In 1995, a global initiative was launched to reduce the risk of cot death, and one of the key recommendations was to put babies to sleep on their backs. This simple advice led to a dramatic decrease in cases of Sudden Infant Death Syndrome (SIDS). However, as a result, there has been an increase in babies developing flat heads or asymmetrical head shapes, which is known as plagiocephaly and brachycephaly.
Skully Care assists in measuring, tracking, and advising on plagiocephaly and brachycephaly. After taking a photo by using our App, it will give you the results in percentages. But what do these numbers mean, and how should you interpret them? Let’s dive into the details, explain the measurement results, and explore the CVAI and CI used to classify the severity of your baby’s head shape.
A short explanation
In our app, we use two measurements to determine whether a baby has a flattened head. The CVAI indicates the degree of flattening on the sides of the head, which is associated with plagiocephaly. The CI measures the flattening on the back of the head, which can indicate brachycephaly. Both values are displayed as percentages. After your measurement, you’ll receive the result in a clear graph, allowing you to quickly see if there’s flattening and, if so, which type.
What are the CVAI and CI?
The CVAI (Cranial Vault Asymmetry Index) and CI (Cephalic Index) are well-established methods used by researchers and professionals worldwide to assess skull deformities in babies. Due to this international reputation, CVAI and CI are used in Skully care. The CVAI was first introduced by Loveday and De Chalain in their 2001 study (source 1)
CVAI helps measure the asymmetry of the skull when the head is obliquely flattened, which is a common feature of plagiocephaly.
CI, on the other hand, focuses on how flattened the back of the head is, which can make the skull appear wider than normal, a condition known as brachycephaly.
How Does Skully Care Measure Your Baby's Head Shape?
Our Skully Care app measures key points on your baby’s head from a photo you upload. It measures four specific lines to calculate both the CVAI and the CI.
The formulas of Loveday & De Chalain (1)
CVAI (%) = (a - b) / b × 100%
a = the longer line of line 1 or line 3
b = the shorter line of line 1 or line 3
CI (%) = length of line 4 (ear to ear) / length of line 2) × 100%
Line 2 starts at the nose, crosses the midpoint of line 4, and reaches the edge of the head (mCVAI).
The CVAI formula compares the difference between these two diagonals. If the CVAI is greater than 3.5%, this suggests that the baby has significant plagiocephaly. For example, if the measurement is 6.2%, as in the case of a baby with a slight head rotation preference to the left, it indicates mild plagiocephaly.
Interpreting the Results: Plagiocephaly Severity Scale
We are using the Plagiocephaly severity scale to classify the extent of plagiocephaly. It classifies the severity of cranial deformities into five levels, see below. Once you’ve received the results from Skully Care, it will show you how severe your baby’s head shape issue is.
Level: CVAI (%): Common clinical symptoms:
<3.5 — The head is not / barely tilted
3.5 to 6.25 — The head is slightly tilted
6.25 to 8.75 — The head is moderately tilted
8.75 to 11.0 — The head is clearly tilted
>11.0 — The head is very clearly tilted
Brachycephaly Severity Scale
Level: Description: CI (%):
The head has a normal width — <90
The head is slightly wider than normal — 90-95
The head is moderately to clearly too wide — 95-100
The head is (very) clearly too wide — >100
An example of a baby with a skull deformity
In the photo (Figure 1), the baby shows a clear preference for turning their head to the left. As a result, skull growth is restricted in the spot where the baby lies on the left side. Meanwhile, growth continues in other areas of the head, leading to a crooked shape. Despite this, the internal space of the head remains sufficient for brain development.
The diagonal measurement from the left back to the right front is shorter than the opposite diagonal from the right back to the left front. The CVAI measures this difference — in this case, it’s 6.2%, meaning that the longest diagonal is 6.2% longer than the shortest. This places the baby at level 2, which indicates mild plagiocephaly (Figure 2).
You might notice that the baby’s head appears round, but the ideal shape would be more elongated. This shape is influenced by genetic factors and cultural differences. The measurement from ear to ear in this baby is slightly shorter than the length from the nose to the back of the head. If these measurements were equal, the CI would be 100%, indicating a significant flattening. In this case, the baby’s CI is 94%, showing mild brachycephaly (flattening of the back of the head). Most researchers set the cut-off for brachycephaly at 90%.
Why early detection is key
Early detection of plagiocephaly is crucial because it can often be corrected more easily if caught early. With our Skully Care App, you can track your baby’s head shape right from the comfort of your home, understand the severity level and decide if further action is needed. It is also perfect to check the progress in between or to perform an additional follow-up measurement.
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