Craniocerebral injury is a common condition, second only to limb injuries, and is primarily caused by traffic accidents, falls from heights, slips, and firearms. The mortality and disability rates of craniocerebral injuries rank the highest among injuries to all parts of the body.
Mechanisms of Craniocerebral Injury
Injuries caused by the direct application of force to the head are referred to as direct injuries, while injuries caused by force applied to other parts of the body and transmitted to the head are referred to as indirect injuries.
Direct Injuries
Acceleration Injuries
Injuries occur when a relatively stationary head is suddenly struck by external force, resulting in head acceleration in the direction of the applied force. Examples include blunt force trauma. The primary site of injury is at the point of impact, known as a coup injury.
Deceleration Injuries
Injuries occur when a moving head suddenly collides with a stationary object, halting its motion. Examples include falls when the head is stopped by an object. This type of injury affects both the point of impact and the brain tissue at the site opposite to the impact, known as a contrecoup injury.
Compression Injuries
Injuries occur when two or more forces from different directions simultaneously act on the head, causing skull deformation. Examples include injuries from compression by vehicle wheels.
Indirect Injuries
Injuries occur when a patient lands on the lower limbs or buttocks during a fall. The force transmits through the spine to the skull base, causing skull base fractures and brain injury.
Injuries occur when force is applied to the torso, causing sudden acceleration of the torso. Due to inertia, the head lags behind the torso and is then rapidly whipped forward by the motion of the torso. This causes hyperextension or hyperflexion at the cranio-cervical junction, leading to injuries of the medulla and spinal cord at their connection, known as whiplash injuries.
Injuries occur when the chest is abruptly compressed, causing a sudden rise in thoracic pressure. This leads to retrograde blood flow through the superior vena cava, resulting in diffuse petechial hemorrhages in the skin and mucosa of the upper chest, shoulder, neck, head, and facial regions, as well as in brain tissue. This condition is referred to as traumatic asphyxia.
In clinical practice, craniocerebral injuries may involve multiple distinct mechanisms. For instance, a vehicle collision impacting a patient's torso can induce whiplash injury to the head through rapid acceleration. Subsequently, when the patient falls and strikes their head against the ground or other obstacles, deceleration injury occurs. Further crush injury may result if the head is then compressed by vehicle wheels. Therefore, the injury mechanisms in each patient must be carefully analyzed to make an accurate assessment of craniocerebral injuries.
Classification
In clinical practice, the severity of craniocerebral injury, mechanisms of injury, pathological changes, and variations in the course of the condition are used to determine appropriate treatment measures. A suitable classification system is applied to guide medical practice. Currently, the Glasgow Coma Scale (GCS) is one of the widely used methods internationally. The GCS scoring method was introduced in 1974 by Teasdale and Jennett from the Glasgow Institute of Neurological Sciences. It evaluates patients' motor responses, verbal responses, and eye-opening responses. The total score reflects the degree of consciousness impairment and categorizes post-traumatic coma into three types:
- Mild (13–15 points): Coma duration of less than 20 minutes after injury.
- Moderate (9–12 points): Coma duration between 20 minutes and 6 hours after injury.
- Severe (3–8 points): Coma duration exceeding 6 hours after injury or deterioration of consciousness within 24 hours after injury with coma lasting more than 6 hours.
Table 1 Glasgow coma scale (GCS)
The maximum score of 15 indicates full consciousness, while the minimum score of 3 indicates deep coma.
To be continued