Unusual cranial aspects of the Apert syndrome.

Frank cloverleaf skull is found in approximately 4% of Apert-syndrome infants. However, the usual Apert skull and its cloverleaf form are spectral in nature. In all patients, the temporal bones are obliquely situated, and the degree to which this is so determines whether no, mild, moderate, or severe cloverleafing will occur. True encephalocele rarely is found in the Apert syndrome, but pseudoencephalocele in the frontal region sometimes is confused with it. Because the Apert calvaria at birth is characterized by a widely gaping midline defect, the midfrontal region of the brain is not covered by bone during early infancy. However, with time, closure of the midline defect occurs by coalescence of bony islands, thus covering the pseudoencephalic region. Also discussed in this paper are (a) atypical calvarial development with patency of the coronal sutures in one case, (b) size and position of the temporal muscles, and (c) size and position of the superficial temporal fat pads.