Traumatic Brain Injury Flashcards
Defining features of concussion
- closed-headed TBI following an impact
- loss of consciousness
- typically, transient, anterograde amnesia, period surrounding time of impact
Distribution of concussion
- focal
- diffuse or non-localizing signs: confusion, disorientation, dizziness, HA
Mental status and supratentorial signs of concussion
- disruption of executive functions: concentration, attention, working memory
- language deficits
- behavioral changes from baseline
- olfactory deficits, VF deficits
Cranial nerves and concussion
- pupils: symmetrical? Reactive to light?
- oculomotor deficits, especially UMN signs; gaze deviation/palsy
Mobile patient eval for concussion
Lots of low tech tests and new apps for mental status
Histopathology and neuroimaging of concussion
- single concussion typically do not produce a lesion
- structural neuroimaging may be normal
- swelling can occur, which is visible as change in signal intensity in CT and MRI
Pathophysiology of concussion
- Focal or diffuse depression in neural activity
- reduced cortical activity. Acute suppression of neural activity may be followed by an increase in neuronal excitability and potential vulnerability to excitotoxicity if another impact occurs
Metabolic impairment of concussion
- reduced glucose utilization
- reduced mitochondrial function
Various other physiological changes of debatable significance or consistency in concussion
- cortisol hyper secretion
- gene expression changes
- changes in extracellular environment-edema related ion gradient change
Course of concussion
- single concussive event or mild TBU typically produce no permanent lesion
- functional recovery is typically complete
Pathophysiological changes and recovery in concussion
Unclear if pathophysiological changes have fully reversed at point when functional recovery is back to baseline performance
Current consensus on recovery time for concussion
Do not return to risk related activities for at least 7 days
Current consensus on risk of multiple injuries
2nd concussion less than 7 days after 1st concussion will probably result in permanent damage and permanent deficits
Repeated concussion, especially the inner-impact interval is <7 days, can lead to neurodenegnerative process
Chronic traumatic encephalopathy (CTE)
Histological features of chronic traumatic encephalopathy (CTE)
- hyper-phosphrylated tau, microtubule degeneration, axonal degradation
- neurofibrillary tangles
- diffuse distribution, but may heavily affect prefrontal and temporal lobes
Distribution of CTE
Initially focal (peri-vascular) but becoems diffuse
Temporal profile of CTE
Insidious, probably progressive
Cognitive changes in CTE
Impaired concentration, executive function, working memory, learning difficulty
Behavioral and emotional changes in CTE
Personality changes, co-morbid depression, irritability, volatile emotional expression
What is CTE similar to
Alzheimers
What is the difference in distribution of Alzheimer’s and CTE
Alzheimers starts in the hippocampus and goes to temporal lobe
CTE heavily affected in the prefrontal and temporal lobes
What’s the difference in cognitive changes between CTE and alzheimers
CTE has very diffuse and large variety of problems
Alzheimers is specific memory loss
What are the dark spots that you can see on brain tissue of CTE?
Neurofibrillary tangles
What is the primary determinant in the severity of conscussion
Onset of loss of consciousness
Loss of consciousness <1 hour ago
Mild
Loss of consciousness 1-24 hours ago
Moderate
Loss of consciousness >24 hours ago
Severe
Glasgow coma scale: 13-15
Mild
Glasgow coma scale: 9-12
Moderate
Glasgow coma scale of <8
Severe
Anterograde amnesia in mild TBI
<24 hours
Anterograde amnesia in moderate TBI
> 24 hours
Anterograde amnesia in severe TBI
> 7 days
What’s the difference between a concussion and a contusion?
Contusion actually has a lesion.
-lesion and clearance/isolation of debris by glia
Where is there potentially bleeding in a contusion
- epidural
- subdural
- subarachnoid
- intra-parenchymal
Things to watch for in contusion
Mass effects, especially herniations
-brain can become bruised by contacting rough bony surfaces too
Burst lobe contusion
Temporal lobe may be removed neurosurgical yo preserve rest of brain
Coup, contra-coup concept of injury TBI
Being hit on frontal part of head and getting damage to both the frontal lobe and occipital lobe
-shockwave effect that can lead to more than one lesion site
Which do you see diffuse axonal injury in, alzheimers or concussion/contusion
Concussion/contusion
Scenarios that would give you diffuse axonal injury
- repeated linear impact concussion
- single cortical contusion event
- rotational (angular acceleration) brain injury
Pathophysiology of diffuse axonal injury
- structures being compressed by de-acceleration on impact
- white matter tracts getting stretched by shearing forces
- if severe, axons can be severed
Neuroimaging and histology of diffuse axonal injury
- spots of hypointensities or absence of signal in neuroimaging of white matter
- axons show swollen varicosities (bead like terminals)
- some axons degenerate, leaving debris from varicosities
What part of the brain is important to look at on a scan to check for diffuse axonal injury
Centrum ovale
Rotational or angular acceleration injury
- component of common scenarios of impact injuries of the brain (vehicle accidents)
- rotation of head causes contusions against calvarium or skull base features
- stretching and shearing forces cause diffuse axonal injury
Blast-induced brain injury
- proximity to explosion involves exposure to shockwave
- compresses body and skull enough to produce mild TBI
- diffuse axonal injury may be the main problem, but new avenue of research
