Preparation for Surgery for Ischemic Cerebrovascular Disease in Children

Indications for Procedure

Surgical management of pediatric ischemic stroke includes endovascular and open approaches. There is a lack of consensus regarding optimal patient selection for these procedures, stemming from the relative rarity of ischemic stroke in the pediatric population compared with the adult population (62).

Endovascular

Endovascular techniques include recanalization treatments such as mechanical thrombectomy and intra-arterial thrombolysis (215).

Mechanical thrombectomy in adults

• Use as hyperacute treatment of large vessel occlusion: Endovascular thrombectomy is indicated for adult patients with large vessel occlusion as a hyperacute therapy, generally within 6 hours of stroke onset (216). However, adult patients with disproportionately severe clinical deficits relative to infarct volume (as determined by perfusion imaging studies) may benefit from thrombectomy within 6 to 24 hours of last known normal (DAWN and DEFUSE trial criteria) (217,218).
• Combine with medical therapies: Use of endovascular thrombectomy and standard medical therapy within 6 to 16 hours of last known normal for adult patients has been demonstrated to result in better functional outcomes than standard medical therapy alone, provided these patients have a penumbra region of potentially reversible ischemic tissue that has not yet infarcted (218).

Mechanical thrombectomy in children

The indications described above have not been validated in the pediatric population. A scientific statement published in 2019 by the AHA Stroke Council and Council on Cardiovascular and Stroke Nursing recommended limiting consideration of thrombectomy to select patients (62).

• Consider in patients with high persistent disabling neurological deficit scores: Limit the consideration of thrombectomy to patients with PedNIHSS scores ≥6 (or higher for DAWN trial criteria) (62).
• Consider in patients with radiographically confirmed large vessel occlusion: Note that large vessel occlusion is variably defined as blockage of the intracranial ICA, M1/M2/M3 segments of the MCA, A1/A2 segments of the ACA, intracranial vertebral artery, P1/P2 segments of the posterior cerebral artery, and basilar artery (219).
• Take the patient’s body size into account: The AHA recommended limiting consideration of thrombectomy to larger children, given concerns about smaller groin and cerebral arteries and size-based limitations for contrast dye and radiation exposure (62).
• Involve pediatric stroke neurologists in the decision-making (62).
• Recruit an experienced surgeon: Ideally, a pediatric endovascular surgeon with experience performing thrombectomy in adult stroke patients should perform the intervention (62).
• Thrombectomy may still be an option under the right conditions: Size-based limitations are questionable in pediatrics, as neuroendovascular access of young children is routinely performed, and young age (<1 year and 1-10 years) is notably not a risk factor for complications of neuroendovascular procedures at experienced centers (220). Thrombectomy may thus be reasonable to consider for smaller and younger patients who meet the remaining AHA criteria.

Intra-arterial thrombolysis

Little information is available on the use of intra-arterial thrombolysis in cases of pediatric ischemic stroke. A thoughtful and thorough decision-making process is recommended when considering the use of this treatment modality in children.

• Acute intervention: Intra-arterial thrombolysis requires endovascular catheter-based access and involves local injection of thrombolytic agents at the site of large vessel occlusion; it may act as standalone therapy or as an adjunct to mechanical thrombectomy (221,222). This hyperacute treatment modality is recommended within 6 hours of stroke onset in adult patients (223).
• Not validated in children: Intra-arterial thrombolysis has not been validated in children. Its use has largely been supplanted by safe and effective mechanical thrombectomy, with continuous improvement in devices designed for that indication.
• Contraindications: Intracranial hemorrhage must be ruled out before considering intra-arterial thrombolysis. Moreover, absence of ischemic penumbra, uncontrolled hypertension, presence of cerebral AVM or giant thrombosed cerebral aneurysm, bleeding diathesis, international normalized ratio >1.7, unknown stroke duration, and thrombocytopenia are all contraindications (222).

Decompressive Craniectomy

Open surgery may be employed for patients who experience malignant stroke — that is, a stroke that produces significant cerebral edema, which can cause elevated ICP and place the patient at risk of brain herniation. Malignant stroke may be suggested clinically by severe neurological deficits, signs of elevated ICP, and an impaired level of consciousness, and may be confirmed via imaging studies (225). In these cases, a decompressive procedure such as hemicraniectomy (for MCA-territory stroke) or posterior fossa decompression (for cerebellar stroke) may be required (224).

• Indications for decompressive craniectomy: Decompressive craniectomy requires open surgery and includes both decompressive hemicraniectomy (generally applied in cases of malignant MCA infarction) and suboccipital or infratentorial decompressive craniectomy (applied in cases of malignant posterior circulation infarction leading to significant cerebellar swelling) (226).
• Use of procedure in children: Decompressive surgery is considered effective and potentially lifesaving based on published case series, per the AHA Stroke Council and Council on Cardiovascular and Stroke Nursing 2019 statement on the management of pediatric ischemic stroke (62). The AHA recommends considering decompressive surgery in children with large-volume infarcts (greater than one-half of MCA territory) within 24 hours (early prophylactic hemicraniectomy) (62). Alternatively, the AHA recommends implementing serial imaging and clinical assessments within 72 hours to monitor for signs of significant edema and assess whether surgery is needed (62).

Preoperative Orders

• Stabilization and robust evaluation: Patients with pediatric ischemic stroke should not be taken to the operating room or angiography suite in the absence of adequate preoperative/preprocedural stabilization and evaluation (see Evaluation at Presentation and Intervention at Presentation), including brain imaging to rule out intracranial hemorrhage and laboratory tests. IV tPA or TNK prior to intervention may be considered in select patients (see Adjuvant Therapies for Ischemic Cerebrovascular Disease in Children). Researchers have urged centers to develop pediatric endovascular thrombectomy pathways, two of which are described by Lauzier et al (227).

Anesthetic Considerations

Endovascular

Although conscious sedation may be considered for adult patients undergoing endovascular procedures for arterial ischemic stroke (228), general anesthesia is almost always indicated for children (227). The Society for Neuroscience in Anesthesiology and Critical Care Expert Consensus Statement on the Anesthetic Management of Endovascular Treatment for Acute Ischemic Stroke describes numerous anesthetic considerations for intra-arterial thrombolysis and mechanical thrombectomy. However, there are no explicitly stated considerations for pediatric patients. Its 2014 consensus statement provides the following recommendations (229):

• Ventilation: Perform rapid preprocedural evaluation, titrating the fraction of inspired oxygen (FiO2) to maintain SpO2 >92% and the arterial partial pressure of oxygen (PaO2) >60 mmHg, adjusting ventilation to maintain partial pressure of carbon dioxide (PaCO2) 35 to 45 mmHg.
• Cardiac monitoring: Ensure continuous monitoring of heart rate and cardiac rhythm.
• Blood pressure monitoring: Provide continuous monitoring of blood pressure (considered the ideal method, done via invasive intra-arterial pressure monitoring) or measuring blood pressure at least once every 3 minutes (considered less ideal).
• Systolic blood pressure range: Maintain systolic blood pressure between 140 and 180 mmHg. Note that younger children have considerably lower blood pressure ranges than adults, so the ideal systolic blood pressure range of 140 to 180 mmHg may be unreasonably high for these patients. As detailed in Presentation of Ischemic Cerebrovascular Disease in Children, permissive hypertension, adjusted for age and height, may be reasonable.
• Fluids: Maintain euvolemia.
• Body temperature: Maintain temperature between 35°C and 37°C, using antipyretics or cooling devices as needed.
• Respiratory monitoring: Provide continuous monitoring of SpO2 and end-tidal carbon dioxide (ETCO2).
• Blood coagulation monitoring: Be prepared to administer heparin and protamine as necessary.
• Blood glucose levels: Maintain glucose concentration between 70 and 140 mg/dL.
• Recruit anesthesiologist with relevant experience: Ideally, involve an anesthesiologist with neuroanesthesia expertise.
• Monitor hemodynamics continually postprocedure: Maintain continuous hemodynamic monitoring after the procedure in the stroke unit or PICU.

Decompressive Craniectomy

Decompressive craniectomy is performed under general anesthesia in adults and children (228).

• Hemodynamic monitoring: Patients for whom decompressive craniectomy is indicated may have significantly elevated ICP and therefore may be hemodynamically unstable. Thus, continuous hemodynamic monitoring is necessary (230).
• Manage intracranial hypertension: The anesthesiologist should be prepared to treat intracranial hypertension with hyperventilation, mannitol, and/or hypertonic saline (230).
• Avoid brain hypoxia: Maintain SpO2 >95% by titrating the FiO2 as needed (230).

Devices to be Implanted

Endovascular

The goal of endovascular treatment in cases of thromboembolic stroke is to reperfuse the arterial territory by removing the obstruction. However, if there is intrinsic intracranial vessel disease, this may be ineffective.

• Stents and coils: In a dissection, stent placement or occlusion of the vessel with a coil may be appropriate. In other intracranial arterial diseases, there is evidence in adults that implanted stents are not better than medical therapy (231-233). No such studies exist in pediatric intracranial arteriopathy.

Decompressive Craniectomy

Augmentative duraplasty and cranioplasty often follow decompressive craniectomy. Some complications may require additional intervention and device implantation.

• Augmentative duraplasty: After dural incision, augmentative duraplasty is performed with an allogenic, autologous, or xenogeneic dural graft or with synthetic material (234).
• Cranioplasty: Cranioplasty after decompressive craniectomy is generally achieved via reimplantation of the autologous bone flap but may require a synthetic skull flap if the autologous bone flap is contaminated (235).
• VP shunt in some cases: Rarely, decompressive craniectomy may be complicated by hydrocephalus and CSF disturbances. In such cases, VP shunt placement may be required (236,237).

Ancillary/Specialized Equipment

Endovascular

Endovascular treatment of pediatric ischemic stroke is achieved in the angiography suite and requires specialized equipment in most cases.

• Biplane angiography: Biplane angiography is necessary for optimally safe visualization of vessels in 3-dimensional space.
• Ultrasound: Ultrasound may assist in achieving femoral or radial artery access.
• Additional materials tailored to specific intervention: Depending on the planned intervention, guide catheters, guidewires, microcatheters, microguidewires, stent retrievers, aspiration catheters, or aspiration pumps may be required (238).

Decompressive Craniectomy

Standard neurosurgical equipment is required for decompressive hemicraniectomy and posterior fossa decompression.

• Standard equipment: These open surgical procedures require standard neurosurgical equipment, including a craniotomy/craniectomy instrument set, skull clamp, Raney clips, and a drill (239).