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Parents: what is CVAI & CI?

Since 1995, a worldwide prevention program has been initiated to reduce Sudden Infant Death Syndrome (SIDS). The most important advice therein: put your child to sleep on their back! Since then, there has thankfully been a significant decrease in SIDS. However, there has been a simultaneous increase in cases of misshapen or flattened heads. To help you and your baby, we have developed Skully Care. Skully Care provides a percentage score after you take a photo. What does that mean, and how should you interpret it? What is CVAI and what is CI?


Skully Care assists in measuring, tracking, and advising on plagiocephaly and brachycephaly. When you or your therapist takes a photo with Skully Care, we return measurements in percentages with CVAI and CI. But what are CVAI and CI? What do they mean and how should you interpret them?


CVAI and CI: An Introduction

CVAI and CI are measurement formulas, developed by Loveday and De Chalain (2001). They are now the global standard and are used by researchers and pediatricians for babies with misshapen or flattened heads. Skully Care has integrated CVAI and CI due to their international reputation.


CVAI (Cranial Vault Asymmetry Index) focuses on cranial asymmetry, i.e., when the head is unevenly flattened (plagiocephaly). CI (Cephalic Index) deals with flattening at the back of the head, making the head appear wider than normal (brachycephaly).


CVAI and CI: How are they calculated?


The formulas by Loveday & De Chalain are:


CVAI(%) = (a-b)/b x 100


where a is the longer line from line 1 or line 3, and b is the shorter line from line 1 or line 3.


CI(%) = length of line 4 / length of line 2 x 100


CVAI and CI: The Scale

The Plagiocephaly Severity Scale classifies the severity of skull deformation in 5 levels. The Brachycephaly Severity Scale classifies the severity in 4 levels. Together, one can quickly determine the severity of the asymmetry.


Plagiocephaly Severity Scale

- Level 1: CVAI <3.5% - Head is hardly/not misshapen

- Level 2: CVAI 3.5-6.25% - Head is slightly misshapen

- Level 3: CVAI 6.25-8.75% - Head is moderately misshapen

- Level 4: CVAI 8.75-11% - Head is noticeably misshapen

- Level 5: CVAI >11% - Head is very noticeably misshapen


Brachycephaly Severity Scale

- Level 1: CI <90% - Head is of normal width

- Level 2: CI 90-95% - Head is slightly wider than normal

- Level 3: CI 95-100% - Head is moderately to noticeably wider

- Level 4: CI >100% - Head is very noticeably wider


An Example

A baby has a preference for the left side of the head, which results in left positional plagiocephaly. This hampers the development of the part of the skull where the baby lies (left backside) but allows development on the other sides. This results in a parallelogram-shaped skull. The longer diagonal length is 6.2% longer than the shorter, which barely falls into level 2, mild positional plagiocephaly on the left side.


If a baby has brachycephaly, the head looks quite round, while the ideal shape is more elongated. This shape is dependent on genetic components and cultural differences. Lines 2 and 4 determine the severity of brachycephaly.


If these lines were of equal length, the CI would be 100%, severe brachycephaly. For most researchers, the cutoff for brachycephaly is set at 90%.


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