Chapter 29 Pathogenesis and Physiology of CNS Disease and Injury

Question 1

Which cell play a key role in cerebral blood flow

Answer 1

Astrocytes match blood flow to neuronal activity

Question 2

What increases CNS perfusion

Answer 2

Hypercapnia
PaO2 <50 mmHg

Question 3

What decreases CNS perfusion

Answer 3

Hypocapnia
Hypotension
Increased intracranial pressure

Question 4

What is normal intracranial pressure

Answer 4

8-15 mmHg

Question 5

Mannitol MOA

Answer 5

Osmotic diuretics increase the osmolality of ECF enhancing flow of water from tissues to interstitial fluid and plasma

Question 6

Mannitol MOA for decreasing ICP

Answer 6

Expands intravascular volume, reducing hematocrit, and blood viscosity, thereby improving CBF and oxygenation

Question 7

Contusion of the brain or spinal cord causes _________ mechanical damage to the CNS and initiates a chain of biochemical events that cause neuronal and glial cell necrosis and apoptosis; this is _______ injury and incites an inflammatory response.

Answer 7

Primary and secondary

Question 8

Primary mechanical damage - Describe

Answer 8

Brain can sustain focal and/or diffuse injury
Focal injury is rare - forces are applied during a period longer than 200ms
Diffuse injury is more commonly associated with trauma or a fall (could also cause both)

Spinal cord can also undergo primary mechanical damage from being compressed or severed

Question 9

Secondary injury mechanism

Answer 9

Ion pumps fail due to injury
Intracellular levels of Na, Cl, and Ca increase causing cytotoxic edema
Decreases astrocytic uptake of glutamate therefore glutamate increases in the extracellular fluid*
Glutamate interacts with NMDA, AMPA, and Kainate receptors causing rapid increase in intracellular Na and slow increase in Ca
Glutamate perpetuates the already high intracellular Na, Cl, and Ca. *

Question 10

What are the components in CSF

Answer 10

Protein - alb
Glucose
WBC
Blood
Water
Na, K, Cl, and Bicarb
Neurotransmitters
pH - 7.3