Intracranial Neurosurgery ppt 2

Question 1

Intracranial aneurysms are defined as:

Answer 1

focal protrusions arising from weakened arterial walls usually at major bifurcations of the arteries at the base of the brain

Question 2

Intracranial aneurysms are most commonly treated by:

Answer 2

endovascular coiling (>50%) or microsurgical clip ligation.

Question 3

Most important surgical considerations for intracranial aneurysms:

Answer 3

clinical presentation, aneurysm size and location, patient age, neurologic status, and medical comorbidities

Question 4

Most common intracranial aneurysm clinical presentation:

Answer 4

Aneurysm rupture

Question 5

System used for prognostic clinical outcome

Answer 5

Hunt Hess grading system (1 asymptomatic, 5 deep coma)

Question 6

anterior intracranial aneurysms position:

Answer 6

supine, mayfield headrest, turned 30-45* to side away from aneurysm

Question 7

posterior intracranial aneurysms position:

Answer 7

supine or lateral with mayfield headrest

Question 8

EBL intracranial aneurysm:

Answer 8

250-1000 ml

Question 9

Intracranial aneurysms considerations:

Answer 9

arterial clipping, mild hypothermia, intro angiography with access to femoral artery, electrophysiologic monitoring, brain relaxation, lumbar subarachnoid CSF drainage, decadron IV

Question 10

intracranial aneurysm prep anesthesia considerations:

Answer 10

• 23% have neurogenic pulmonary edema
• PVCs, T wave inversion and ST depression are common
• Decreased Magnesium
• May present with increased ICP or cerebral vasospasm
• Digital subtraction angiography is gold standard for detection
• Pt should be Euvolemic
• hyponatremia from SIADH
• aline for tight BP control

Question 11

increase in BP in intracranial aneurysm pt preop

Answer 11

rebleed, permanent neurologic deficits, or death

Question 12

substantial decrease in BP in intracranial aneurysm prep:

Answer 12

cerebral ischemia or infarction

Question 13

intracranial aneurysms induction:

Answer 13

• Smooth induction
• Decrease cerebral blood volume by inducing cerebral vasoconstriction
• Pts on nimodine may require pressors ie phenylephrine during and after induction
• Patients may benefit from moderate hyperventilation during induction

Question 14

intracranial aneurysms maintenance:

Answer 14

• Iso or Sevo ½ Mac if EP monitoring
• Avoid N2O
• Propofol gtt: ↓ cerebral blood volume, ↓ cerebral metabolism, and ↓ CMRO2

Question 15

↓ PaCO2 leads to:

Answer 15

↓ cerebral vascular volume (better surgical access) + ↑ CBF to ischemic areas (“Robin Hood” effect) + ↓ anesthetic requirements + ↑ lactic acid buffering.

Question 16

Mannitol/furosemide leads to:

Answer 16

↓ K+; monitor level and replace as necessary.

Question 17

If mannitol is administered too rapidly, what could occur?

Answer 17

↓ BP may occur, 2° peripheral vasodilation.

Question 18

Mild hypothermia (33–34°C) is used to:

Answer 18

to ↓ CMRO2and to ↓ susceptibility to ischemic injury during temporary clip application.

Question 19

At 30*C, CMRO2 decreases

Answer 19

~ 30%

Question 20

BP control: During aneurysm exposure

Answer 20

decrease MAP to ~80% baseline

Question 21

BP control: During temporary clipping

Answer 21

increase MAP to ~120% of baseline

Question 22

BP control: postclipping

Answer 22

MAP typically 70-90 mmHg

Question 23

BP control: if aneurysm ruptures

Answer 23

decrease MAP to 40–50 mm Hg

consider carotid compression

Question 24

Deep hypothermia and CPBP is used only with what aneurysms?

Answer 24

> 2.5 cm in diameter

Question 25

intracranial hemorrhage emergence:

Answer 25

Hunt Hess 4 and 5- remain intubated and sedated post-op Hunt Hess 1-3- titrate BB and vasodilators as needed smooth emergence, no cough HOB elevated 30* on transport

Question 26

Intra-op Concerns for AVM

Answer 26

Fiberoptic awake intubation if patient arrives with stereotactic frame. Stereotactic frame is placed in pre-op awake with local anesthesia then patient goes to CT or MRI. VAE Central line Aline Mild hypothermia Brain Relaxation (decrease PaCO2, mannitol/furosemide)

Question 27

Emergence for AVM

Answer 27

Increases in BP treat with B-Blockers or vasodilators Close regulation of BP is key Suppress cough with lidocaine IV HOB elevated 20-30 degrees BP should be maintained 10% below baseline

Question 28

Craniotomy for Tumor Pre-Op Considerations

Answer 28

Neurogenic pulmonary edema | Increase ICP leading to Cushings Triad (HTN, Resp Depression & Bradycardia)

Question 29

Anesthesia for Craniotomy

Answer 29

Stereotactic frame are placed on the patient’s head The patient is taken to CT/MR for determination of the exact tumor site. Surgeons may visualize certain tumors by utilizing iv fluorescent dyes (e.g., fluorescein) When used in conjunction with a specialized operating microscope, these compounds allow greater definition of the tumor and its boundaries with normal brain tissue. Anaphylactic reactions can occur with the use of these agents.

Question 30

Stereotactic Surgery Considerations

Answer 30

Risk of air embolus Brain stem manipulation causes BP and pulse instability Dural patch is used to expand dura at foramen magnum

Question 31

Craniotomy Intraoperative concerns

Answer 31

``` Awake Fiberoptic Intubation if stereotactic frame present Minimize Increases in ICP and MAP Pre-cordial doppler BAER, SSEP, MEP CVP ```

Question 32

Emergence Craniotomy

Answer 32

Increases in BP treat with B-Blockers or vasodilators Close regulation of BP is key Suppress cough with lidocaine IV HOB elevated 20-30 degrees Surgeon may request transient increase in MAP 90-100mmHg to test hemostasis after the tumor is resected

Question 33

Awake Craniotomy

Answer 33

May be used for epilepsy Tumors involving motor or speech Done under MAC or (asleep- awake- asleep) technique LMA or ET

Question 34

Awake Craniotomy- Premapping

Answer 34

``` Mannitol slow IV infusion Midazolam & Dexmedetomidine Propofol gtt Scalp block Aline Foley Mayfield headrest under Local anesthesia ```

Question 35

ventricular shunt- diagnosis:

Answer 35

hydrocephalus

Question 36

2 approaches to ventricular shunt:

Answer 36

Ventriculoperitoneal or Ventriculoatrial

Question 37

Ventricular shunt pre-op:

Answer 37

Cushings triad Headache with ICP > 15mmHg No pre-op med required

Question 38

Ventricular shunt induction:

Answer 38

minimize ICP | maintain normovolemia

Question 39

Ventricular shunt maintenance:

Answer 39

PeCO2 35-40 mmHg Hyperventilation and hypocarbia make cannulation of vessel difficult Maintain normotension: Catheter tunneling is stimulating