M2 Traumatic Brain Injuries

Causes of traumatic brain injuries (TBIs)

fractures of the skull, bleeding, swelling, or an actual tissue injury

• Accidental sport injuries, with or without the influence of alcohol, motor vehicle accidents, and falls are the primary causative factors, although falling objects or direct blows to the head are sometimes involve

Concussion

• Concussion is a mild traumatic brain injury (MTBI).

• It is due to a mild blow to the head causing sudden, excessive movement of the brain.

• Results are reversible.

• Recurrent concussions may lead to permanent damage.

• People at risk may need to re-evaluate their activities to prevent additional damage

Contusion

• Contusion is due to blunt force blow to the head.

• Damage is dependent upon the force of the blow and the amount of tissue injury.

Closed head injury

• Closed head injury occurs when skull is not fractured by the injury.

• However, blood vessels are ruptured and the brain itself is injured.

• Injury increases if the head is forcefully rotated.

Open head injury

• Skull is fractured and bone or other projectiles enter the brain tissue.

  • Compound: Fracture exposes the brain to the environment, severe damage to brain tissue, and high risk of infection.

  • Depressed: Fracture displaces bone below the level of the skull and places pressure on brain tissue.

  • Basilar: Fracture at the base of the skull leads to leaking of cerebral spinal fluid from nose and ears and is often the result of the head hitting the windshield in an auto accident.

• It is predisposed to infection.

Contrecoup 

• Contrecoup is an injury to the opposite side of the brain from the actual impact.

• Damage is due to the brain bouncing off the opposite side of the skull.

• It is seen commonly in acceleration and deceleration injuries.

• It typically leads to minor damage

Primary brain injuries

Causes

Direct injury to the brain

• Laceration

• Crushing injury

• Piece of skull penetrating the brain

• Force causing the brain to shift within the skull

Effects

• Rupture/compression of vessels leads to loss of function in body part controlled by damaged area

• Crushes neurons/glial cells/vessels lead to inflammation, vasospasm, and increased intracranial pressure

• Damaged area dies (necrosis) and scar tissue replaces it

Secondary brain injuries

Causes

Development of post primary injury issues

• Cerebral edema

• Hemorrhage

• Hematoma (collection of blood that develops after vessels rupture—may develop immediately, over time, or postoperatively)

• Vasospasm

• Infection

• Ischemia

Effects

• Increased intracranial pressure

• Loss of blood/oxygen supply to the brain

Epidural Hematoma

• It is a bleed between the dura and the skull.

• It is caused by tear to the middle meningeal artery in the temporal area of the brain.

• Signs occur quickly, with decreasing responsiveness, moving to unconsciousness. (The rapid progression is due to this being an arterial bleed.)

Subdural Hematoma

• It is a bleed between the dura and the arachnoid mater.

• It is caused by a small tear in a vein.

• There is a slow accumulation of blood (slow because this is a venous bleed and therefore low pressure).

• Acute: Symptoms occur within 24 hours.

• Sub acute: Increase in intracranial pressure occurs over approximately one week.

• Chronic: This occurs in older adults because the atrophy of the brain allows for more space for the hematoma to develop.

• Tear in the arachnoid mater space may allow cerebral spinal fluid to escape into the subdural space, further increasing intracranial pressure.

Subarachnoid Mater Hematoma

• It is a bleed between the arachnoid mater and the pia mater.

• It is typically related to traumatic bleeding from the base of the brain.

• Blood mixes with cerebral spinal fluid, prohibiting the formation of a hematoma.

Effects of Hematomas

• intercranial pressure increases

• blood clot beings to form

• blood cells begin to hemolyze and create osmotic pressure, pulling more fluid into the tissue

• size and pressure of clot mass increases leading to more intercranial pressure that can cause the brain to herniate (move out of its current position)

• vasospasm (cerebral vasoconstriction) may also occur leading to additional ischemia and increased damage

Seizures

may be focal or generalized

• caused by accumulation of blood in the brain

Cranial nerve impairment and/or bruising of tissue surrounding the eyes

caused by basilar fractures

Otorrhea (leaking of cerebral spinal fluid from the ear) or rhinorrhea (leaking of cerebral spinal fluid from the nose)

caused by fractures and tearing of the meninges

Otorrhagia (blood leaking from the ear)

caused by fracture with torn vessels and meninges

Fever

caused by hypothalamus impairment or infection (cranial or systemic)

Stress ulcers

caused by increase an in gastric secretions