Figure 3-28.
Step 2. There are three bone flaps that can be used in a subfrontal approach to the third ventricle A, The standard frontal craniotomy is easiest to perform. B, Removing the orbital ridge unilaterally greatly decreases the need for frontal brain retraction. C, In massive tumors that have lateral extensions, removal of both orbital ridges may be advantageous. In this case, both frontal lobes are retracted to provide excellent exposure for not only the rostral but also the lateral extensions of the neoplasm. However, this approach has several disadvantages, including the time required to remove both orbital ridges, the need to deal completely with the frontal sinus, and the likely loss of both olfactory tracts even if they are carefully dissected off the frontal lobes. All three craniotomies can be achieved through a bicoronal incision.
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