Background: Flattening of the back of the head is one of the common aesthetic skull deformities. Many of these are mild and are likely caused by how one slept as an infant. But others are more severe and are caused by a genetic tendency based on ethnicity or familial tendencies or even from lambdoidal synostosis. These more severe flattening of the back of the head are known as brachycephaly and look like the back of the head has been cut off.
While brachycepahaly can be treated by cranial vault remodeling as an infant, the time available to do such bone-based surgery passes quickly. As an older child, teen or adult, such bone-based surgery is not an option. At these ages the concept becomes one of stretching out the overlying scalp by adding to the bone on top of it. While only bone cements have been used in the past to do so, they have numerous limitations and have been replaced by custom made implants based one the patient’s 3D CT scan. Such an approach offer a much better result (smoothness and contour) with a smaller incision length to do so.
A large skull implant augmentation and the amount of increased projection that can be achieved is ultimately determined by the amount of stretch that the scalp will permit. This will vary by a number of factors (scalp thickness, natural elasticity and incisional length access) but, as a general rule, the scalp can safely accommodate a 10 to 12mm immediate increase in central projection. (with a long side taper) Greater amounts of implant projection will require a first stage scalp expansion to accommodate it.
Case Study: This 70 year-old man had been bothered his whole life by the flatness of the back of his head. A 3D CT scan showed how flat the back of his hand was with a complete lack of convexity. He wanted a significant amount of projection which he estates would be close to an inch.
A custom occipital skull implant was designed from his 3D CT scan based on giving him a a more pleasing convexity. This measured out to be 22mms of central projection. Because of this amount of increase a first-stage scalp tissue expander was placed. Over a six week period a total expander volume of 200cc was instilled. This correlated with the 200c volume that the custom implant had.
As a second stage procedure the tissue expander was removed and the custom skull implant placed. The amount of scalp expansion was the perfect amount needed for an implant of this size that allowed for a competent scalp incision closure. His immediate after result showed the amount of projection added to the back of his head.
Besides the good improvement obtained in back of the head projection increase is that the patient was willing to do so at 70 years of age. This is a testament to the degree of how much this congenital skull deformity bothered him and the lengths he was willing to go to improve it.
Highlights:
1) Severe flattening of the back of the head is known as brachycephaly.
2) For significant increased projection of the back of the head a first stage tissue expander is needed.
3) A second state custom skull implant can increase the projection of the back of the head by 25mm or an inch.
4) Age is not a limitation for skull augmentation surgery.
Dr. Barry Eppley
Indianapolis, Indiana