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