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AS - N932 Advanced Pathology > Neurological > Flashcards

Flashcards in Neurological Deck (138)
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1

Cellular Processes Activated by Ischemia

1. Cellular acidosis
2. Cellular swelling (cytotoxic edema)
3. Neurotoxicity
4. Enzymatic activation
5. Nitric oxide production
6. Inflammation
7. Apoptosis
8. Necrosis

2

Monroe Kellie

Cranial vault = fixed space
Blood 80%
Blood 12%
CSF 8%

3

CPP

MAP - ICP
Normal 80-100mmHg

4

CBF

CPP/R
Directly proportional to CPP

5

Average CBF

50mL/100g/min
Brain average size 1500g
= 750mL/min
Receives 15% CO

6

Middle Cerebral Artery

Carries 80% blood to the brain

7

Circle of Willis

Provides collateral flow

8

ICP

Normally <10mmHg

9

Cerebral Autoregulation

Myogenic - intrinsic VSMC response in arterioles to MAP changes
Metabolic - CO2 and metabolites vasodilate and directly relax VSMC

10

CSF Production

Adult 21mL/hr or 500mL/day

11

CSF Flow

Produced by choroid plexuses of the lateral ventricles & secreted by the ependymal cells of the choroid plexus
Lateral ventricles via Foramen of Monro → 3rd ventricle via Aqueduct of Sylvius → 4th ventricle → subarachnoid space via Foramen of Magendie → circulates around brain & spinal cord → empty via arachnoid villi (valves)

12

CSF Function

Removes catabolites or toxins
Distributes neurotransmitters to neurons
Brain ISF homeostasis
Development
Nutritive effects
Pressure equilibrium - responds to fluctuations caused by volume changes in 3 compartments w/in rigid skull
Protect CNS from trauma

13

DCML

Dorsal column
Touch
Decussates high

14

Spinothalamic

Anterolateral
Originates in the spine & transmits to thalamus
Pain & temperature
Decussates low
Signal diffuse - difficult to locate

15

Cerebral Edema Types

Increased fluid content = life-threatening condition that develops in response to inflammation reaction
Causes: cerebral trauma, cerebral infarction, hemorrhage, abscess, tumor, allergy, sepsis, hypoxia, & other toxic or metabolic factors
-Cytotoxic
-Vasogenic (damage to endothelial cells impairs BBB)
-Hydrostatic
-Osmotic
-Interstitial

16

Cerebrovascular Accident (CVA)

Ischemic - thrombotic or embolic
Global hypoperfusion - shock or ↑ICP
Hemorrhagic - intracerebral hemorrhage

17

Intracerebral Bleed Associated w/

Hypertension
Anticoagulation therapy or other coagulopathy
Drug & alcohol abuse
Neoplasia (tumors)
Amyloid angiopathy - amyloid (insoluble fibrous protein aggregate) deposits in cerebral vessel walls predisposes to leak (microvascular) bleeding
Infection

18

Aneurysm Rupture Etiologies

Trauma
Inflammation
Atherosclerosis
Congenital

19

Aneurysm Associated w/

Structural abnormalities
Genetics
Atherosclerosis
HTN
Coarctation
Connective tissue disorders

20

Aneurysm Rupture Characteristic Presentation

Sudden onset severe headache
N/V, neck stiffness, photophobia
LOC sometimes
Hypertensive, dysrhythmias, EKG abnormalities

21

Aneurysm Rupture M&M Associated w/

Neurologic ischemia from vasospasm & elevated ICP
Cardiopulmonary arrhythmias, myocardial injury, pulmonary edema
Electrolyte abnormalities hypomagnesemia, - kalemia, -natremia

22

Common Aneurysm Locations

Anterior cerebral artery 40%
Posterior communicating artery 25%
Middle cerebral artery 25%
Only 10% aneurysms develop in the vertebrobasilar system

23

AVM Anesthetic Implications

Intraop bleeding can occur during AVM surgery
Deliberate hypotension to ↓blood loss but consider ischemia and venous thrombosis
Avoid ↑venous pressure

24

Ischemic Stroke

Interrupted cerebral perfusion
1° thrombotic & embolic
Vicious cycle cell hypoxia, edema, & metabolic derangements
3rd leading cause of US death

25

Ischemic Stroke Risk Factors

Increasing age
Underlying atherosclerotic disease
Previous transient ischemic attacks
Associated w/ CV disease (Afib, valve prosthesis, carotid disease, bacterial endocarditis)

26

Ischemic Stroke Anesthetic Implications

Surgery especially CV potential stroke trigger
Patients at risk for stroke - diabetes, HTN, & coagulation therapy
Previous stroke patients - impaired cerebral autoregulation (monitor BP)
Monitor neural function during surgery

27

Venous (Vascular) Air Embolus Risk Factors

Operative site >5cm above R atrium
Numerous large, non-compressed venous channels in the surgical field
Pressure gradient >5cmH2O
Barotrauma to chest causes alveolar rupture into small vein & capillaries
During insertion & removal central venous catheter

28

VAE Clinical Manifestations

Varies according to air nature, volume, & speed entrainment into circulation
Affects CV, respiratory, & CNS
Chest pain, brady or tachy arrythmias, ↑filling pressure, ST segment changes
Dyspnea, tachypnea, "gasp" reflex, hypoxemia, hypercarbia
↓CO → cerebral hypoperfusion; direct paradoxical cerebral embolism via PFO

29

VAE Detection

Consider when unexplained hypotension or sudden ↓ETCO2
SOB after central venous catheter
C/S sudden hypotension & hypoxia after delivery

30

VAE Monitoring Devices

Transesophageal echocardiography most sensitive
ETCO2 most common & easily available