Preop

Moya-moya patients are extremely susceptible to intraoperative strokes. The following guidelines are absolute: 

• No mannitol or diuretics
• Maintain normocapnia: PaCO2 40-45
• SBP 140-180

Preinduction a line, know pre induction SBP and keep in that range intra op.

Setup

SSEPs alone for Moya-Moya STA-MCA bypass. If bypass is planned to a more proximal MCA branch (e.g. M2), then motors may be used. 

Positioning

Turn the bed 180. Pull the patient north until the shoulders are at the break in the bed. Place a pink foam bump longitudinally under the shoulder. Place thin purple foams between the arm and torso on both sides then pull the sheet up and wrap the patient with 3-inch tape like a burrito. 

Place the Layla bar holder on the contralateral side to the pathology. 

Pinning

Double pins are posterior, in the sagittal plane, just off midline towards the contralateral side to the pathology. 

Single pin is preferably in the hairline but okay to do in the forehead, at the mid-pupillary line, on the side opposite the pathology. 

Head positioning:

Thrust, extend, rotate

Attach the Mayfield on the inner side, away from the operator. 

Once draped, the Layla bar goes on the side opposite the pathology. The distal arm of the Layla bar is oriented directly towards the operator such that it is parallel with the floor and with the side of the bed. It should be at about the level of the incision. 

The Greenburg retractor is attached on the side of the pathology with the clamp turned such that the short bar is pointed away from the operator.