There are a variety of basic head shape abnormalities in adults of which the narrow head shape is one of them. The narrow head shape is most commonly perceived by having diminished width from one temporal area to the other in the front view. (bitemporal width) This can often involve the forehead and/or back of the head (biparietal narrowing) for an overall pinched look to the head. Only in the more severe forms is the head longer from front to back which indicates some variant of congenital sagittal craniosynostosis. In some patients it may be a variant of this well known congenital skull deformity or may be an untreated case of actual synostosis.
As an adult the narrow head shape can only be treated by onlay augmentation to help build out deficient width areas. This can not be done by bone cements as the sides of the head are composed of an overlying soft tissue layer (muscle) and not solid bone like the front, top and back of the head. Stripping the muscle attachments on the sides of the head to expose the bone underneath it to place any implant material is a misguided approach that is fraught with postoperative muscle contraction contour problems that can be very difficult to correct secondarily. An effective onlay augmentation in widening the narrow head must sit on top of the soft tissue.(deep temporal fascia) Only a custom solid silicone skull implant design can achieve that effectively with feather edging and without risk of muscle contour issues.
In creating custom skull implants for the more severely narrow head their designs can have a variety of different shapes depending upon where the width is needed the most. One important consideration in the implant’s design is volume. The scalp does not have an unlimited ability to stretch from what is placed underneath it. As a result much of the width addition is often at the back and along the sides of the head where the narrowing is the greatest. Implant volumes in the 150cc range are within the range of what the scalp can stretch to accomodate its placement. Implant volumes approaching 200ccs or greater will require an initial scalp expander procedure.
One of the challenges in the skull implant design for the narrow head is to get enough volume at the narrowest skull area. This is often at the temporo-parietal region. Since this has an obliquely oriented 3D shape, assessing the implant’s design in the two oblique views is necessary.It is important to ensure that the design has a pleasing convex profile to it and has a shape the flows into the surrounding skull areas in a natural appearing manner.
In the front view the head may still have a bit of narrow appearance but the back of the head now has a width that is either equal to or slightly greater than that of the forehead. This brings the head shape into better balance even if the actual head width remains on the low end of normal.
Dr. Barry Eppley