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Background: The brow bones are seen as the protrusions above the eyes that many assume are made up of solid bone. But that is only true for the outer calfs or tail of the brow bones. Half of the brow bones, the inner half on each side, is composed mainly of air because their shape represents the development of the underlying  frontal sinuses. That has great relevance when it comes to their surgical reduction and is why the ‘setback bone flap’ technique is frequently used. The overlying bone cover is too thin to do a burring reduction method.

In the development of the frontal sinus they do so as paired structures separated by an intervening bony septum. While the frontal sinuses develop in a paired fashion they are rarely ever symmetric. One side is usually bigger than the other and this has been visualized for a long time with plain sinus films.

But despite being asymmetric in size the outer appearance of the brow bones is usually symmetric. This is because the asymmetry is usually in the width or height of the frontal sinus development not in its outward horizontal projection. But when an external brow bone asymmetry is seen the frontal sinus over development has affected its outward projection as well.

Having large symmetric brow bones is one type of aesthetic forehead issue. But having one bigger than the other is a more unique, but no less, aesthetically disturbing concern.   

Case Study: This young male was bothered by his asymmetric brow prominence with the right side having a greater protrusion in its medial half. The four methods of incisional access were discussed and he opted for a trans coronal approach for correction. 

Under general anesthesia a transcoronal scalp incision was performed to expose the brow bones where the right brow bone asymmetry was evident. The overlying frontal sinus wall was removed with a reciprocating saw, reshaped and inlaid back into the exposed frontal sinus after reducing all edges of the surrounding bone. A  surgical collagen mesh layer was placed over all edges and the scalp closed over a drain. 

The intraoperative before and after from the top and submental views showed the improvement in the medial brow bone symmetry.

There may be some cases of brow bone asymmetry in men and more frequently in women where a burring technique alone may be sufficient. But in men the most important issue is not how the brow bone protrusion is reduced but the access to do so. Like all aesthetic surgeries it almost always comes down to tradeoffs…is the scar needed to do the surgery a worthy tradeoff for the improvement in brow bone symmetry .Each patient must make that decision for themselves. 

Case Highlights:

1) Significant asymmetries in the brow protrusions is a result of excessive pneumatization of one side.

2) Reduction of the unilaterally enlarged brow bone in a male requires a bone flap technique in most cases.  

3) There are multiple transcutaneous methods to approve the brow bone from a direct, mid-forehead, hairline (pretrichal) and coronal scalp incisions, each with their own advantages and disadvantages.

Dr. Barry Eppley

Indianapolis, Indiana

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