Tables:
Determination of Severity of Plagiocephaly
Determination of the severity of plagiocephaly requires precise measurements of the skull using either the cephalic index or anthropomorphic measurements.
Table 1
Specifications for Taking Anthropometric Measurements
Comparative Cranial Landmarks |
Cranial Vault | Left frontozygomatic point (fz) to right euryon (eu) minus right frontozygomatic point (fz) to left euryon (eu) |
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|
Cranial Base | Subnasal point (sn) to left tragus (t) minus subnasal point (sn) to right tragus (t) |
Orbitotragial Depth | Left exocanthion point (ex) to left tragus (t) minus right exocanthion point (ex) to right tragus (t) |
Moderate to severe plagiocephaly is defined as one of the following:
Cranial base (sn – t): >= 6 mm difference between left and right measurements
Cranial vault (fz – contralateral eu): >= 8 mm difference between left and right measurements
Obitotragial depth (ex – t): >= 4 mm difference between left and right measurements
Table 2
Cephalic Index: | Head with (eu-eu) x 100 |
Head length (g - op) |
Moderate to severe plagiocephaly is defined as a cephalic index two standard deviations above or below the mean.
Infants with deformational scaphocephaly will have a lower cephalic index due to a very long and narrow skull deformity.
Infants with deformational brachycephaly will have an increased cephalic index due to a very wide and short skull deformity.
Gender | Age | -2SD | -1SD | Mean | +1SD | +2SD |
Male | 16 days - 6 months | 63.7 | 68.7 | 73.7 | 78.7 | 83.7 |
| 6-12 months | 64.8 | 71.4 | 78 | 84.6 | 91.2 |
Female | 16 days - 6 months | 63.9 | 68.6 | 73.3 | 78 | 82.7 |
| 6-12 months | 69.5 | 74 | 78.5 | 83 | 87.5 |
Assessment of plagiocephaly may be based on anthropomorphic measures of the head, using anatomical and bony landmarks. However, there is no accepted minimum objective level of asymmetry for a plagiocephaly diagnosis.
The following table presents normative values and the mean pretreatment asymmetries reported in large case series.
These may be useful in determining if a significant variation from normal is present.
Table 3
Normative Values
Study | Cranial Base (mm) | Cranial Vault (mm) | Orbitotragial Distance (mm) |
Moss (1) | NR | 9.2 | 7.1* |
Littlefield et. al. (2) | 6.17 | 8.5 | 4.36 |
Teichgreber et. al. (3) | 7.08 | 8.53 | 3.12 |
*In this report, the asymmetry was measured from the tragus to the frontozygomatic point instead of the exocanthion