Revascularization for Moyamoya Disease is Performed via Craniotomy
Yes, revascularization for moyamoya disease is performed via craniotomy, not craniectomy. 1 Surgical revascularization procedures for moyamoya disease require a craniotomy (temporary removal of a portion of the skull with subsequent replacement) to access the brain surface for performing either direct, indirect, or combined bypass techniques.
Surgical Approaches for Moyamoya Revascularization
Types of Revascularization Procedures
Direct Revascularization
- Involves creating a direct anastomosis between the superficial temporal artery (STA) and middle cerebral artery (MCA) 1
- Provides immediate blood flow to ischemic brain tissue
- Technically more demanding, especially in children due to small vessel size 1
- Higher risk of cerebral hyperperfusion syndrome (CHS) 1
Indirect Revascularization
- Involves placing vascularized tissue (dura, temporalis muscle, pericranium) in direct contact with the brain surface to promote angiogenesis 1
- Common techniques include:
- Takes weeks to months for collateral circulation to develop
Combined Revascularization
- Utilizes both direct and indirect techniques simultaneously 1
- May provide both immediate and long-term revascularization benefits
Surgical Technique Details
The craniotomy procedure for moyamoya revascularization typically involves:
- Creating a three-quarters osteoplastic temporal craniotomy 3
- Extensive dural opening to expose the brain surface widely 2
- Careful dissection of the STA using a surgical microscope (for direct bypass) 2
- Preservation of temporal muscle and middle meningeal artery for indirect revascularization 2
- Placement of vascularized tissue onto the pial surface (for indirect techniques) 3
- Reattachment of the bone flap to the skull at the end of the procedure 3
Clinical Outcomes and Effectiveness
The Japan Adult Moyamoya (JAM) trial demonstrated that surgical revascularization (bilateral direct bypass) reduced rebleeding rates compared to medical therapy (2.7%/year versus 7.6%/year) in hemorrhagic moyamoya 1. For ischemic moyamoya, while no randomized controlled trials exist, observational data shows significant benefits:
- Reduced stroke frequency after surgery, especially after the first postoperative month 1
- Long-term stroke rate of only 4.3% with minimum 5-year follow-up 1
- Good safety profile with 4% risk of stroke within 30 days of surgery per hemisphere 1
- 96% probability of remaining stroke-free over 5-year follow-up 1
Perioperative Management Considerations
Careful perioperative management is critical to prevent complications:
- Maintain normocapnia (end-tidal CO2 between 35-45 mmHg) to prevent vasoconstriction 1
- Keep patients euvolemic to mildly hypervolemic 1
- Avoid hypotension, hypovolemia, hyperthermia, and hypocarbia 1
- Set systolic blood pressure at or above the patient's asymptomatic baseline 1
- Consider intravenous fluids at 1.5 times normal maintenance rate for 48-72 hours postoperatively 1
- Monitor for cerebral hyperperfusion syndrome, which occurs in approximately 16.5% of patients 1
Potential Complications
- Cerebral hyperperfusion syndrome (CHS): 16.5% incidence overall, higher in adults (19.9%) than children (3.8%) 1
- Transient neurological deficits (70.2% of CHS cases) 1
- Hemorrhage (15% of CHS cases) 1
- Seizures (5.3% of CHS cases) 1
- Chronic subdural hematoma 2
- Postoperative ischemic stroke 1
Key Takeaways
- Moyamoya revascularization is performed via craniotomy, not craniectomy
- The bone flap is preserved and reattached at the end of the procedure
- Both direct and indirect revascularization techniques require craniotomy for access
- Careful perioperative management is essential to minimize complications
- Surgical revascularization significantly reduces stroke risk in moyamoya patients