Hypoxic and Ischemic Brain Injury

Question 1

anoxia/hypoxia definition

Answer 1

lack of or insufficient supply of oxygen circulating to tissue in the presence of adequate blood flow

Neurons store virtually no energy, and thus loss of oxygen and glucose results in rapid adenosine triphosphate (ATP) depletion. This leads to neuronal death.

Question 2

Medical Conditions That May Cause Hypoxic-Ischemic Brain Damage

Answer 2

Acute conditions:
* Cardiac Arrest (especially out-of-hospital events)
* Acute respiratory distress syndrome (ARDS) (especially onset out of hospital)
* Carbon monoxide poisoning
* Suffocation, drowning, hanging
* Massive blood loss due to trauma
* Prolonged seizures
* Anesthesia accidents in surgical procedures

Chronic conditions:
* Chronic obstructive pulmonary disease (COPD)
* Obstructive sleep apnea (OSA)
* Asthma

Question 3

Brain regions that show high vulnerability to
hypoxia/ischemia include:

Answer 3

• *watershed cortex/regions (brain regions with high metabolic demands and those at the distal end of cerebral arteries)
• *basal ganglia (striatum, globus pallidus)
• hippocampus (especially pyramidal cells in CA1)
• cerebellar regions (Purkinje cells)
• visual cortex
• thalamus

White matter tracts appear to be generally preserved in hypoxia/ischemia, but they are vulnerable to carbon monoxide poisoning

Question 4

secondary toxic processes triggered by hypoxia/ischemia

Answer 4

Sodium and calcium pumps fail -> excessive levels of glutamate (excitatory) -> excitotoxic to neurons

free radicals are also produced

Question 5

Carbon monoxide (CO) poisoning effects on brain

Answer 5

Carbon monoxide poisoning often results in delayed neurologic deterioration, which may occur 1 to 3 weeks after severe exposure.

Basal ganglia damage is common, contributing to the extrapyramidal features often seen following severe CO poisoning.

Hippocampal atrophy and generalized brain atrophy may be seen months following injury.

Question 6

Carbon monoxide (CO) poisoning neuropsychological deficits

Answer 6

attention
information processing
executive functioning
verbal and nonverbal memory

Question 7

if hypoxia is not severe enough to disrupt ??, CNS damage is unlikely.

Answer 7

consciousness

Mild hypoxia that does not lead to loss of consciousness (for example, high-altitude climbing) may induce mild cognitive and motor impairment that would not be expected to have lasting effects,

Question 8

chronic pulmonary disease that may result in neuropathological changes and cognitive impairment.

Answer 8

Obstructive sleep apnea (OSA)

Chronic obstructive Pulmonary Disease (COPD)

Question 9

Obstructive Sleep Apnea neurocognitive deficits

Answer 9

Severe sleep apnea has been associated with greater risk for white matter hyperintensities and cognitive impairment (learning and recent memory, executive abilities, psychomotor impairments), but results are not consistent across studies.

Question 10

delayed post-hypoxic leukoencephalopathy (DPHL)

Answer 10

most commonly seen following CO poisoning

individual initially makes a good recovery from a neurologically impaired state and may even return home and back to work quickly. There then is abrupt onset of progressive neurologic decline typically involving parkinsonism or akinetic mutism with prominent cognitive impairment.

A majority who survive show significant improvement but are left with lasting neurologic and cognitive impairment.

Imaging studies typically show prominent white matter demyelination particularly in the frontal and parietal regions.

Question 11

Neuropsychological deficits following hypoxic/ischemic injury

Answer 11

memory
attention/processing speed
executive dysfunction (orbitofrontal system dysfunction b/c this is a watershed region)
visuospatial deficits (posterior watershed regions)
overall cognitive decline

hold tests are not typically affected

Question 12

The predominant pattern of brain injury in neonates found to be most strongly associated with long-term outcome, more so than the severity of injury in any given region, is injury to the ???

Answer 12

basal ganglia and thalamus

Question 13

Pediatric Hypoxic and Ischemic Brain Injury

Answer 13

Visuospatial deficits tend to be less severe in children with hypoxic brain injury, whereas intellectual abilities, attention, memory, and behavioral impairments tend to be more pronounced in that population.

The individual with lasting changes in brain functioning may not derive the same maturational benefits from normal childhood and adolescent developmental experiences.

Question 14

Acute respiratory distress syndrome (ARDS)

Answer 14

A severe, often life- threatening medical condition in which the lungs are compromised or damaged and are unable to supply sufficient oxygen to the arterial blood (e.g., hypoxemia).

It can result in anoxic/hypoxic damage to the brain, among many other systemic problems.

Question 15

Apoptosis

Answer 15

In the strictest sense refers to programmed cell death.

Apoptosis is part of normal regulation and turnover of cells, but can also result from pathologic processes such as ischemia.

Question 16

Ischemia vs anoxia/hypoxia

Answer 16

Ischemia results from loss of blood supply perfusion, in contrast to when there is adequate supply but low or lack of oxygen content (anoxia/hypoxia).

In most severe cases, both ischemia and anoxia/hypoxia exist.

Question 17

Secondary hypoxia

Answer 17

Following return of circulation, cerebral blood flow may go through a period of 30–50% reduction, resulting in a mismatch of oxygen requirements and blood flow.

Question 18

Reperfusion Injury

Answer 18

Following reperfusion, several processes ensue that can cause further damage, including free radical formation, nitric oxide toxicity, additional glutamate release, edema and microhemorrhages, and impaired ability to remove toxic metabolites.

Question 19

Compared to adults, children with anoxic brain injury tend to have less severe…

Answer 19

visuospatial deficits

Anoxic brain injury in children tend to result in significantly impaired intellectual abilities, memory impairment, decreased attention span, and behavioral impairments

Question 20

Which cognitive area is least likely to be seen following hypoxic/ischemic damage?

Answer 20

visuospatial deficits. Impaired memory, processing speed, and attention are common cognitive problems following hypoxia/ischemia. Visuospatial deficits are less commonly seen.

Question 21

Children with neonatal hypoxia are at increased risk for:

Answer 21

intellectual disabilities (and to a lesser extent, ASD)