A CLASSIFICATION OF PLAGIOCEPHALY UTILIZING A 3-DIMENSIONAL COMPUTER-ANALYSIS OF CRANIAL BASE LANDMARKS

Plagiocephaly is a term commonly used to describe congenital forehead asymmetry. Previous classification systems based on the various etiolo gies of dysmorphic crania have been used in an effort to categorize th e patients into groups and to assist in treatment planning. The system most commonly used today was described by Bruneteau and Mulliken in 1 992. The authors separated frontal plagiocephaly into three types: syn ostotic, compensational, and deformational. The present study was unde rtaken in order to define a simple system for classifying plagiocephal y based on Bruneteau and Mulliken's system using the patients' preoper ative craniofacial computed tomography scans. The involvement of the e ntire coronal ring in synostotic plagiocephaly led to the choice of 20 skull base landmarks as the basis of the analysis. Nine lateral landm arks (the superior orbital fissure, the optic foramen, the zygomatic a rch, the greater palatine foramen, the foramen ovale, the mastoid tip, the hypoglossal canal, the external auditory canal, and the internal auditory canal) and two midline landmarks (the crista galli and the in ternal occipital protuberance) were used. The changes that occurred in these landmarks were analyzed in 30 patients. The results demonstrate d that Bruneteau and Mulliken's classification system underestimated t he number of different subtypes of plagiocephaly. As a result, three m ajor types of frontal plagiocephaly and several different subtypes bas ed on the different etiologies were described. Type I plagiocephaly in cludes plagiocephaly resulting from cranial suture synostosis. Type II includes those with a nonsynostotic etiology. Type III describes pati ents with craniofacial microsomia-associated plagiocephaly. Statistica l analysis was unavailable because of the small number of patients in each subtype. With a larger number of patients, we hope to refine this system for use by the surgeon in preoperative diagnosis and surgical planning. The analysis is unique in its ability to quantitate changes from normal on the x-, y-, and z-coordinates, and therefore allows for identification of both horizontal (frontal bone deviation) and vertic al (ear shear) growth disturbances.