Pathophysiology of Nervous System Trauma Flashcards
What is the definition of traumatic brain injury?
Any form of external injury that affects the normal function of the brain, either transiently or permanently
Who are the most vulnerable populations for TBI and what is the most common cause of non-fatal TBI?
Children and adolescents whose cranial cavities are not fully formed, also adults >75
Leading cause of TBIs is falls
What is the most important outcome of TBI and what patient factors influence recovery?
Disability
Patient pre-injury functioning, socioeconomic status, and access to rehabilitation services have a large effect on recovery
What are the two classifications of TBI related to timing of trauma?
Primary injury - damage caused by mechanical force, occurring at the moment of injury
Secondary injury - damage not caused directly by primary event, but superimposed on brain already affected by primary injury (i.e. bruising, swelling, herniation, all sequellae)
What are some examples of focal vs diffuse injury in TBI?
Focal - scalp injury, skull fracture, or surface contusions
Diffuse injury - diffuse axonal injury, hypoxic-ischemic injury, meningitis, or vascular injury
What is the rating scale of the Glasgow Coma Scale (GCS) and what corresponds to mild, moderate, and severe TBI?
3-15
Mild: 13-15
Moderate: 9-12
Severe: 3-8 (<=8 is comatose)
What are the three categories of evaluation for GCS?
- Eye opening
- Verbal response
- Motor response
What is the scoring scheme for eye opening on GCS?
1 - no opening
2 - opens to pain only (i.e. on forehead)
3 - opens to verbal request
4 - Spontaneously open
What is the scoring scheme for verbal response in GCS?
1 - no response 2 - random sounds 3 - random nonsensical word strings 4 - confused response (not oriented) 5 - oriented to time, place, and person
What is the scoring scheme for motor response in the GCS?
1 - no response
2 - decerebrate - abnormal extension in response to pain
3 - decorticate - abnormal flexion in response to pain
4 - flexion withdrawal of limb from painful stimulus
5 - touch area of painful stimulus (localizes)
6 - obeys commands
-> most objective scale
What is a closed / blunt head injury? What typically causes them?
TBI where skull remains intact. Commonly accidents, falls, acts of violence, sports injuries.
Also, blast-related closed head injuries -> changes in atmospheric pressure, objects dislodged from blasts, or people being thrown into motion by blast
What is a concussion? What are the possible sequellae?
A type of closed head injury where there is instant onset transient neurological dysfunction, with or without loss of consciousness
Possible sequellae include post-concussive syndrome. Repetitive concussions may cause chronic traumatic encephalopathy
What is post-concussive syndrome?
Prolonged symptoms of concussion lasting longer than usual 7-10 days.
Clinical features: headache, dizziness, nausea, memory disturbance, depression, sleep problems, difficulty concentration, mental fog
What is chronic traumatic encephalopathy (CTE)?
Progressive degenerative disease of the brain found in people with severe or repeated blows to the head. Commonly occurs in boxers and football players.
What are common pathological findings of CTE?
Neurofibrillary tangles of tau, and amyloid plaques, accompanied by cerebral atrophy, enlarged ventricles (ex vacuo hydrocephalus), and reduced pigmentation of substantia nigra + locus coeruleus.
Where do contusions occur in terms of dural space and which areas of the brain are most susceptible?
These are bruises / bleeds in the brain parenchyma, caused by rapid brain displacement and disruption of vascular channels -> hemorrhage. Hemorrhage can extend into subarachnoid space as well.
Crests of gyri are most susceptible, where direct force is the greatest. These are most commonly damaged over rough surfaces (i.e. frontal lobes over orbital ridges)
What are blossoming contusions?
Hemorrhagic progression of a contusion ->
Contusions with hemorrhage which expand overtime
or
NEW, non-contiguous contusions
What is diffusion axonal injury (DAI) caused by and what will happen to axons?
Rotational / acceleration injuries with whiplash - axons get torn at nodes of Ranvier due to shearing forces.
There will be perivascular microhemorrhages and formation of swollen axons which accumulate beta-amyloid.
What will happen to patients in severe DAI, and what areas of the brain are most susceptible?
There are unconscious from the moment of injury
-> may remain comatose, vegetative, or severely disabled for life
Areas most susceptible are areas of white matter with long tracts: corpus callosum, midbrain, and deep cerebral white matter
What is the definition of an open / penetrating head injury?
A head injury in which the dura mater is breached -> usually due to high velocity projectiles or bone fragments from a skull fracture.
Define the following skull fracture types:
- Linear
- Basal
- Depressed
- Diastatic
- Comminuted
- Linear - fracture lines radiate from site of impact
- Basal - fracture of basal skull
- Depressed - Skull is depressed into cranial cavity, like a pingpong ball (often in children)
- Diastatic - Separation along suture lines
- Comminuted - fragmented bone into pieces
What is the definition of a displaced skull fracture?
A fracture in which the bone is displaced into the cranial cavity greater than the thickness of the bone
What clinical signs and symptoms are associated with basilar skull fracture?
Raccoon eyes - orbital hematomas
Battle’s sign - bruising near mastoid process
Lower cranial nerve involvement
What is the definition of a compound skull fracture?
Fracture of skull association with laceration of overlying scalp
