January 16, 2015
Let's talk about the advantages and shortcomings of the linear versus curvilinear incision for retromastoid craniotomies. I've been using the curvilinear incision for the past few years and believe that it offers significant advantages over the linear incision. Let's go ahead and review the positioning and the landmarks for a linear incision, in this case. Landmark that is used for planning the incision involves a straight line from the inion to the posterior root of the zygoma. This straight line marks approximately the location of the transverse sinus. The planned incision is one-third above the transverse sinus or this line and two-third below this line. This marking most likely describes the location of the mastoid groove. The major issue with the linear incision is that after the muscle and the skull flap have been reflected laterally and interiorly, often the muscle and suboccipital scalp end up accumulating under the self-retaining retractor. And this accumulation of the muscle and scalp leads to an increase in the working distance of the surgeon to the deep surgical target of the cerebellopontine angle cisterns. So I'm going to show you the, this disadvantage using an intra-operative video. You can see that the self-retaining retractor has been used here and for this linear incision, which is a right-sided, retromastoid craniotomy, the muscle and scalp have significantly accumulated and have increased the working distance of the surgeon toward the CP angle. This can be especially problematic in patients who have very thick scalp or muscle, as the working distance can be often prohibitive, and the working angles of the surgeon can also become very limited. Knowing these drawbacks, let's go ahead and review an intra-operative photo of the scalp, and the muscle have been reflected inferiorly, using a curvilinear incision, as has been described in this chapter. So here it is, the image that defines the curvilinear incision. Again, this is a left-sided retromastoid craniotomy. The muscle scalp have been reflected inferiorly, so the self-retaining retractor's actually out of the working zone of the surgeon in a linear incision. This retractor is oriented vertically. In a curvilinear incision, this retractor blade, these retractor blades are oriented horizontally and movement of the scalp and the muscle outside of the working zone of the surgeon decreases the working distance toward the CP angle, and also provides the surgeon with more flexible working angles. Thank you.
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