Background: The term ‘lopsided’ refers to a paired entity in which one side is lower or smaller than the other. In medical terms ‘asymmetry’ is more commonly used. But either description applies to various forms of head shape abnormalities in which there is a discrepancy between the shape of its two sides. Plagiocephaly is the most well known type of a lopsided or asymmetric head shape but it is not the only one.
One type of lopsided head shape is the result of differences in the prominence of the bony temporal line along the side of the head. The bony temporal line of the skull is the origin of the temporalis muscle. Because of this muscular attachment there is a raised ridge of bone along the side of the forehead all the way to the back of the head. The temporal line marks the transition between the top and side of the head and creates a near 90 degree angle between them. When the temporal line is underdeveloped or has less of a prominence the slope of the head as seen frontally from the midline outward becomes more flat.
This form of a lopsided head shape is one of the most noticeable since it is seen frontally. It makes the head look like a part of it has been cut off. A custom skull implant can resolve this lopsided head shape but part of its design must cross the underdeveloped bony temporal line onto the side of the head on top of the muscle.
Case Study: This middle aged male had long been bothered by his left lop sided head shape which had been present since birth. In designing an implant to treat it the maximum projection needed for symmetry was 4mms and a total of 47ccs of volume.. Its long anteroposterior shape was 3x longer than it was wide. It extended from the top of the forehead all the way back to just above the lambdoid suture line.
Under general anesthesia a small posterior scalp incision was made at the location of the back end of the implant’s designed location. A subperiosteal pocket was developed from back to front, crossing over the bony temporal line onto the deep temporal fascia on the side of the head. The implant was inserted, positioned and secured with small self-tapping screws. The incision was closed over a drain.
When seen the next day for head dressing and drain removal the marked improvement in his head shape was apparent.
One type of lopsided head shape, and often the most aesthetically noticeable, is when one temporal line of the skull does not develop as much as the other side. This makes the shape of the head asymmetric as the smaller side has steeper slope or transition into the side of the head. The custom skull implant designed to treat it is much longer than it is wide which makes it possible to place through a remarkably small scalp incision.
Case Highlights:
1) A decreased convexity on one side of the top of the head creates a very visible frontal asymmetry.
2) Lack of development of the bony temporal of the skull creates a more flat transition between the top and side of the head, creating a lop-sided head appearance.
3) A custom skull implant can be designed for the lop-sided head that can be placed through a remarkably small scalp incision.
Dr. Barry Eppley
World-Renowned Plastic Surgeon