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The measurement results, the explanation

Since 1995, a prevention program has been started worldwide to reduce cot death. The most important advice in this: put your child to sleep on the back! Fortunately, there has been a large decrease in SIDS since then. However, at the same time there was a considerable increase in crooked heads and / or flattening of the back of the head. We have developed Skully Care to help you and your baby. Skully Care will give you the result in percentages after you have taken a photo. What does that mean, how should you interpret it? What is a CVAI and what is a CI?


The explanation


The CVAI and CI are measurement formulas that are used worldwide by researchers and practitioners of babies with a crooked or flattened head. Because of this international reputation, the CVAI and CI are used in Skully care.

Loveday and De Chalain were the first to describe the CVAI in their 2001 study (source 1).


The CVAI is about the skull asymmetry or the head is obliquely flattened (Plagiocephaly). The CI is about the flattened right back, making the head wider than normal (Brachycephaly).

CVAI en CI hoe wordt het berekend.jpg

Figure 1. Skully care automatically measures the length of the four lines.

Formule Engels en Spaans.png

The formula is as follows:





Diagonal a = longest diagonal

Diagonal b = shortest diagonal

Cut-off point for significant plagiocephaly is 3.5%.

Fromule Engels 2.png

An example:

The baby in the photo (figure 1) has a preferential head rotation to the left, this is clearly visible. Skull growth is inhibited in the lying spot on the left-back. The growth in other places continues and this creates a crooked head. The content of the head remains the same, so that the brain has enough space. The diagonal from back left to front right is shorter than the other diagonal from back right to front left. The CVAI indicates how much that is. The CVAI for this child is 6.2%, which means that the longest diagonal is 6.2% longer than the shortest. It just falls into level 2 (figure 2), a mild Plagiocephaly. You may think: the head looks round, while the ideal shape is more elongated. This shape depends on genetic components and cultural differences. The line from ear to ear is slightly shorter in this child than from nose to back of head. If these lines were the same length, the CI would be 100%, which is a clear flattening. In this child the CI is 94%, a mild flattening (Brachycephaly). The cut-off point for Brachycephaly is set at 90% by most researchers.


Cut-off points and scale:

Plagiocephaly Severity Scale (source 2) classifies the severity of the cranial deformation into 5 levels. In this way it is quickly clear how bad the flattening is.

1. Normal

2. Mild

3. Moderate

4. Clear

5. Very clear


The Brachycephaly has 4 levels:

1. Normal

2. Mild

3. Moderate to clear

4. Very clear


In 2006, researchers from Children's Healthcare of Atlanta developed the 'CHOA' or Children's Healthcare of Atlanta Plagiocephaly severity scale (Figure 2).

Figure 2. Editing of Children's Healthcare of Atlanta plagiocephaly severity scale.

Translation and editing: EJ van der Grift, pediatric physiotherapist and founder Skully care.


  1. Benjamin PT Loveday, BHB; Tristan B. de Chalain, MD, FRACS (Plast)
    Active Counterpositioning or Orthotic Device to Treat Positional Plagiocephaly?

  2. Mark A. Holowka, MSPO, CPO, Andrew Reisner, MD, Brian Giavedoni, MBA, Janet R. Lombardo, MBA, CPO, and Colleen Coulter, DPT, PhD
    Plagiocephaly Severity Scale to Aid in Clinical Treatment Recommendations

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