Background: The projection of the back of the head is an important skull feature. It takes on increased aesthetic significance in patients with short hair or shaved heads, which most commonly are seen in men. With the back of the head is flat patient complain that their head looks unusual or that its looks ‘cut off’. Such flat areas on the back of the head affect one side only or both sides. The flat areas can also be at slightly different locations on the back of the head, some are lower while others can be located higher near the crown area.
It is easy to understand why the plagiocephalic unilateral (one sided) flat back of the head is bothersome due to the asymmetry. But when the back of the head has an overall flatness a disruption of the profile shape of the skull occurs. An increased cranial height may be present and the ratio of the proportions of the skull shape in profile are changed. (nasion-bregma NB and bregma-lambda BL lines) Some may say that the golden ratio of the skull’s profile shape has been altered as the BL distance has been shortened compared to the NB curved lines. Mathematically speaking there is an explanation for why it is aesthetically displeasing. But in the end the patient feels that part of the skull’s shape is missing.
When designing a custom skull implant for the flat back of the head, the most ideal treatment for it, there are two considerations…how much projection and the shape of that projection. While there are limitations to ow much implant projection can be accommodated by the stretch of the overlying scalp, there are no limitations as to its shape. The shape is controlled by the location of the maximum projection needed. It may go directly back in a more horizontal direction or be more angulated upward baed on the center of the skull flattening.
Case Study: This male desired to have his flat back of his head augmented for a more proportionate head shape. His 3D CT scan showed a high flat back of the head shape for which a custom skull implant was designed with its maximum projection located perpendicular to the center of the depth of the flat skull area.
Under general anesthesia and in the prone position a high scalp incision was made in the crown area. A subperiosteal pocket was made inferiorly down to the occipital knob, along the nuchal ridge and out onto the posterior temporal areas bilaterally. The implant compared to the size of the scalp incision always makes it seem like it could never be inserted through such a small entrance …but it can with certain techniques and persistence.
After implant insertion, positioning and screw fixation the scalp incision was closed with resorbable sutures.
The intraoperative before and after profile view of the back of his head showed the significant change in its projection.
In placing custom skull implants to improve overall projection of the back of the head, there are two incision locations. A low central horizontal scalp incision just above the occipital knob area is most commonly used. Patients opt for this location in effort to keep the fine scar line as low as possible. For some patients there may be a low horizontal skin crease which can be used. There are some patients, fewer in number, that prefer a higher scalp incision up around the crown area. For them they feel this is a better scar location. Either location for the incision location is a personal choice and is not affected by the shape of the skull implant. (higher vs low projection profile)
Case Highlights:
1) Adequate projection of the back of the head is an important aesthetic head shape feature in those with short hair or a shaved head.
2) Men dominate back of the head augmentations which can have two main types of variants of the projection needed…directly back and angles more upwards.
3) A custom back of the head skull implant can be placed through either a high crown incision or a low occipital incision.
Dr. Barry Eppley
Indianapolis, Indiana