Definition: GCS 14-15
Neurologic dysfunction that varies without gross lesions (ie patients have trouble with memory, attention, and executive functioning
Occurs after a blunt force or acceleration-deceleration head injury
Likely secondary to metabolic insult ie low oxygen state, ion changes
Structural imaging on MRI or CT might not indicate any injury
Often evidence on microscopic level of injury with histology
Important to not expose the already injured<unk>  to repeated insults which is why there are usually worsening symptoms after a repeat concussion
2.5 million people sustain a TBI in the United States every year
75 to 95 percent, are<unk> 
Most common causes of TBI are motor vehicle accidents (20 to 45 percent), falls (30 to 38 percent), occupational accidents (10 percent), recreational accidents (10 percent), and assaults (5 to 17 percent)
Contusions
Bruises to<unk>  parenchyma
Hematomas
Epidural hematoma
Subdural hematoma
Intraparenchymal
Intraventricular
Subarachnoid hemorrhage
Diffuse axonal injury
Direct cellular damage
Neurons
Axons
Tearing and shearing of tissues
Bruises to<unk>  parenchyma
Epidural hematoma
Subdural hematoma
Intraparenchymal
Intraventricular
Subarachnoid hemorrhage
Neurons
Axons<unk>  swelling causes increased ICP which compresses the tissue causing ischemia with direct compression of the vasculature causing<unk>  tissue herniation and<unk>  death
Leads to expansion of the original injury (predominantly metabolic insult)
Calcium and sodium shifts
Mitochondrial damage
Production of free radicals
Ultimately leads to damage to axonal integrity and axonal transport
Enzyme activity leads to apoptosis
Microscopic structural injury is often unidentifiable on CT or MRI
Calcium and sodium shifts
Mitochondrial damage
Production of free radicals
Enzyme activity leads to apoptosis
vasoconstriction
HTN, Hypocarbia, alkalosis
No good way to measure cerebral blood flow
Use CPP as surrogate
CPP is amount of pressure needed to perfuse the<unk> 
CPP=MAP-ICP
When ICP elevates, CPP decreases
Normal ICP
15 in adults
<10 to 15 in children
1.5 to 6.0 in infants
Autoregulation allows the body to control the cerebral blood flow
Autoregulatory mechanism is damaged in most TBI patients
HTN, Hypocarbia, alkalosis
Use CPP as surrogate
CPP is amount of pressure needed to perfuse the<unk> 
CPP=MAP-ICP
When ICP elevates, CPP decreases
Normal ICP
15 in adults
<10 to 15 in children
1.5 to 6.0 in infants
CPP is amount of pressure needed to perfuse the<unk> 
CPP=MAP-ICP
When ICP elevates, CPP decreases
Normal ICP
15 in adults
<10 to 15 in children
1.5 to 6.0 in infants
When ICP elevates, CPP decreases
Normal ICP
15 in adults
<10 to 15 in children
1.5 to 6.0 in infants
15 in adults
<10 to 15 in children
1.5 to 6.0 in infants
Autoregulatory mechanism is damaged in most TBI patients
Mild traumatic brain injury
Traumatic brain injury
Moderate-to-severe traumatic brain injury
Intracranial hemorrhage
Post-concussive syndrome
Traumatic intracerebral hemorrhage
Elevated intracranial pressure
Ischemic stroke