The skull is typically thought of as a single unified smooth surface throughout its entirety. But the reality is that it is common of 12 different bones that come together and grow to create the overall skull shape. One of these is the parietal bone which is located behind the frontal bone and above the temporal bone. It has an irregular quadrilateral shape. Running across it more superiorly is a portion of the superior temporal line which serves as the attachment for the temporalis fascia and the superior end of the temporal plane.
In skull reshaping surgery the parietal bone has relevance due to a small center projection known as the parietal eminence. Also known as the parietal tuber it is the actual spot where ossification of the skull begins. If it becomes too prominent during development it can be a concern in some men who shave their heads or have very short cropped hairstyles. It can be seen from the front and oblique views as an outward bulge that disrupts the smooth contour of the skull shape.
Reduction of the prominent parietal eminence requires a direct incision either close to it or directly over it. It can not be done from a much more remote scalp incision. This is, of course, an issue for some patients particularly in males that have a shaved head. In close cropped hair it is not a major issue as the small scalp incision can heal very well. Once the incision is made the deep temporalis fascia is exposed.
Based on the anatomy the parietal eminence is partially covered by the temporalis muscle and fascia. Just like in temporal reduction surgery, there is benefit in parental eminent reduction of removing the fascia and muscle that lies over it. This would be the most superoposterior area of the temporalis. This will result by itself in a 3mm reduction of the projection. This then provides access for reduction of the bony eminence using a bone burring technique for an additional 3mms or so of projection reduction.
Once the bone has been sufficiently reduced (the diploic space is beginning to be seen), the scalp incision is closed over a drain. The drain will be removed the following day.
Parietal eminence skull reduction is about reducing a point of projection, not a large amount of skull surface area or thickness. The combination of bone, muscle and fascia collectively provides an adequate reduction of its prominence.
Dr. Barry Eppley
Indianapolis, Indiana