Week 1 - Vascular Neurosurgical Disorders Flashcards
What is the incidence of aneurysms?
Incidence - 0.3-8%
Unruptured aneurysms: 1-2%/year of rupture
Most aneurysm that rupture are >5mm
What are the three types of aneurysms?
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
What are the different size classifications of aneurysm?
Small = 0-10mm
Large = 1-2.5cm
Giant = >2.5cm (challenging to treat, direct surgical clipping in only 50%)
Where are the different locations of aneurysms?
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
What diagnostic tests are done to diagnose an aneurysm?
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
What diagnostic test is the gold standard for evaluation/diagnosis of cerebral aneurysms, AVM’s, and arterial dissections?
Cerebral Angiogram
What are the surgical treatment options for an aneurysm?
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)
What are preop considerations for cerebrovascular surgery?
- 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)
What monitors should be used intraop for cerebrovascular surgery?
Standard ASA
Arterial line (pre vs post induction)
Somatosensory Evoked Potentials (SSEP)
EEG
What are induction considerations for cerebrovascular surgery?
- 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
What are anesthetic maintenance phase considerations during cerebrovascular surgery?
– 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)
What are emergence considerations during cerebrovascular surgery?
– 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
What are endovascular treatment options for aneurysm?
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
What are preop considerations for treatment of an aneurysm?
- 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)
What should be included in a preop evaluation for cerebrovascular procedures?
- 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
What are important considerations for cerebrovascular proceudres?
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)
What are endovascular cerebrovascular procedure anesthetic considerations?
- 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
What are potential complications with microsurgery (cerebrovascular surgery)?
- Seizures (prophylactic anticonvulsants - keppra)
- Hemorrhagic Stroke
- Ischemic Stroke
- Infection (prophylactic IV ABX)
What are potential complications with endovascular cerebrovascular procedures?
Embolic Stroke
Hemorrhagic Stroke
Groin Hematoma/ Pseudoaneurysm/ Infection
What is the role of the subarachnoid space and where is it?
Allows for travel of CSF from the SAS to the venous system
Located between the arachnoid and pia mater
What is the definition of a subarachnoid hemorrhage?
- Bleeding into the subarachnoid space
- Traumatic or Spontaneous
- Incidence: 10/100,000
- Aneurysmal Rupture = 75-80% of spontaneous SAH
- 56% Female
What are the functional outcomes of subarachnoid hemorrhages?
- 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
What are risk factors for subarachnoid hemorrhage?
- HTN
- Oral contraceptives
- Cigarette smoking
- Cocaine abuse
- Pregnancy and parturition
- Slight increase risk with advancing age
What are the different etiologies of subarachnoid hemorrhage?
Trauma Aneurysms AVMs Cerebral artery dissection Mycotic aneurysms Venous thrombosis Blood dyscrasias
*Unknown etiology in 14-22%
What are the signs and symptoms of a subarachnoid hemorrhage?
- 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%
What are the different clinical grades of a subarachnoid hemorrhage?
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
What is Fischer grading scale for subarachnoid hemorrhage? (CT Grading)
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
What are the components to management of a subarachnoid hemorrhage?
- 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)
How do you treat an aneurysm subarachnoid hemorrhage?
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
What are side effects associated with subarachnoid hemorrhage?
- 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
How do you treat cerebral vasospasm?
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
What are Arteriovenous Malformations?
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
What is the pathology of AVMs?
- 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
What are the types of AVMs?
- 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)
What diagnostic tests can be done to diagnose an AVM?
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
What is the risk an AVM will bleed?
- 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
What are the Spetzler-Martin Grades of AVM?
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”
What are AVM treatment factors to consider?
- Grade
- Size/ compactness/ location of AVM and of nidus
- Neurological status
- Age of pt
- PMH, PSH
- Hx of previous bleed
- Pt preference
What are the different treatment options for AVM?
Endovascular Embolization
Surgery
Radiosurgery
What are the pros and cons of Endovascular treatment of AVM?
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
What are the pros and cons of surgical treatment of AVM?
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
What are the pros and cons of radiosurgery treatment of AVM?
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
What post-op issues can occur with endovascular embolization and/or surgery of AVM?
- Groin site care/ Incision care
- Hemodynamics, BP monitoring and control
- Neuro assessment
- Headache management
- Seizure prevention
What are the classifications of spinal AVMs?
Based on Location:
- Extradural-Intradural
- Intramedullary
- Conus
Describe spinal AVM
- 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
What are the acute symptoms of a spinal AVM?
- Usually related to hemorrhage
- Acute back pain
- Acute radicular pain
- Suboccipital pain
- Meningismus
- Sudden loss of consciousness (especially in CSAVMs)
What are gradual symptoms of a spinal AVM?
Thought to be related to venous steal
Gradual neurological deterioration
Cauda equina syndrome (conus AVMs)
*Listen for spinal bruit
How are spinal AVM diagnosed?
Spinal Angiography = Gold Standard
-MRI is helpful
What are the treatment options for spinal AVM?
Goal is to obliterate AVM and maintain SC vascular supply
- Embolization
- Surgery
- Corticosteroids to reduce SC swelling
What are anesthetic considerations for spinal AVMs?
GETA 2 PIVs \+/- A line Similar OR management as spine cases Endovascular management is similar to aneurysm treatment
What is a Cavernous Malformation?
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)
What is a Moya Moya?
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
What does pediatric and adult presentation look like in Moya Moya?
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
What are the treatment options for Moya Moya?
Superficial Temporal Artery-Middle Cerebral Artery Bypass (STA-MCA Bypass)
Encephaloduroarteriosynangiosis (EDAS)
Which is a concern when using a volatile agent for a patient with cerebral ischemia?
Shunting of blood to well perfused areas of the brain from ischemic areas
