Awake Craniotomy Protocol
Preoperative Preparation:
Pepcid 20 mg. IV and Sodium Citrate 30 cc PO
Levetiracetam 500 mg IV once patient is in the OR for seizure prophylaxis
Acetaminophen 1 GM IV before incision
Program infusion pumps for Dexmedetomidine .7 Mics/kg/hr, Remifentanil .05 mics/kg/min, propofol 25 mics/kg/min. Start 2 infusions once monitors in place. (DEX/Remi or Prop/Remi)
Dexamethasone 4 mg IV if patient is currently on drug, 10 mg IV if naïve. Dilute in 10cc of NS to give slowly over 10 -15 min.
O2 by nasal cannula 4-6 LPM. Secure NC with cheek Tegaderms.
OR table will be turned 90 degrees with operative site away from anesthesia.
Place radial arterial line on arm closest to anesthesia using 2-5 ccs of 2% Lidocaine injected around artery. Prep in usual fashion and use ultrasound for location.
Start a second IV using local anesthetic as well.
OR nurse will place a Foley catheter using local anesthetic gel.
Mayfield placement
Once lines are secured patient will turn to lateral position with sled support in front and back. Axilla will be placed over edge of bed once head piece is removed. An additional down arm board will be fixed to the head of the bed prior to securing the Mayfield on to the bed.
Surgeons will inject local anesthetic in 3 places: 1 in forehead and 2 occipital area.
Have a bolus of Propofol ready for pinning if indicated. ( 23-30 mg) Personally I rarely have to use.
Once Mayfield frame is secured to OR bed, check for patient neck positioning. Need to have some neck extension with trachea as midline as possible and ample room for patient to open mouth in case GA with LMA is necessary during procedure.
Surgery Start
After positioning, prep and draping will take place. There will be a drape bar placed over patients head to secure sterile towels and allow open access to patient’s face/airway. Secure drapes in such a way where entire side of patient is viewable/accessible. This is necessary for intra-op testing.
Additional local anesthetic will be injected by the surgeon around incision site.
Warn patient about drill noise as this is a loud vibration close to the ear.
IV sedation can be adjusted according to level of patient comfort. Always be vigilant to patient’s loss of consciousness/apnea.
Once surgery started, sedation can be stopped since it’s a short time until testing occurs.
Most common complication that forces aborted procedure vs induction of GA vs prolonged testing is stimulation induced seizure. This is the reason for anti-seizure prophylaxis preoperatively.
Treat first with iced saline on the brain surface. There will always be iced saline available on the instrument table. This controls 90% of seizures that occur.
Should the seizure be a violent tonic/clonic that risks head coming out of pins 20-30 mg of propofol can be given. Be aware patient may become apneic and require LMA placement. Usually this will stop the seizure but will require time for patient to “wake up” and become responsive again.
Testing is performed by our physical therapists using an iPad for object identification, speech and having patient moving down arm and leg.
Once testing is complete, sedation can be induced once again. If surgery is a re operation, tumor is located in insular/ uncal/temporal lobe, or is of sufficient size requiring deep dissection, GA may need to be induced. It’s best to have that discussion with the neurosurgeon preoperatively so planning can be done.
As a guideline, its best to sedate with one drug but usually two are required. One to address hypnosis and one for analgesia. My personal preference is using propofol/remifentanil for younger fit patients with no neurologic focal signs. For older patient and/or those with neurologic deficits, I use Dexmedetomidine/remifentanil.
Dosage guidelines would be: Propofol 25 mics/kg/min, Remi .05 mics/kg/min and Dex .7 mics/kg/hr. Bispectral monitoring may be utilized with adequate sedation at 75-80.
If GA is necessary, have surgeon stop operating until patient is asleep with airway secured. Pre-oxygenate as you would for any other induction. Give an induction dose of propofol, use a tongue depressor to push patients tongue down to get the LMA into the mouth and advance into position.
Use the largest LMA possible and ventilate the patient. Once ventilation established I keep patient paralyzed during the remainder of surgery so coughing is not a risk. TIVA infusions should be increased to GA levels. GA induction always is safest with 2 providers so call your attending. Don’t try this without help.
Once surgery is complete, wake patient as usual but wait to reverse until Mayfield is released from OR table.
A few pearls: Every case is different, No one recipe works for every patient, Plan ahead for the worst, Always turn sedation down before up, Benzodiazepines rarely aid cooperation and frequently affect testing, Avoid long acting agents and communicate with your neurosurgeon.