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Advanced Principles of Anesthesia > Week 1 - Vascular Neurosurgical Disorders > Flashcards

Week 1 - Vascular Neurosurgical Disorders Flashcards

1
Q

What is the incidence of aneurysms?

A

Incidence - 0.3-8%

Unruptured aneurysms: 1-2%/year of rupture

Most aneurysm that rupture are >5mm

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2
Q

What are the three types of aneurysms?

A

Saccular (Berry Aneurysm): located at apex of branch points of major vessels
*85-95% in carotid circulation and 5-15% in vertebro/basilar system

Fusiform: more common in vertebrobasilar system

Mycotic (infectious aneurysm): can be fungal

  • 4% of aneurysms, 3-15% of pts with subacute bacterial endocarditis
  • Distal MCA branches most common
  • 80% mortality if rupture
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3
Q

What are the different size classifications of aneurysm?

A

Small = 0-10mm

Large = 1-2.5cm

Giant = >2.5cm (challenging to treat, direct surgical clipping in only 50%)

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4
Q

Where are the different locations of aneurysms?

A

Internal Carotid Artery: 37%
(25% Posterior communicating artery)

Anterior Cerebral Artery: 35%
(30% Anterior Communicating Artery)

Middle Cerebral Artery: 20%
(13% at bifurcation)

Anterior/Posterior Circulation: 86%/14%

Basilar Artery: 2-10% Terminus, 1% Trunk, 1% PICA

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5
Q

What diagnostic tests are done to diagnose an aneurysm?

A

CT Scan - will detect in >95% of SAH

  • blood appears white in subarachnoid spaces
  • assess for blood in ventricles, infarct, hydrocephalus

MRI - not sensitive within 24-48 hours
-excellent for subacute to remote SAH, >10-20 days

MRA - sensitivity is 86% for determining intracranial aneurysms >3mm in diameter

CT Angiography (CTA) - 95% sensitivity, 80-85% specificity

  • detects aneurysm as small as 2mm in size
  • shows 3D image
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6
Q

What diagnostic test is the gold standard for evaluation/diagnosis of cerebral aneurysms, AVM’s, and arterial dissections?

A

Cerebral Angiogram

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7
Q

What are the surgical treatment options for an aneurysm?

A

Clipping: surgeon places clip directly at neck of aneurysm to exclude it from circulation
-intraop angiogram to confirm complete occlusion of aneurysm

Wrapping: surgeon places material (Muslin wrap) around aneurysm serving as extra protection or stability (not utilized much anymore)

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8
Q

What are preop considerations for cerebrovascular surgery?

A
  • Total procedure time 4-6 hrs
  • Post-clip intraoperative angiography on most cases
  • 2 large IV’s / +/- Central line
  • Normal saline or LR – No Dextrose containing solutions
  • A line for tight BP control
  • Type and cross - 4 units in OR
  • Transport from ICU (Close ventriculostomy for transport – Sedate and paralyze patient to prevent bucking or coughing)
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9
Q

What monitors should be used intraop for cerebrovascular surgery?

A

Standard ASA

Arterial line (pre vs post induction)

Somatosensory Evoked Potentials (SSEP)

EEG

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10
Q

What are induction considerations for cerebrovascular surgery?

A
  • STP or Propofol
  • Remifentanil or Fentanyl
  • Esmolol
  • NMB: roc or cisatricurium (avoid sux if concerned about increased ICP)
  • If increased ICP is of concern, make securing the airway and minimizing hypercapnia a priority
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11
Q

What are anesthetic maintenance phase considerations during cerebrovascular surgery?

A

– O2/Air/Desflurane or Sevoflurane
– Fluids → NS → Albumin (max 20cc/kg)
– Mayfield pin placement → STP (or propofol) + Esmolol
– Non depolarizing neuromuscular antagonist → Ensure profound paralysis throughout procedure. (TOF should never exceed 1/4)
– Remifentanil infusion at 0.1 mcg/kg/min
– Keppra - Administered for postoperative seizure prophylaxis.
– Mild hyperventilation after dural opening to pCO2 28 - 32
– Have Vasoactive drips available (NEO, Sodium Nitroprusside or Nicardipine)

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12
Q

What are emergence considerations during cerebrovascular surgery?

A

– Smooth emergence - avoid coughing or bucking on ETT (Lidocaine 1 mg / kg 30-45 minutes prior to extubation?)
– Ensure patient is awake prior to extubation
– Maintain hemodynamics
– Normocapnia and Normothermia
– Patient may go to ICU intubated - Keep sedated /intubated during transfer

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13
Q

What are endovascular treatment options for aneurysm?

A

Coils: microcatheter used to fill aneurysm sac (GDC, hydrocoil, matrix, etc) – thrombus formation and endothelial cells cover the neck of aneurysm

Stents: used in conjunction with coils to treat broad necked aneurysms

Balloons: balloon occlusion, test balloon occlusion and parent vessel sacrifice, balloon remodeling

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14
Q

What are preop considerations for treatment of an aneurysm?

A
  • Are they symptomatic or asymptomatic?
  • Age - Craniotomy = < 75 years
  • General state of health
  • Presence of comorbidities
  • Functional capacity and lifestyle
  • Psychological state
  • Patient choice of treatment (clip vs coil)
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15
Q

What should be included in a preop evaluation for cerebrovascular procedures?

A
  • Baseline neuro exam and symptoms
  • Review/order appropriate imaging
  • Perform history and physical
  • Preoperative education
  • Routine blood work including CBC w/plt, CMP, PT, PTT, T & S, T & C for OR cases and ??
  • Anesthesia clearance
  • Medical clearance
  • Cardiac Assessment: stress testing, echocardiogram, ekg
  • Pulmonary Assessment: CXR, PFTs
  • Renal Function: creatinine
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16
Q

What are important considerations for cerebrovascular proceudres?

A

Anticoagulation Use (Coumadin): hold 5-7 days for both microsurgery and endovascular surgery – heparin IV or SQ Lovenox if indicated – restart 7 days after craniotomy

Antiplatelet Use (Plavix, ASA): hold 5-7 days prior to craniotomy, start 5 days prior to stent/coil and continue plavix x6 weeks and ASA x 6 months

Platelet Aggregation Testing (Prior to stenting)

Iodine/Contrast Allergy (Premedicate and Hydrate)

Renal Dysfunction (IV hydration before and after)

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17
Q

What are endovascular cerebrovascular procedure anesthetic considerations?

A
  • GETA
  • 2 large PIV’s
  • A line (Best to place A line instead of using surgical sheath)
  • O2/Air/Des or Sevo (Remi not necessary and expensive – Patient can still cough or buck with Remi! – Not a painful procedure)
  • Maintain paralysis - VITAL!
  • Discuss BP management with surgeon
  • Vasoactive drips available (Neo and Nicardipine)
  • Surgeon may request cooling of patient instead of warming
  • Have Mannitol available
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18
Q

What are potential complications with microsurgery (cerebrovascular surgery)?

A
  • Seizures (prophylactic anticonvulsants - keppra)
  • Hemorrhagic Stroke
  • Ischemic Stroke
  • Infection (prophylactic IV ABX)
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19
Q

What are potential complications with endovascular cerebrovascular procedures?

A

Embolic Stroke

Hemorrhagic Stroke

Groin Hematoma/ Pseudoaneurysm/ Infection

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20
Q

What is the role of the subarachnoid space and where is it?

A

Allows for travel of CSF from the SAS to the venous system

Located between the arachnoid and pia mater

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21
Q

What is the definition of a subarachnoid hemorrhage?

A
  • Bleeding into the subarachnoid space
  • Traumatic or Spontaneous
  • Incidence: 10/100,000
  • Aneurysmal Rupture = 75-80% of spontaneous SAH
  • 56% Female
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22
Q

What are the functional outcomes of subarachnoid hemorrhages?

A
  • 10-25 % die before reaching medical care
  • Mortality is 10% within first few days
  • 30 day mortality rate was 46% in one series and over half the patients died within 2 weeks of hemorrhage
  • Overall mortality associated with SAH= 45%
  • 10-30% have moderate to severe disability
  • 66% of patients that have successful clipping of aneurysm never return to same quality of life
  • Patients >70 yrs age fare worse
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23
Q

What are risk factors for subarachnoid hemorrhage?

A
  • HTN
  • Oral contraceptives
  • Cigarette smoking
  • Cocaine abuse
  • Pregnancy and parturition
  • Slight increase risk with advancing age
24
Q

What are the different etiologies of subarachnoid hemorrhage?

A 
Trauma
Aneurysms
AVMs
Cerebral artery dissection
Mycotic aneurysms
Venous thrombosis
Blood dyscrasias

*Unknown etiology in 14-22%

25
Q

What are the signs and symptoms of a subarachnoid hemorrhage?

A
  • Warning headache: 20% HA, N/V, vertigo (small bleed, rapidly expanding aneurysm?)
  • “Worst HA of my life”: Up to 97%
  • Severe HA: 75%
  • Loss of consciousness: 45%
  • Nausea / vomiting: 77%
  • Meningismus: 35 - 75%
  • Third nerve Palsy: 10%
  • Unilateral visual loss/ paraparesis/ photophobia
  • Sudden death: 15 - 35%
26
Q

What are the different clinical grades of a subarachnoid hemorrhage?

A

Grade 0: Unruptured
Grade 1: Minimal HA, slight nuchal rigidity
Grade 2: Moderate-Severe HA, nuchal ridigity, no deficit other than cranial nerve palsy (CN III, VI)
Grade 3: Drowsy, mild focal deficit, lethargy
Grade 4: Stupor, severe focal deficit, early decerebrate rigidity
Grade 5: Deep coma, moribund appearance, decerebrate rigidity

27
Q

What is Fischer grading scale for subarachnoid hemorrhage? (CT Grading)

A

Grade 1: No detectable blood on CT
Grade 2: Diffuse blood, no large clot
Grade 3: Dense blood, >1mm in vertical plane or 5x3 mm in axial plane
Grade 4: Intracerebral or intraventricular hemorrhage

  • Useful as a predictor for cerebral vasospasm
  • Risk of vasospasm = highest in grade 3
28
Q

What are the components to management of a subarachnoid hemorrhage?

A
  • Admission to NICU (neuro checks Q1H)
  • Aggressive blood pressure management prior to endovascular procedure = prevent rebleed (maintain SBP 120-150 by A-line
  • Volume replacement (avoid hypovolemia/ hyponatremia)
  • Prevention of DVT and PE
  • Seizure prophylaxis
  • Monitor for hydrocephalus/ increased ICP
  • Monitor for delayed ischemic neurologic deficit (usually attributed to vasospasm = Nimodipine)
29
Q

How do you treat an aneurysm subarachnoid hemorrhage?

A

Coil vs Clip?

Endovascular Coiling: avoid in wide neck aneurysms, treatment of choice for aneurysms deemed “difficult” to clip

Repeat angiogram in 6 months to 1 year to assure adequate occlusion – may need another embolization due to packing of coils

30
Q

What are side effects associated with subarachnoid hemorrhage?

A
  • Rebleed
  • Intracerebral Hematoma
  • Cerebral edema: due to hydrocephalus, anoxia, apnea, hypo-osmolality
  • Hydrocephalus: 15% on admission (acute), usually associated with poor grade; 10% have chronic HCP
  • Cerebral Infarction: major cause of death, usually due to vasospasm
  • Seizures: 10-26% occurrence at ictus, epilepsy develops in 15%, usually within first 18 months
  • Electrolyte Abnormalities =Hyponatremia
  • Cerebral Vasospasm: usually occurs 4-12 days after SAH, rare in non-aneurysmal settings, can be diffuse or focal usually in region of aneurysm
31
Q

How do you treat cerebral vasospasm?

A

Triple H Therapy: Hypervolemia, Hypertension, Hemodilution

  • Nimodipine - neuroselective calcium channel blocker that is used to prevent / treat vasospasm (given by mouth every 2-4 hours prophylactically
  • Intraarterial Nicardipine - angiogram performed and Nicardipine admin by the surgeon into the cerebral vessels that are in spasm
32
Q

What are Arteriovenous Malformations?

A

Tightly tangled collection of abnormal appearing dilated blood vessels that directly shunt arterial blood into venous system without capillary network

  • Nidus = the focus of the AVM
  • Feeding arteries –> Nidus –> Draining veins

*It is this high flow through fragile vessels which predisposes pts with AVM to have hemorrhage

33
Q

What is the pathology of AVMs?

A
  • Believed to be congenital
  • Mean age at diagnosis is 30yr
  • Usually low flow at birth, childhood and progress to medium to high flow in adulthood
  • Average lifelong risk of bleed is 2-4% per year
34
Q

What are the types of AVMs?

A
  • Can be small (focal) or large involving whole hemisphere
  • Sometimes cone-shaped (base at cerebral cortex, apex points inward)
  • Deep vs Superficial
  • Also can be divided by location (ie. pial, subcortical, paraventricular, etc)
35
Q

What diagnostic tests can be done to diagnose an AVM?

A

CT/CTA - helpful in determining whether AVM has hemorrhaged

MRI/MRA - more helpful to view anatomy, venous draining patterns ect

Cerebral Angiogram Gold Standard - most diagnostic tool for AVM

36
Q

What is the risk an AVM will bleed?

A
  • Lifetime 2-4% per year
  • Each episode of AVM bleed associated with 10% mortality, 20% morbidity
  • If positive history of AVM bleed, risk of rebleed is 6% per year for 1st year then 3% per year
  • Mortality in 2nd bleed is 13%
  • Of all pts with AVMs who have no previous clinical hx of bleed, 25-33% will have radiographic evidence of hemorrhage
37
Q

What are the Spetzler-Martin Grades of AVM?

A

Give “points” based on 3 factors to determine the degree of surgical difficulty

Size:

  • Small (<3cm) = 1 point
  • Medium (3-6cm) = 2 points
  • Large (>6cm) = 3 points

Eloquence of Adjacent Brain: (are you close to important sections)

  • Non-eloquent = 0 points
  • Eloquent = 1 point

Pattern of AVM venous drainage:

  • Superficial = 0 points
  • Deep = 1 point

*Grade 1-2: OR, Grade 3: case by case, Grade 4-5: multidisciplinary approach, Grade 6: “untreatable”

38
Q

What are AVM treatment factors to consider?

A
  • Grade
  • Size/ compactness/ location of AVM and of nidus
  • Neurological status
  • Age of pt
  • PMH, PSH
  • Hx of previous bleed
  • Pt preference
39
Q

What are the different treatment options for AVM?

A

Endovascular Embolization

Surgery

Radiosurgery

40
Q

What are the pros and cons of Endovascular treatment of AVM?

A

Pros: most useful for grade 3, doesn’t require open surgery, faster recovery time
-Onyx glue embolization (done in stages to reduce size)

Cons: embolization alone has cure rate 10%, may require more than one treatment

41
Q

What are the pros and cons of surgical treatment of AVM?

A

Pros: eliminates risk of AVM bleed immediately, reduces seizure risk, usually preferred treatment if pt has had bleed and now has fixed deficit

Cons: invasive, general risk of surgery, cost, degree of difficulty based on AVM grade, larger AMVs are harder to remove

42
Q

What are the pros and cons of radiosurgery treatment of AVM?

A

Pros: outpatient, non-invasive, gradual reduction of AVM flow, no recovery, consider if pt is high OR/anesthesia risk or lesion is hard to get to

Cons: 1-3 years to work, still risk of bleeding in that time, limited in what can be treated

  • has cure rate up to 80% if AVM is <2.5cm
  • 50% cure rate if 2.5-3cm
43
Q

What post-op issues can occur with endovascular embolization and/or surgery of AVM?

A
  • Groin site care/ Incision care
  • Hemodynamics, BP monitoring and control
  • Neuro assessment
  • Headache management
  • Seizure prevention
44
Q

What are the classifications of spinal AVMs?

A

Based on Location:

  • Extradural-Intradural
  • Intramedullary
  • Conus
45
Q

Describe spinal AVM

A
  • Can be insidious, subacute, or acute onset
  • Symptoms relate to onset, location, and type.
  • Likely congenital, error due to abnormality in vascular embryogenesis early in gestation
  • Occurs anywhere along spine
  • Onset of sx usually childhood-young adult
  • Male/Female = occurrence
46
Q

What are the acute symptoms of a spinal AVM?

A
  • Usually related to hemorrhage
  • Acute back pain
  • Acute radicular pain
  • Suboccipital pain
  • Meningismus
  • Sudden loss of consciousness (especially in CSAVMs)
47
Q

What are gradual symptoms of a spinal AVM?

A

Thought to be related to venous steal

Gradual neurological deterioration

Cauda equina syndrome (conus AVMs)

*Listen for spinal bruit

48
Q

How are spinal AVM diagnosed?

A

Spinal Angiography = Gold Standard

-MRI is helpful

49
Q

What are the treatment options for spinal AVM?

A

Goal is to obliterate AVM and maintain SC vascular supply

  • Embolization
  • Surgery
  • Corticosteroids to reduce SC swelling
50
Q

What are anesthetic considerations for spinal AVMs?

A 
GETA
2 PIVs
\+/- A line
Similar OR management as spine cases
Endovascular management is similar to aneurysm treatment
51
Q

What is a Cavernous Malformation?

A

Lesion composed of sinusoidal-like vessels – not separated by normal brain tissue

  • low flow lesion
  • low risk of hemorrhage (very low morbidity/mortality associated w/ hemorrhage)
  • generally not treated unless symptomatic (seizures, tinnitus, headache, III nerve palsy, etc)
52
Q

What is a Moya Moya?

A

A rare, progressive disease of the distal internal carotid arteries and their major branches that is characterized by occlusion of these vessels

-a collateral network of blood vessels at the base of the brain with an unusual angiographic appearance “puff of smoke”

  • more common in Asian population – incidence <1 in 100,000
  • natural history extremely poor if not treated
53
Q

What does pediatric and adult presentation look like in Moya Moya?

A

Pediatric: stroke, TIAs which may alternate sides, cognitive slowing, seizures

Adult: hemorrhage > ischemic symptoms

*More prevalent diagnosis in 1st decade of life and 4th decade of life

54
Q

What are the treatment options for Moya Moya?

A

Superficial Temporal Artery-Middle Cerebral Artery Bypass (STA-MCA Bypass)

Encephaloduroarteriosynangiosis (EDAS)

55
Q

Which is a concern when using a volatile agent for a patient with cerebral ischemia?

A

Shunting of blood to well perfused areas of the brain from ischemic areas

Advanced Principles of Anesthesia (31 decks)

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