Patient positions for surgery in infants are the same as those used for neurosurgical procedures in other age groups of patients. However certain age-specific factors come into play:
- Heat loss: Prevention of heat loss is important. The ambient temperature in the operating room should be raised until the patient is anesthetized, positioned, and draped. An air blanket is used to maintain the child’s body temperature, and the amount of exposed skin surface is kept to a minimum. Prep solutions can be warmed prior to application to lessen cooling of the infant.
- Head positioning: Rigid skull fixation is generally not possible given the deformational properties of the immature skull. Pin fixation is not recommended in the infant (see below). This can pose difficulties for pressure exerted on the skin of the head of an anesthetized infant during lengthy procedures, and care needs to be taken to address this concern, such as the use of pressure-relieving gel pads or head-lifts at regular intervals during the procedure (if practical).
- Operative navigation: The use of these devices relies on the immobility of the head during surgery, which is difficult. Novel approaches are used, such as bean-bag stabilization with light application of a three-pin fixation device or specially designed infant head clamp. However, technological developments such as magnetic registration/navigation and intraoperative 3D ultrasound updating are invaluable in this age group.
- Retraction: Manual retraction of the infant brain must be undertaken with great care and often is not possible without injuring the delicate tissue. This has been attributed to immature myelination, rendering the tissue ‘softer’ than in older patients. Frontal peripheral white matter myelination, for example, is evident on T1-weighted MRI in infants only from 7–11 months of age (3).
- Blood loss minimized: The circulating blood volume of an infant is approximately 85 ml/kg. Attention should be given to minimizing blood loss at predictable points during the operation such as scalp opening /dissection and bone cutting, with use of techniques such as hemostatic powder applied topically to the exposed galea and waxing of the bone edges. This allows some reserve for unpredictable blood loss during the actual tumor removal.
- Watertight dural closure: If possible, the dural closure is watertight, particularly when a ventricle or cistern has been opened. This can be supplemented by a topical dural sealant. The dermal skin layer is very thin and prone to CSF leak.
- Bone flap: The bone can be held in position either with suture or with absorbable plates. Metal skull fixation devices can migrate through the immature bone, and their use is discouraged. In most cases, an absorbable suture is sufficient to hold a craniotomy flap until healed.
- Skin closure: The mobility of the infant scalp and its elasticity make closure, for the most part, uncomplicated. Absorbable cutaneous suture can be used. The dermal layer is very thin with the galea often being like tissue paper. In addition to using a galeocutaneous layer of absorbable suture material, the author’s preference is to use an absorbable subcuticular stitch supplemented with topical tissue adhesive to close the scalp in an infant.