale (GCS) is a bedside tool that evaluates eye opening, verbal response, and motor response to assess consciousness level. The total GCS score helps clinicians classify TBI severity and guide clinical management. Combined with loss of consciousness duration and post-traumatic amnesia, GCS provides comprehensive assessment of brain dysfunction.

Loss of consciousness (LOC) refers to the duration of unresponsiveness immediately following injury, while post-traumatic amnesia (PTA) describes the period when individuals cannot form new memories. Together, these measures provide clearer understanding of brain dysfunction extent. LOC and PTA duration help differentiate mild, moderate, and severe TBI classifications.