Many pediatricians still firmly adhere to the idea that deformational flattening resolves with growth and time. Unfortunately, this false concept induces a number of families to wait month after month in vain for the flattening to “pop out”. The reality is that once flattening is established at 6-8 months, it is there to stay. Critics of this notion will point to the many peer-reviewed papers that show improvements in measures such as the oblique cranial ratio (OCR; a measure of relative cranial asymmetry), subjective measurements, and less commonly, the transcranial difference (an absolute measure of asymmetry). For further discussion of each of these measurements, see https://www.thenoggindoctor.com/#the-science. Unfortunately, these methods of measuring asymmetry are fundamentally flawed in capturing what is most concerning to parents- will this be noticeable to other people and be a potential source of ridicule for my child? The OCR and subjective impression look better with growth because the flattening stops progressing after 4-5 months of age (once the baby gains enough motor control to begin rolling and getting off the flat spot) yet the head continues to enlarge. Thus, a fixed flattening on a larger head looks less pronounced. Improvements in these measurements can only be interpreted as relative, but not absolute, improvement in the asymmetry. Improvements in this ratio are only relevant if we are evaluating the head asymmetry from a vertex (top down) view, as we see infants and young children. In older children or adults, the back of the head is seen only from the side and back (unless one is a shoe salesperson!), therefore, the only measurement that matters from this perspective is the absolute asymmetry, or the difference between the projection of one side of the occiput and the other. There is little evidence to suggest that this measurement, the transcranial difference, improves dramatically with growth. The few studies that show some improvement of this measure over time are suspect because the anthropometric landmarks used to define the transcranial difference are imprecise, and can shift as head grows and changes shape. Fortunately, even a fixed asymmetry will appear less pronounced as the head grows larger and the visual perspective of the asymmetry changes from a vertex view (top down) as is the case in a young child or infant, to a posterior/side view as we see older children and adults. I will point out that the discussion so far is only for asymmetry and the evidence that brachycephaly, symmetrical or near symmetrical flattening, improves over time is less convincing. In contrast to asymmetrical head flattening, which we rarely see in adults, symmetrical head flatting (which presents and a broader head with a flat occiput) is quite common. In the years before COVID-19, I would still on airplanes and evaluate head shapes. You did not have to look far to see a number of adults in whom the back of their head is flat!

Given that most asymmetrical flattening looks less obvious with growth, should clinicians recommend that parents of children with even severe plagiocephaly merely wait until the child’s head and body grow sufficiently large to mitigate the effect? In my practice, I discuss this with the parents and let them decide. I have encountered a range of parental attitudes about head flattening ranging from “who cares” and “I am not sure why I was sent here” to parents literally sobbing with guilt about the way the infants head looks to them. I tell them three things: 1) there is no evidence that deformational flattening has any adverse medical or cognitive effects; 2) with growth, the flattening tends to look less pronounced; and 3) there is nothing you could have done to change this. Most patients who develop head flattening have a relative limitation of head motion early in life, almost always due to cervical stiffness or imbalance (torticollis), and repositioning gin this at-risk group is both futile and impractical. Repositioning is highly effective for the 85% of infants that do not have a condition that affects head mobility, and would never have gotten flat in the first place! Ater this discussion, I probe their tolerance for observing the asymmetry during the time it will take for “improvement”. In severe cases, this may take years; in milder cases, months. For parents who are not bothered by their child’s head shape, I reassure them that the shape will continue to look better with growth (“If you are satisfied with the shape now, you will be even more so over time.”). Parents who are very upset by the appearance of their child’s head are, in my experience, likely to continue focusing on this for years to come. For these families, I usually recommend a molding helmet if the flattening is moderate or severe. While there are many studies that show improvement with helmeting, and most of us who have worked in the area clinically concur, there are a few well-publicized, but methodologically-flawed, investigations that suggest helmets are ineffective. These studies are categorically wrong! For example, a celebrated study from the British Medical Journal, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006966/ showed that helmets did little more than other conservative measures to correct asymmetry. One of the issues with the study, which was widely criticized, was that it relied on a measurement called the oblique diameter difference index (ODDI), or the longest oblique/shortest oblique. The measurements were taken at 5 months and 24 months and as a matter of simple math, it is quite obvious that as the head grows, the percentage difference in this ratio improves even if the absolute difference is unchanged. For example, an absolute difference of 10 mm might yield an ODDI ratio of 120mm/110mm (1.09%) in a 5 month old, but an ODDI of 160mm/150mm (1.67%) the same, but much larger, infant at 24 month of age. Clearly the absolute difference is the same, but the use of a ratio to measure asymmetry and improvement artificially biases the results and makes the study and it’s conclusions fatally flawed.

There is little question that a well made, properly fitted, and consistently worn helmet orthosis absolutely will improve cranial shape far beyond what is seen with mere observation or physical therapy. Indeed, most flattening stops progressing by 4-5 months of age because the infants are more mobile and many are able to roll over. The good news is that the flattening will not progress. The bad news is that efforts like repositioning are totally ineffective for the same reason (i.e, the infant can move to their comfortable position). If spontaneous improvement were the rule, one would see dramatic improvements between ages 5-12 months, a period during which head growth exceeds what occurs in the subsequent two years from12-36 months. I cannot count the number of parents who, after months of patiently waiting for spontaneous improvement, show up with their 12-14 month old infant who still shows significant flattening in spite of trying multiple correction strategies (e.g., pillows, repositioning, PT, craniosacral therapy) have failed. For those who choose to place their infant in a helmet, the subsequent correction even at that late age is dramatic. Parents invariably report impressive gains in the first 1-2 months, gains that exceed what occurred over the preceding months of repositioning. Parents should know that helmets are still effective up to 18-20 months (as a rule, as long as there is head growth), but the rate of correction slows significantly, and older infants may be resistant to keeping the orthotic in place. See https://www.ncbi.nlm.nih.gov/pubmed/23271554.

The decision to helmet is best left up to parents, and the decision to prescribe a helmet should be based not only the degree of flattening and asymmetry (my cut-offs are >9 mm for asymmetry, CI (width/length ratio >0.9) but also on parental tolerance for and acceptance of the asymmetry. In my opinion, providers should never categorically deny parents access to helmet therapy based on some selective literature (“The study from…. says helmets don’t work”), personal aesthetic philosophy (“Its not that bad… just grow his hair longer.”) or some secondary financial motive (“Helmet therapy is a waste of health care resources.”). In the end, the parents must live with the decision, and it is their opinion that should be controlling.