Concussion

Clinical syndrome caused by mild degree of head injury, loss of consciousness for a relative brief period of time and amnesia

Closed Head Injury 

dura leaflet covering the brain is intact --> barrier fxn against infection of the underlying CNS. 

Open Head Injury 

Primary Injuries 

Occur at the immediate time of injury 

complications: fractures, hemorrhage, contusions (bruising), lacerations (cuts/tears)

Secondary Injury 

Delayed rxn response to complication of injury, mins. to hrs. after injury:

cerebral edema

hypoxia

infarction

infection

"Raccon Eye" phenomenon 

intracranial blood flows through a fracture of the thin orbital plate at the floor of anterior fossa

Battle's Sign 

Battle's Sign

Coup Contusion 

ipsilateral to the side of impact

Pathognomic: blow to the freely moveable, resting head which is accelerated

Contre Coup Contusion 

contralateral to the site of impact and pathognomic of a fall 

Diffuse Axonal Injury (DAI)

high energy parenchymal damage in the white matter

Contusion Hemorrhage

Contusion Necrosis 

Larger, triangular contusion involving the gyral crown: base beneath the pia and apex pointing towards the white matter

Plaque Jaune

Fracture Contusion

Herniation Contusion

transtentorial and tonsillar herniation occurring millisecs after kinetic energy release

Gliding Contusion 

Massive intracranial rotational forces w/ shearing of vessels in white matter --> hemorrhages in centrum semiovale

What happens when an infant has a closed head injury (blunt force)? 

Lacerations (tears) of the white matter due to high water content of the brain. 

What happens to an 'immoveable, fixed head' during a crush injury? 

It results in fractures w/ lacerations and hemorrhage of the brain. 

In falls from great height does the brain suffer contusions? 

NO, contusions are absent, and the body reaches terminal velocity & the head is no longer accelerated @ the time of impact. 

Diffuse Axonal Injury 

• Tearing and shearing of axon due to head injury w/ massive rotational forces w/ episodes of acceleration and deceleration.
• Axons swell forming round pink structures visible w/ H&E.
• Eventually, axons disappear and the myelin surrounding the damaged axons is lost, reflecting a form of 2nd demyelination.

Epidural Hematoma 

Fracture of temporal bone and laceration of the middle meningeal artery. 

Acute Subdural Hematomas 

(Venous)

Shearing of the large cerebral veins in the vicinity of the sagittal sinus (called Bridging Veins) w/ blood collecting in subdural space. 

Chronic Subdural Hematoma 

When blood in a subdural hematoma forms fibrous membranes: an external layers adjacent to dura (parietal) and another beneath hematoma (visceral), adjacent to underlying brain w/ residual blood btw 2 layers

Subarachnoid Hemorrhage 

Traumatic rupture of the surface vessels of the cerebral parenchyma located in subarachnoid space. 

What is the most common cause of clinical SAH? non-medical cause? 

Ruptured aneurysms/ trauma 

Hematoma

large areas of injury due to massive injury to the CNS

Delayed Post-Traumatic Apoplexy 

Massive parenchymal hematomas that spontaneously develop weeks to months later at a site of prior trauma. 

Post-traumatic dementia 

Form of dementia assoc. w/ neurofibrillary tangles and senile plaques w/ diffuse axonal injury. 

Example: boxers and football players (repeated trauma)

Hematomyelia 

free blood in the central canal