Understanding CVAI and CI Numbers for Infant Head Shape: A Guide to Positional Plagiocephaly

There has been a growing awareness regarding the development of head shape in infants, with one  condition in particular—plagiocephaly—gaining attention. Plagiocephaly is the asymmetrical flattening of  a baby’s skull, typically caused by pressure on one side of the head for extended periods of time. This  type of head flattening is becoming more common due to babies spending more time on their backs and with the increase in diagnosis of torticollis, or tight muscles. .  

To diagnose and track head flattening, providers utilize two important numbers—Cephalic Index (CI) and  Cephalic Volume Index (CVAI)— both playing a critical role in assessing head shape and guiding  treatment. These objective numbers offer a way for healthcare professionals to quantify the degree of  cranial deformities and monitor the effectiveness of interventions.  

In this blog post, we’ll explore how CVAI and CI numbers relate to infant head shape, how they can help  diagnose plagiocephaly, and why they are helpful in managing cranial conditions in babies. 

What is positional plagiocephaly? 

Plagiocephaly is a condition where one side of an infant’s head becomes flattened, leading to asymmetry  in the skull. It can result from external pressure on the skull, such as when a baby spends a significant  amount of time lying on their back, or in one position. The risk of plagiocephaly is also directly linked to the diagnosis of torticollis, or muscle tightness. This is most often noticed by parents/caregivers  between 2 to 4 months of age.  

The Role of the Cephalic Index (CI) in Infant Head Shape 

The Cephalic Index (CI) is a measurement that helps determine the proportion of an infant’s head width to  its length.  In the case of flat head syndrome, the CI can be a valuable diagnostic tool for categorizing the  severity of the condition. It’s a simple, non-invasive way to assess the shape of a baby’s head and track  any changes over time. 

The CI is calculated using this calculation: Max Width of Head / Max Length of Head * 100 

A child with flat head syndrome may exhibit an abnormally high or low CI, depending on the type and severity  of the skull deformation. A high CI could suggest a broad or flattened head, while a low CI could suggest  a more narrow or elongated head. 

The Role of the Cephalic Volume Index (CVAI) in Infant Head Shape 

While CI focuses on proportions, the Cephalic Volume Index (CVAI) takes a more comprehensive  approach by considering the overall volume and symmetry of an infant's skull to determine the extent of  deformities present, if any. 

The calculation for CVAI is more complex and can involve specialized imaging techniques like 3D cranial  scans or CT scans. These scans capture a more complete picture of the infant’s skull, measuring the  volume of the cranial cavity and identifying areas of flattening or abnormal growth through diagonals. This 

is especially useful for more severe cases of plagiocephaly or for identifying conditions that may require  surgical intervention. 

For babies with positional plagiocephaly, CVAI can help track how the skull is changing in volume over  time and assess the effectiveness of treatments. The higher the CVAI percentage, the more severe  plagiocephaly is classified. 

CI and CVAI in Diagnosing and Treating Plagiocephaly 

In practice, CI and CVAI are applied in the following ways: 

• Early Diagnosis: CI and CVAI can help pediatricians assess head shape during routine checkups.  Abnormal measurements can signal the need for further evaluation, with a recommended referral to a  physical or occupational therapist who is specialized in treating underlying causes of this condition. 

• Treatment Planning: If plagiocephaly is diagnosed, CI and CVAI can be used to determine the severity  of the condition and guide the treatment plan. They can guide parents and healthcare providers in  making decisions about whether physical or occupational therapy alone is sufficient, or if additional interventions such  as helmet therapy are needed 

• Monitoring Progress: Both CI and CVAI can track the baby’s head shape over time to see if the  treatment is working. Changes in these numbers can indicate whether the skull is returning to a more  normal shape. 

Conclusion 

The Cephalic Index (CI) and Cephalic Volume Index (CVAI) are valuable tools in assessing and managing  infant head shape, especially in the context of conditions like plagiocephaly. By using these  measurements, healthcare providers can track the development of an infant’s skull, diagnose potential  issues early on, and monitor the effectiveness of treatments. 

Early intervention by a physical or  occupational therapist that specializes in this area can help ensure that any cranial deformities are  properly addressed, supporting healthy growth and development for your baby. Did you know we can measure this during an appointment with Year One Wellness?

For more information, feel  free to reach out to us! Our team of clinicians are pediatric  physical/occupational therapists and certified breastfeeding specialists, and we are here to help! Year  One Wellness offers virtual consultation everywhere and in-person consultations in and around Austin,  TX.