The Operation for Ischemic Cerebrovascular Disease in Children

Patient Positioning

• Endovascular treatment: The patient should be supine with the head toward the biplane imaging apparatus.
• Decompressive hemicraniectomy: For decompressive hemicraniectomy, the patient should be supine with the head rotated to the contralateral side. A pad can be placed under the ipsilateral shoulder to tilt the head up (226,239).
• Suboccipital or infratentorial decompressive craniectomy: For suboccipital or infratentorial decompressive craniectomy, the patient should be positioned in the prone or semi-prone (lateral) position (226). A head holder may be used to stabilize the head during surgery.

Surgical Approach

Endovascular

Ultrasound may be used to facilitate access to the femoral artery. The guide catheter is advanced into the ICA or the vertebral artery on the appropriate side. A balloon guide catheter may be used to restrict proximal flow and prevent distal embolization (240).

• Stentriever thrombectomy: For stentriever thrombectomy, the clot is crossed with a microcatheter, and the stentriever is deployed by unsheathing it from the microcatheter (66,238).
• Aspiration thrombectomy: The ADAPT technique involves multiple steps. First, the clot is crossed with a microguidewire and microcatheter (241). Next, an aspiration catheter of the largest possible caliber is passed over the microcatheter until it is directly adjacent to the clot site. Then the microguidewire and microcatheter are removed and aspiration is applied. Confirmation of lack of flow indicates proper contact with the clot itself (240,241). Newer aspiration catheters are softer and have a larger internal diameter with the same outer diameter, allowing them to pass without microcatheter or microwire guidance into the occluded vessel.

Decompressive Craniectomy

Decompressive hemicraniectomy and posterior fossa decompression, the latter of which requires suboccipital or infratentorial decompressive craniectomy, both require a careful approach.

• Decompressive hemicraniectomy, incision: The incision takes the shape of a wide curve or question mark. It usually begins anterior to the tragus and below the zygoma, curving around the superior pinna, extending posteriorly and then superiorly, and finally extending to the frontal area behind the hairline (226,239).
• Decompressive hemicraniectomy, craniectomy: After incision, the scalp flap and temporalis muscle are raised and dissected from the underlying bone (226). To promote wound healing, the length and width of the flap should be similar; a long narrow flap may have compromised perfusion at the apex of the incision (239). Burr holes are placed, and craniectomy proceeds along the contour of the flap to achieve bony decompression (226).
• Suboccipital or infratentorial decompressive craniectomy, incision: A linear midline incision is created between the inion and superior cervical spine (226).
• Suboccipital or infratentorial decompressive craniectomy, craniectomy: Dissection of the muscular layer proceeds in the midline avascular plane. Suboccipital burr holes are placed, and craniectomy proceeds into the foramen magnum. Authors have recommended removal of the posterior arch of the atlas as well, to avoid tonsillar herniation (226).

Intervention

Endovascular

The aim of endovascular thrombectomy is recanalization of the affected vessels, which may be achieved with a stentriever or aspiration catheter. Effectiveness of recanalization is then assessed.

• Stentriever thrombectomy: After the stentriever is deployed, the device integrates into the clot for up to 4 minutes, after which the stent (containing the clot) and microcatheter are retrieved (238). Angiography can then be performed to assess the effectiveness of the recanalization.

DSA images collected during mechanical thrombectomy of a patient with pediatric ischemic stroke: The patient is a 15-year-old male with cardiomyopathy and ventricular assist device who presented with acute neurological decline. This patient underwent non-contrast head CT and was found to have occlusion of the left ICA bifurcation. (A) Contrast was injected into the left ICA; on this AP view, there is no filling of the left ACA, left MCA, or their branches (yellow arrow). (B) A reperfusion catheter is observed within the left ICA, just proximal to the site of occlusion. (C) On this lateral view, contrast was injected into the left ICA, with no filling of the left ACA or left MCA observed. (D) Lateral and (E) AP views of contrast injection into the left ICA after deployment of the stentriever show some filling of the left MCA. (F) After the second pass of the stentriever, flow is observed in the left ACA and left MCA (yellow arrow), with less than half of the left ACA and left MCA territories visualized (modified treatment in cerebral infarction — mTICI — grade 2a reperfusion). (Images courtesy of Dr. Fabricio Goncalves and Caroline Davies of the University of Alabama at Birmingham Heersink School of Medicine.)

• Aspiration thrombectomy: After proper placement of the aspiration catheter is verified, aspiration is again applied via syringe or aspiration pump, and aspiration is maintained while slowly withdrawing the aspiration catheter (along with the clot) (240,241). Rescue therapy via stent retriever thrombectomy may be required if the ADAPT technique fails (238). Angiography can then be performed to assess effective recanalization.
• Thrombolysis in Cerebral Infarction grading system: Angiographic data can be used to assess the effectiveness of recanalization achieved via thrombectomy and/or intra-arterial thrombolysis. Such an example is the modified Thrombolysis in Cerebral Infarction grading system score shown below (242):

• Effective recanalization: Generally speaking, effective recanalization is defined by Thrombolysis in Cerebral Infarction Grade 2b or higher perfusion. The time between groin access and achieving at least Grade 2b perfusion is known as the recanalization time (241). The adult literature has significant variability in these classifications as well.

Decompressive Craniectomy

Following the incision and craniectomy, durotomy is performed to decrease ICP. Generally, opening of the dura with an expansile dural replacement either without or with watertight suturing can provide the best decompression after bone opening.

• Decompressive hemicraniectomy, durotomy: Once bony decompression has been achieved, durotomy is performed with a stellate or a U-shaped incision approximately 1 cm from the bone edge (239). Augmentative duraplasty is performed or separation material employed to cover the exposed brain (226).
• Suboccipital or infratentorial decompressive craniectomy, durotomy: Durotomy is performed with a Y-shaped incision, which is followed by augmentative duraplasty (226).

Closure

Endovascular

Hemostasis must be achieved at the end of the procedure. The mechanism to achieve hemostasis depends on the access site and patient factors.

• Femoral artery access: Hemostasis at the groin access site can be achieved via manual compression, and a compression bandage can be used in patients of adequate weight. If the patient received tPA or TNK, some surgeons prefer to use a closure device to decrease hemorrhagic risk despite the chance of femoral artery ischemia.
• Radial artery access: Radial access closure generally involves a Velcro-secured, air-inflated balloon wristband.

Decompressive Craniectomy

Following durotomy and duraplasty, hemostasis must be achieved. This is followed by closure and bone flap storage. Delayed cranioplasty follows decompressive craniectomy when deemed appropriate.

• Closure: Closure following decompressive craniectomy must avoid brain compression: excellent hemostasis must be achieved. The edges of the temporalis muscle may be approximated loosely with sutures (in the case of decompressive hemicraniectomy); a subgaleal wound drain should be placed, the galea closed with absorbable sutures, and the skin closed with staples or nonabsorbable sutures (239).
• Bone flap storage: For both types of decompressive craniectomy, the bone flaps are stored by cryopreservation or implantation into an abdominal subcutaneous pocket for future autologous cranioplasty (226,235).
• Indicate absent bone flap: The patient’s absent bone flap should be clearly marked or otherwise indicated (226,239).
• Cranioplasty: Cranioplasty is generally not performed until several weeks or months after the craniectomy and may require bone substitute; there is considerable debate regarding the optimal timing of cranioplasty, but some authors have suggested approximately 3 months postcraniectomy to optimize functional outcomes and minimize the risk of infection (235,239). Early cranioplasty may be needed in situations of syndrome of the trephined (which is also known as sinking skin flap syndrome) or external hydrocephalus.