“Normal” head shape can be seen in the figure to the left. This picture is only a guide, however – normal head shape includes a range of sizes and minor deviations from this idealized form.
Acquired cephalies, or types of flat head syndrome, are normally diagnosed using a set of skull measurements. Occasionally there are visible differences in the position of an ear or the appearance of the face as well.
Any diagnosis of cephalic deformation has to rule out the possibility of craniosytosis – a condition which results from the skull bones fusing together before the skull has finished growing. Craniosytosis requires surgery, so it is important if your baby’s head appears to be misshapen to see a doctor to determine the cause.
Degrees of severity
Mild cephalic deformities may go unnoticed by parents and doctors, or may be easily dismissed as a cosmetic problem. A baby who has a mild cephalic malformation will have a skull with only slight flattening or elongation. Diagnosis will require measurements of the skull to be taken.
An infant with a moderate cephalic malformation can be diagnosed by sight, although measurements should be taken to determine the extent of the condition. An infant with a severe cephalic deformity exhibits an extreme degree of flattening on one part of the skull. Measurements, x-rays and other diagnostic imaging tests may be performed to rule out craniosytosis.
Diagnosis and Abnormal Head Measurements
The presence of plagiocephaly, brachycephaly, and scaphocephaly is generally determined by abnormal skull measurements. Plagiocephaly, brachycephaly and scaphocephaly can be identified using a craniometer or a medical laser designed for the same basic purpose. A craniometer looks a lot like the protractors we all used in elementary school for drawing circles and measuring angles, and depends on subjective decisions by your baby’s practitioner. Lasers provide a more accurate and less subjective measurement, and their popularity is growing as a result.
When evaluating for plagiocephaly, craniometers and lasers are used to take two measurements of your baby’s skull, and the severity of plagiocephaly is determined by the difference in these measurements. The measurements are essentially like what you would see if you drew and X on the top of your baby’s head. Mild plagiocephaly has a difference of up to 9mm. Moderate plagiocephaly is determined by a 10-19mm difference, and severe plagiocephaly exhibits a 20mm or greater difference.
One of the most common measurements taken in the evaluation of brachycephaly and scaphocephaly is the cephalic ratio, or cephalic index, which is a rather fancy term for the measurement taken by dividing the size of the widest part of a baby’s skull by the longest part of the skull, in millimeters and multiplying by 100. There is no consensus as to what the ‘normal’ cephalic ratio of an infant should be, however.
In 1979, one of the first studies which tried to resolve the question of what a normal head shape is resulted in a 78-78.5% ratio, with gender being an important factor. Since that point, over 10 different ratios have been proposed as indicative of a significant brachycephalic cranial deformity, but most researchers and doctors propose a number in the low 90th percentile, ranging from 90-93% as a reliable marker for severe cranial deformities and a starting margin for clinical studies of cranial remolding therapies.
Scaphocephaly is generally considered to be a cephalic index measurement below 78%. There are many ‘normal’ head shapes, and your doctor may determine that your baby doesn’t necessarily have brachycephaly, scaphocephaly or plagiocephaly if their head mesaurements are close to the ‘normal’ point and either you or your partner comes from a family with head shapes that are similar to your infant’s.
For complete information on flat head syndrome in babies including how to tell normal from abnormal head shape, as well as how to prevent and treat these conditions, please see our ebook.