Part of the success of aesthetic skull augmentation with custom implants depends on the stretch of the overlying scalp to accommodate it. While the scalp can be released and it has some natural ability to be elongated there are limits. Unlike using a bicoronal scalp incision (ear to ear) in which the extent of the scalp release and subsequent stretch is greater, custom skull implants use very small incisions for placement. With a much smaller incision the release is more limited and the stretch of the scalp is less.
It is also important to appreciate that everyone’s scalp stretch is different. Thinner scalps have less stretch while thicker scalps have more stretch ability. The most predictive factor of scalp stretch is skin pigmentation. Darker skin pigments have thicker scalps an more scalp stretch. Lighter pigment patients have thinner scalps and limited scalp stretch. There are also gender differences, men have thicker scalps than women and a bit more scalp stretch.
This anatomic knowledge is important in custom skull implants, particularly those of higher volumes. When the size and volume of the skull implant is believed to exceed the patient scalp’s ability to adequately cover it a first stage scalp tissue expander is needed to overcome this limitation.
The key to good scalp expansion is to choose an expander of adequate size or footprint. While no tissue expander can have as large a footprint or the shape of a custom skull implant. But the 15 x 15cm round tissue expander works well for this purpose. It is as big a tissue expander as can be placed through a small scalp incision.
The incision for the placement of the tissue expander will be the same one that will be used for the second stage implant placement. When possible this incision should be placed away from the edge of the tissue expander if possible. This will prevent the incision from being stretched in the expansion. The remote port should be placed under the scalp in an area where the patient can access it for injections. This is usually above the dominant-handed ear. (since they will use their dominant to do the injections)
Incisional closure is done in multiple layers with restorable sutures. Once the incision is closed I access the port with a 25 gauge needle and place 10 to 15cc of saline fluid just to get the inflations started.
The scalp tissue expander is done as an outpatient procedure under general anesthesia. Patients will usually start their own inflation a week later, adding 10cc of saline every 2 to 3 days. The goal is to get the scalp expander volume to the same volume of the custom skull implant design a week or two before the scheduled placement date.
Dr. Barry Eppley
World-Renowned Plastic Surgeon