Traumatic Brain Injuries can be subdivided into 2 broad groups:
1. Closed- Head Injuries (CHIs)
2. Open-Head Injuries (penetrating)
1. Closed- Head Injury (CHI)
- there is no penetration to the brain and the skull
- caused by direct or indirect forces to the head generated by rotational and/ or deceleration such as in vehicle-related collisions and/ or falls
- due to their location, the frontal and temporal lobes are prone to the most damage during CHI
- given their importance in speech and language, communication difficulties oftentimes arise following closed head injuries
- additional problems may involve cognition, swallowing, voice, coordination, balance and walking
Closed Head Injuries may result in
- focal lesions and/ or
- diffuse axonal injury (DAI).
- the damage is located in one specific area of the brain and can be localized on neuroimaging
- focal lesions are usually associated with falls/ direct impact to the head
- often occur at the site of impact (known as coup injuries)
- if the injury is associated with acceleration, the motion of the brain may also cause trauma at sites opposite the point of impact, causing a contrecoup lesion
- this often causes rupture (tearing) of veins in the area of trauma
- focal lesions result in symptoms along the lines of those caused by the orbitofrontal syndrome and include disinhibition. impulsiveness, distractibility, hyperactivity and tangential thinking
Diffuse Axonal Injury (DAI)
- when acceleration is followed by rapid deceleration (motor vehicle accidents), the brain is slammed back and forth or from side to side inside the bony skull
- this jarring movement bruises the gelatinous brain tissue, compresses and stretches axons (part of the nerve cell), and tears blood vessels
- due to the widespread stretching of axons, the brain damage is "diffused" vs. "localized" and is not visible on neuroimaging
- the individual may exhibit a "pseudo-depressed" state, which results in symptoms that resemble the dorsolateral syndrome, such as slowness, perseveration, a lack of initiation and a lack of sustained attention along with coma.