Preparation for Surgery for Intracranial Aneurysms in Children

Indications for Procedure

The operative goal is selective occlusion of the aneurysm to prevent rebleeding, while preserving all normal vessels and avoiding additional injury to the brain. Given the high life expectancy of children, the treatment should have low morbidity and mortality risks and should provide durable long-term cure.

Ruptured or symptomatic unruptured intracranial aneurysm

• Emergency surgery in case of impending herniation: In this setting, emergent surgical treatment of the aneurysm may be required; this allows for evacuation of hematoma to relieve mass effect or decompressive craniectomy to treat intracranial hypertension. An EVD may be required.
• Urgent surgery in other cases: When the initial clinical status is stable, surgery or endovascular treatment within 24 to 72 hours is preferred in ruptured or otherwise acutely symptomatic aneurysms.

Incidental intracranial aneurysms

Treatment indications are subject to controversy, even in adults. Findings of large studies with older patients, including the International Study of Unruptured Intracranial Aneurysms (103,104), have been called into question (105), and current guidelines for older patients suggest the consideration of numerous factors (97). Important aspects in favor of treatment are listed below; these factors can be used when counseling parents in the rare event of an incidental pediatric aneurysm (98).

• Previous rupture of a different aneurysm: One study revealed that a history of subarachnoid hemorrhage was a significant predictor (hazard ratio = 7.3) of aneurysm rupture (106).
• Positive family history: Family history of intracranial aneurysms has been associated with higher risk of rupture in the context of small unruptured intracranial aneurysms (107).
• Aneurysm size >7 mm: Larger aneurysms (>7 mm in diameter) are associated with increased risk of rupture. One study revealed the following hazard ratios: 7-9 mm, 3.35; 10-24 mm, 9.09; and >25 mm, 76.26 — suggesting the risk of rupture increases with increasing aneurysm size (108).
• Aneurysm lobulation: Aneurysm multilobulation is associated with higher risk of rupture. The presence of multilobulation was a significant predictor (odds ratio = 17.4) of rupture in one retrospective study (109).
• Aneurysm growth or de novo occurrence on serial imaging: The presence of aneurysm growth on serial imaging was a significant predictor (odds ratio = 55.9) of rupture in one retrospective study (109).
• Life expectancy: Many cerebrovascular specialists prefer conservative management in the setting of low life expectancy due to chronic or malignant disease (98). Patients with a higher life expectancy may derive more benefits from intervention and may be better surgical candidates, although other factors (including the risks of intervention) must be considered.
• Low individual risk of treatment: Low individual risk of treatment (particularly in patients who are expected to derive substantial benefits from intervention) is supportive of treatment, although other factors must be considered, such as the expected risk of nonintervention (98).

Preoperative Orders

• Vital signs: Blood pressure (aim is normotension for age), heart rate, and oxygenation should be continuously monitored.
• CSF drainage parameters: When an EVD has been inserted prior to surgery, the aim should be physiological ICP for age. Theoretically, rapid shifts in CSF and pressure may provoke rebleeding due to a transmural pressure change.
• Medication: While oral or IV nimodipine is standard treatment in adults with ruptured aneurysms, great care should be taken when administering this drug to children. There are no controlled trials in children, and data from small series suggest a substantial risk of induced arterial hypotension (90).
• Antibiotics: IV antibiotics are given at induction.

Anesthetic Considerations

• Anticipation of blood loss: Adequate vascular access and availability of crossmatched blood products is of paramount importance. The use of a cell saver system should be discussed.
• Blood pressure control: Normotensive blood pressure should be aimed for, although temporary hypotension during clipping might be required in selected cases.
• Cardiac standstill ± hypothermia during clipping: This maneuver is considered helpful in rare circumstances (101). More recent approaches with lower morbidity may include transvenous cardiac pacer wires to induce a low cardiac output from tachycardia, or adenosine administration (which is less predictable but does not involve additional invasive procedures) (110,111).

Devices to Be Implanted

• Vascular clips: An array of aneurysm clips should be readily available.

Ancillary/Specialized Equipment

• Intraoperative angiography: Microscope-based ICG angiography provides real-time information about patency of vessels and aneurysm occlusion, resulting in clip repositioning in 9% of cases (112).
• Micro-Doppler sonography: This modality can be used to assess the patency of vessels and confirm aneurysm obliteration (113,114).
• Intraoperative neuromonitoring: This might be useful to detect ischemia at a very early stage and thus indicate the need for clip reevaluation and repositioning (115).