The Operation for Cavernous Malformations in Children

Patient Positioning

• Varies: Positioning of the patient depends on the location of the lesion and the surgical approach.
• Use of head holder optional: The use of a head frame with pins is optional. If skull pins are used on young children, care should be taken to avoid fracture, penetration, or deformity of the skull.

Surgical Approach

• Shortest route that avoids functionally important structures: The principle of surgical approach is to choose a point where the lesion is closest to the brain surface and to choose the safe entry zone of the brainstem. A two-point method has been described for selection of the appropriate approach to a brainstem lesion (8). A single point is placed at the center of the lesion, and a second point is placed at the margin of the lesion where it comes closest to or abuts the pia or ependymal surface. A line connecting the two points is extended superficially and delineates the best approach to the lesion. The surgical approach that most closely mimics the two-point approximation is used to resect the lesion.
• Mapping for functional structures helpful: Intraoperative neurophysiological monitoring is helpful to find the safe entry zone, especially in the floor of the fourth ventricle.

Intervention

• Remove hematoma carefully: The cavernous malformation proper is often mixed and buried inside the old hematoma products. Careful dissection is needed to achieve complete excision of the cavernous malformation.
• Look for vascular bundle and coagulate: A vascular bundle is usually present at the deep part of the lesion. This situation should be anticipated, and hemostasis should be secured.
• Remove hemosiderin-stained tissue if possible: For epilepsy surgery, if the location allows, i.e., not a critical eloquent area, removal of the hemosiderin-laden gliotic tissue has been recommended for better seizure outcome (27).
• Leave DVAs undisturbed: DVAs are frequently associated with deep-seated cavernous malformations. These veins often contribute to the normal venous drainage of the deep brain structures. Most authors recommend sparing these veins to avoid neurological deficit (19).

Closure

• Routine: The resection cavity should be carefully inspected for complete resection and for hemostasis before closure. The craniotomy is closed in routine fashion.