Preparation for Surgery for Supratentorial High-Grade Gliomas in Children

Preoperative Orders

Medications

• Steroids: Intravenous steroids are typically started prior to surgical intervention, days earlier if there are significant neurological deficits or overt signs and symptoms of increased intracranial pressure.
• Anticonvulsants: Intravenous anticonvulsants should be started on admission for children who present with seizures and may be started immediately preoperatively for those at risk for post-operative seizures based on brain irritation or a transcortical approach.
• Induction antibiotic prophylaxis: The administration of an antibiotic for infection prophylaxis is increasingly becoming an operating room routine, and there is no contraindication for its use for these surgeries. The antibiotic is typically given less than 60 minutes prior to skin incision.

Intravenous fluids

• Rate: IV fluids, typically 1/2 NS + 20 mEq KCl, can be given at maintenance when fasting begins based on the weight of the child as follows: 0-10 kg, 10 ml/kg/hour; 11-20 kg, 40 ml/hour+2 ml/kg/hour; and > 20 kg, 60 ml/hour+1 ml/kg/hour. 
• Rehydrating: Appropriate accommodations should be made for additional fluids based on dehydration or drainage of large amounts of CSF in young infants.

Clamp time for CSF drain

• Carefully monitor if performed: EVDs may be clamped prior to surgery if necessary.  If the ventricle needs to be dilated for intraventricular navigation/exploration/access, the drain should be clamped 8 hours prior to skin incision and drained as needed for symptomatic increased ICP.  Although monitoring the pressure of a clamped drain may be useful, the child’s tolerance is more important.

Surgical site scrub

• Preoperative shampoo: Hair and scalp can be shampooed the night before surgery.  Special agents are not necessary. 
• Removal of objects in hair: EEG electrodes or metallic jewelry should be removed.

Informed consent

Although not every possible intraoperative and postoperative complication can be discussed, the family, guardian, and/or child should be aware of the common concerns regarding supratentorial brain tumor surgery and concerns specific to the anatomic location of any given lesion, including visual loss, seizure, weakness, paralysis, sensory loss, bleeding, infection, impairment of language function, neurocognitive and memory impairment, need for other surgeries such as a shunt, coma, stroke, and death.  Additional attention should be given the patients and families with different language preferences, and every effort should be made to have a language-specific medical interpreter present for the consent process.

Anesthetic Considerations

• Specialize care: Comprehensive pediatric neuroanesthesia, particularly for infants and young children, is mandatory to achieve adequate sedation, particularly when IOM is required, blood volume management will be needed, and maneuvers to control ICP are anticipated.

Devices to Be Implanted

• Ventricular shunt: Permanent CSF diversionary shunts are not placed at the time of tumor resection unless only a biopsy is performed, and there is no blood in the ventricular system. 
• EVD: An EVD may be necessary to control ICP during or after surgery, and may be helpful in allowing for healing of the incision or to slowly challenge the ventricular circulator system prior to potential shunting.
• Cranial fixation: How the craniotomy is closed depends on the surgeon and the patient.  Titanium plates and screws, and wire are reserved for children older than 2 years.  Absorbable cranial fixation plates and pins can be used in younger children, particularly in non-hair-bearing areas, or absorbable monofilament sutures can be used to fix the bone flap.
• Convection-enhanced delivery systems: Some therapeutic protocols may require placement of a small catheter into the area of recurrent, residual, and/or inoperable tumor for the purposes of slowly injecting therapeutic agents into and around the tumor.

Ancillary/Specialized Equipment Required 

• Microscope: Illumination and magnification are mandatory, particularly for deep or intraventricular lesions accessed through small corridors. Depending on patient position, tumor location, and surgeon preference, stereoscopic assistant oculars will allow for two surgeons to work together.
• Ultrasound: The intraoperative ultrasound can dependably identify even deep tumors, assess the progress of resection, identify nearby cysts or ventricles, and help identify important changes during surgery, such as collapse of brain not exposed by the craniotomy or the development of a hematoma.
• Endoscope: The endoscope can be utilized in place of a standard craniotomy for biopsy, or in some cases, resection of intraventricular or periventricular tumors. This will minimize cortical injury and retraction in children with supratentorial brain tumors in addition to allowing for management of hydrocephalus with an ETV. The endoscope may also be used to augment open tumor resections, inside or outside the ventricle, both as a visual tool and as a working port.
• Image-guided navigation and stereotaxy: Although real-time intraoperative imaging, discussed below, has become commonplace, the accuracy, ease of use, and reproducibility of navigational systems that use preoperative imaging play a vital role in localizing and minimizing craniotomies, cortical incisions, and guide the surgeon to the lesion with great accuracy. Recent advances in these systems use surface registration in lieu of fiducials. This allows for the use of preoperative imaging performed days or weeks before the planned surgery. Systems utilizing electromagnetic coils and registration can be used when rigid head fixation is not possible.
• Intraoperative CT and MRI: Intraoperative imaging gives the added benefit of real-time imaging to help verify position within the tumor or brain, extent of tumor resection, and the development of edema or hemorrhage, even in areas of the brain remote from the surgery. The images from many of these systems also can serve as reference points for image-guided localization and navigation.