View source for Craniotomy for extracranial-intracranial revascularization

{{Infobox surgical case reference
| anesthesia_type = General
| airway = ETT
| lines_access = PIV x 2 <br/> Art line <br/> CVC
| monitors = Standard ASA <br/>
5-lead EKG <br/> 
Core temp <br/> 
UOP <br/> 
ABG <br/> 
CVP <br/> 
EEG
| considerations_preoperative = Characterize neurologic deficits <br/>
Consider anxiolytic <br/>
| considerations_intraoperative = Smooth induction <br/>
Maintain CPP <br/>
Maximize flow to ischemic areas <br/>
Decrease CMRO2 <br/>
Decrease intracranial volume <br/>
Smooth extubation
| considerations_postoperative = Careful control of BP <br/>
PONV prophylaxis
| image_file = EC-IC_Bypass_.jpg
}}'''Craniotomy for extracranial-intracranial revascularization''' (also referred to as '''EC-IC bypass''') is a surgical procedure to increase cerebral blood flow.  The procedure involves connecting a branch of the external carotid artery (typically the superficial temporal artery) to a branch of the internal carotid artery (typically the middle cerebral artery).  The anastomosis can be achieved via a vein graft or a direct connection.    

EC-IC bypass is generally indicated for severe stenosis or occlusion of intracranial arteries that is resulting in focal neurological symptoms.  In children, this procedure is used to treat Moya-moya disease.    
== Preoperative management ==
=== Patient evaluation ===
{| class="wikitable"
|+
!System
!Considerations
|-
|Neurologic
|
* Patients typically presenting with focal neurologic symptoms.  Pre-existing deficits should be well characterized and documented. 
|-
|Cardiovascular
|
* Hypertension is a common adaptive response to maintain CPP.  A normal BP may be undesirable in the setting of severe cerebrovascular disease.  
* Patients may have generalized vascular disease, including CAD.   
|-
|Hematologic
|
* Patients often on aspirin through day of surgery
* Anticoagulants impacting PT/PTT typically discontinued 1 week prior to surgery
|}
=== Labs and studies ===

* EKG
* Echo (if concern for cardiovascular disease)
* Coronary angiography (depending on cardiac risk factors)
* Complete blood count
* Chemistry panel
* Coagulation panel
* Cerebral angiography performed to identify cause of neurologic symptoms 

=== Operating room setup ===

* Infusion pumps
* Surface cooling device (i.e. cold-water circulating blanket)
* Warming device 
** Patient will need aggressive rewarming post-anastomosis 
** Consider bladder irrigation, warm-water circulating blanket, forced warm air blanket
* Consider central heat exchanger, especially if patient has high surface-to-volume ratio

=== Patient preparation and premedication ===

* Consider pre-op acetaminophen 1000mg PO 
* Consider pre-op aprepitant if patient has history of severe PONV
* Consider small dose of anxiolytic
* Detailed discussion with patient regarding anesthetic plan 

=== Regional and neuraxial techniques <!-- Describe any potential regional and/or neuraxial techniques which may be used for this case. If none, this section may be removed. --> ===

* Avoid scalp blocks, as they may interfere with donor vessel blood flow

== Intraoperative management ==
=== Monitoring and access <!-- List and/or describe monitors and access typically needed for this case. Please describe rationale for any special monitors or access. --> ===

* Standard ASA monitors
* 5-Lead EKG
* Core temperature
* Urine output
* Arterial blood pressure
* Central venous pressure
* EEG

=== Induction and airway management <!-- Describe the important considerations and general approach to the induction of anesthesia and how the airway is typically managed for this case. --> ===

* Smooth induction is essential
* Goal is to maintain CPP
* Have vasopressors ready to maintain CPP during induction
* Use narcotic to blunt response to laryngoscopy
* Muscle relaxant used to facilitate tracheal intubation 
* 

=== Positioning <!-- Describe any unique positioning considerations, including potential intraoperative position changes. If none, this section may be removed. --> ===

* Supine
* Table typicaly turned 180
* Mayfield skull fixation
* Shoulder roll
* Have all lines directed towards patient's feet, where anesthesiologist typically positioned

=== Maintenance and surgical considerations <!-- Describe the important considerations and general approach to the maintenance of anesthesia, including potential complications. Be sure to include any steps to the surgical procedure that have anesthetic implications. --> ===

* Remifentanil (2-4mcg/kg) to minimize BP elevations during pinning
* Maintenance of anesthesia can be achieved with combination of remifentanil, propofol, and/or volatile agent
* Keep PaCO2 around 40 mmHg
** Hypocarbia may cause unwanted cerebral vasoconstriction in these patients
* Goal net zero fluid balance / Maintain normovolemia
* Dexamethasone may be used to decrease PONV
** Avoid scopolamine for PONV, as it may confound post-op neurologic exams
* Mild hypothermia (33-34°C) can be used to decrease CMRO2 and increase the brain's tolerance to ischemia
* Confirm pre-incision antibiotics
* Avoid long-acting opioids
* Phenylephrine infusion typically used to maintain CPP during procedure
** Phenylephrine typically preferred because it is not arrhythmogenic 
* Continuous neuromuscular blockade typically not needed
* Establish burst suppression (i.e. propofol 1mg/kg) immediately prior to cross clamping of cerebral artery for anastomosis 
** A bolus dose of phenylephrine and/or ephedrine typically needed to counterbalance hypotensive effect of propofol. 
* Aggressive rewarming should start as soon as revascularization is complete
* 

=== Emergence <!-- List and/or describe any important considerations related to the emergence from anesthesia for this case. --> ===

* As anesthetic is titrated down, patient's BP will generally increase
* Beta-blockers (esmolol, labetalol) and vasodilators (clevideipine, SNP) may be needed to maintain tight BP control during emergence 
* Close regulation of blood pressure is essential
* Reverse any residual neuromuscular blockade
* Prophylactic antiemetics should be given before extubation
* Consider IV acetaminophen 
* If patient begins to buck or cough on ETT, extubate or suppress cough reflex (IV lidocaine) 
* Achieve appropriate core body temperature prior to extubation 
* 

== Postoperative management ==
=== Disposition <!-- List and/or describe the postoperative disposition and any special considerations for transport of patients for this case. --> ===

* ICU (typically monitored overnight in ICU)
* Supplemental O2
* Head of bed at 20-30°
* Tight BP monitoring and management post-op (typically maintain at baseline levels)
* Regular neuro checks post-op

=== Pain management <!-- Describe the expected level of postoperative pain and approaches to pain management for this case. --> ===

* Multimodal pain management
* Consider post-op acetaminophen 
* Avoid scalp blocks, as they can interfere with donor vessel blood flow

=== Potential complications <!-- List and/or describe any potential postoperative complications for this case. --> ===

* Seizures
* Stroke
* Hemorrhage at anastomosis
* Brain swelling can be caused by hyperemia in revascularized areas

== References ==
<references />

[[Category:Surgical procedures]]
[[Category:Neurosurgery]]
[[Category:Intracranial neurosurgery]]