Cranial index of symmetry: an objective semiautomated measure of plagiocephaly. Technical note.
OBJECTIVE
The prevalence of deformational, or positional, plagiocephaly has increased during the last decade. Treatments vary among centers, ranging from expectant management to orthotic helmet therapy to craniofacial remodeling. This management variability is partially due to a lack of objective methods with which to measure the severity of plagiocephaly, as well as procedures that are not cumbersome or require radiographic studies. A simple and objective method of determining the degree of cranial deformation has been developed.


METHODS
A headband placed around the head was marked with two adjustable points--one denoting the nasion and the other, the inion. A digital camera was used to image the head from a vertex view. The shape of the headband and the area of each hemisphere were then determined by analyzing the image on a personal computer in a semiautomated fashion. A cranial index of symmetry (CIS) was calculated and, by definition, equaled 100% for a perfectly symmetrical head. In this preliminary study, the authors studied eight children referred for evaluation of their plagiocephaly and eight infants referred for noncraniofacial entities. In the unaffected infants the mean CIS was 96.3 +/- 1.3% (+/- standard deviation). In children with clinical evidence of plagiocephaly, however, the CIS was 81.9 +/- 3.4% (p < 0.001). Although the CIS in healthy children was never less than 95%, that in all infants with plagiocephaly was below 90%.


CONCLUSIONS
Although preliminary, this objective nonradiographic measurement of cranial symmetry appears to allow grading of the severity of positional plagiocephaly. The aforementioned methodology may potentially be used as an unbiased means of comparing different treatment modalities in longitudinal studies.
Zonenshayn
Martin
M
Department of Neurosurgery, Weill Medical College of Cornell University, New York, New York, USA.
Kronberg
Eugene
E
Souweidane
Mark M
MM
D003398:Craniosynostoses / Q000473:pathology* / Q000628:therapy; D005260:Female; D006260:Head Protective Devices; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009989:Orthotic Devices