PSYCH 261 - Lecture 12 (Brain injury) - uncompleted

Cerebrovascular accident (stroke)

• The disruption of normal blood delivery to brain tissues

Cerebrovascular accident (stroke) - 2 tyes

1. Ischemic stroke

2. Hemorrhagic stroke

Ischemic stroke

• When arteries or capillaries are blocked by:

  • Floating debris

  • Buildup of material inside the blood vessels

  • Constricted blood vessels

• The blockage prevents nutrients from going to the brain cells, therefore causing the cells to die

• Most common

Hemorrhagic stroke

• Involves the rupture or breakage of blood vessels in the brain, which is caused by traumatic brain injury or high blood pressure

• Hemorhhagic stroke can lead to death but that depends on the amount of blood lost during the stroke

Excitotoxicity

Another factor as to why cells die:

• Because the cells overactivate themselves and other neurons, leading to cell death

• Occurs during a ischemic stroke

1. During a stroke, not enough nutrients causes sodium-potassium pump to fail

2. This then leads to an overproduction of glutamate which overstimulates the neurons

3. B/c of the overactivation, it causes an increase in calcium and sodium ions

4. An b/c of the buildup in calcium and sodium ions, it damages mitochondria 

5. Damaged mitochondria releases free radicals that damages tissues

6. And the buildup of cations causes edema (Swelling)

Pump failure → glutamate overload → calcium increase→ mitochondrial damage → swelling and neuron death.

The brain during a hemorrhage stroke

• Causes brain damage through pressure, edema, lack of oxygen, inflammation and toxic chemicals.

1. Leaking blood puts pressures on cell membrane

2. Vasoconstriction causes a decrease in blood which leads to ischemia

3. Cations increases which leads to cytotoxic damage and cytotoxic edema

4. Thrombin is released which triggers blood clotting

5. Thrombin makes NMDA receptors more responsive to glutamate which increases excitotoxicity

6. Iron triggers free radicals

Traumatic brain injury (TBI): Impact deceleration injuries: (1) coup, (2) contrecoup

• Common among people who play spots

• Usually occurs when the head is moving and comes into contact with a object that doesn’t move

• Coup injury: the brain is compressed against the skull at the point of contact with the obstacle

• Contrecoup injury: the brain is compressed against the skull at the point opposite to the point of contact after rebound —> the brain gets hurt on the opposite side of where the head was hit

  • After the head hitting the object, the brain bounces back and hits the back of the skull

Hematoma

• A large bleed creates a large blood mass in the brain which puts pressure on certain brain parts and can then lead to death

Contusion

• A local area of bruising in the brain involving small tears in the blood vessels

Diffuse traumatic brain edema

• Brain swelling

• Causes ventricles to be compressed

• Caused gyri and sulci to not be visible

Symptoms of concussion

1. headaches

2. nausea

3. dizziness

4. memory and attention problems

Chronic traumatic brain injury

causes

1. Alzheimers symtpons

2. Parkinsonian symptons

3. Motor problems

4. mood disturbances

5. impaired cognition