Neurosurgery notes/Procedures/Cranial procedures/Vascular procedures/Vascular bypass/Indirect revascularization procedures

Indirect revascularization procedures

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Vascular bypass

General

  • Usually reserved for younger patients (suggested cut off age ≈ 15 years).
  • Use in paeds more as
    • Paeds have smaller vessels (<1mm)
    • Paeds have more ischaemic brains to induce neoangiogenesis from the revascularization procedure
  • May be combined with STA-MCA bypass.
  • Promote new capillary network formation
  • If the PbO2 of the brain isnt low its likely indirect revascularization will not work

Pros

  • Recipient vessel size not important
  • As revascularization occurs over with time, new flow into ischaemia area is of smaller volume → ischaemic brain more able to accommodate this low flow
  • Easier

Cons

  • Delay in revascularization
  • Indirect revascularization procedures improve blood flow in the MCA distribution, but not ACA circulation. This may be rectified by:
    • Simple placement of frontal burr holes with opening of the underlying dura and arachnoid
    • “Ribbon EDAS” where a pedicle of galea is inserted into the interhemispheric fissure on both sides

Includes

Encephalomyosynangiosis (EMS)
  • Laying the temporalis muscle on the surface of the brain
  • May cause problems with muscle contractions during talking and chewing, and neural impulses on surface of brain
10 Pediatric Moyamoya Disease | Neupsy Key
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Frontotemporal incision with frontotemporal craniotomy
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Flap of temporalis & fascia cut on 3 sides. Dura cut in cruciate fashion. Temporalis muscle flap sutured with dura.
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Cross-sectional view of split-thickness temporalis muscle graft, seen under the edge of craniotomy flap. Inverted dura and muscle flap sutured together.
Encephaloduroarteriosynangiosis (EDAS)
  • Suturing the STA with a galeal cuff to a linear defect created in the dura.
  • Variations on this technique include splitting the dura
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Incision along parietal STA craniotomy with 2 burr holes, top and bottom to allow STA
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Cruciate dural opening, MMA branches preserved. Suture anchoring the galea and fat of the STA to the pia adjacent to the cortical MCA branch
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Bone flap reconstruction, STA under the bone flap through expanded burr holes.
Encephaloduroarteriosynangiosis | Neupsy Key
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Encephaloduroarteriomyosynangiosis (EDAMS)
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Frontotemporal incision encompassing the parietal STA and temporalis muscle
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Strip temporalis muscle sutured to dural, STA branches lying on brain
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Bone flap reconstruction with opening inferiorly for passage of artery and muscle
Encephalodurosynangiosis (EDS)
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Craniotomy and scalp incision along with STA frontal and parietal branch
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Craniotomy deep to temporalis muscle with dural incision shown in blue which preserves the 2 Middle Meningeal artery branches.
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Leaflets of Dura inverted, tucked under followed by replacement of bone flap
EncephaloGaleosynangiosis (EGS)
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Galea below superior temporal line split into the superficial temporal fascia in which the STA lies and deep temporal fascia covers temporalis muscle.
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A wide cuff of galea is kept with the STA branches and rotated to place the artery over the cortex. Galea cuff sutured with dura.
Multiple burr holes
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Retrocoronal bilateral incision
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Multiple burr holes (8-10) placed on frontal, parietal, temporal regions of affected side
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Dural incision taken. Pericranial flap placed below the dura
Omental transposition
  • Either as a pedicle graft or as a vascularized free flap.
  • Pros: higher potential to revascularize ischemic tissue than above procedures,
  • Cons: Greater risk of mass effect from the thickness of the omentum
Stellate ganglionectomy and perivascular sympathectomy
  • Unproven that this increases CBF permanently

Outcome with surgical treatment

  • Neurologic status at time of treatment generally predicts long-term outcome.
  • Mortality rate in adults (≈ 10%) is higher than for juveniles (≈ 4.3%).
  • Bleeding
    • 56% of children
    • 63% of adults.
  • Treatment the prognosis is good in 58%.