Features of the Head As Seen in Down Syndrome
There are certain features of the head that are seen in people that have Down Syndrome. These features vary in people with Down Syndrome. Some people with Down Syndrome will have all of these features and some will have a few of these features.
Having these features does not mean that someone has Down Syndrome. These features can be present in other medical conditions that are not related to Down Syndrome.
However, if a medical professional sees these features in combination, they may suspect a diagnosis of Down Syndrome.
The objective of this series is to bring awareness that many of the features seen in Down Syndrome, are also seen in individuals without Down Syndrome. These features on their own or as a whole do not define individuals who have them, irrespective of whether you have Down Syndrome or not. What makes these features significant is that they are different from the general population, that’s all. How individuals are treated with these features are more of a perspective problem of society than an individual problem.
Where there are features that are specific to Down Syndrome and/or affect the individual on a medical level, I will identify them as they are presented in this series.
Listed below are physical features of Down Syndrome related to the head. A reminder that although these are all features of Down Syndrome, not all people with Down Syndrome will have all of these features.
Features of the head related to a Down Syndrome diagnosis:
- separated sagittal suture (common finding)
- skull rounded and small
- flat occiput
- enlarged anterior fontanel
- sparse hair (variable)
It can be overwhelming to try and decipher what these characteristics mean for someone with Down Syndrome. In order to understand it, we need to learn a little more about the anatomy of the newborn head.
Figure 1 (Left) Lateral view of the newborn skull. (Right) Superior view of the newborn skull. From “The Abnormal Fontanel”, by Kiesler, J. & Ricer, R. , 2003, American Family Physician, 67(12), p. 2547. Retrieved October 10, 2017 from http://www.aafp.org/afp/2003/0615/p2547.pdf
Brachycephaly in Down Syndrome As It Relates To Positional Plagiocephaly (Flat Head Syndrome)
Fontanels and Sutures Seen In Down Syndrome
Fontanels are gaps in where the bones meet. These gaps are covered by fibrous connective tissue. 96% of all the fontanels close by the 2nd year of life and all will have closed by age 5 (Beasley, M. (n.d.). Age of fontanelles/cranial closure. Center for Academic Research and Training in Anthropogeny. Retrieved October 12, 2017 from, https://carta.anthropogeny.org/moca/topics/age-fontanelles-cranial-sutures-closure).
The purpose of fontanels is to provide enough area so that the newborn skull may be molded (bones overlapped and compressed during the childbirth process of a vaginal delivery) during birth. All newborns including those with Down Syndrome, have 6 fontanels. Baby’s have two fontanels that are top of of their head. One in the front called the anterior fontanel and one in the back called the posterior fontanel. The posterior fontanel closes by two months of age however, the anterior fontanel remains open for longer, often closing by two years of age. The size of the anterior fontanel is not associated with the timing of closure and will close sooner in boys than in girls (Kiesler, J. & Ricer, R. (2003). The abnormal fontanel. American Family Physician, 67(12), p. 2547. Retreived October 10, 2017 from http://www.aafp.org/2003/afp/0615/p2547.pdf).
In individuals with Down Syndrome, closure of the anterior fontanel is delayed (Kiesler & Ricer, 2003) and the fontanel is enlarged (Potter, P.A., Perry, A.G., Ross-Kerr, J.C., & Wood, M.J. (2006). Canadian fundamentals of Nursing (3rd ed.). Toronto, ON: Elsevier Canada. p. 1043).
Sometimes, there is a third fontanel seen between the anterior and posterior and this fontanel is associated with hypothyroidism and Down Syndrome (Kiesler & Ricer, 2003).
Children with Down Syndrome will not have a bulging or sunken fontanel. Their fontanels will be normal and in line with the shape of their head. A bulging fontanel is a sign of intracranial pressure and is a medical emergency. A sunken fontanel is a common sign of dehydration and is a medical emergency. If your child has a bulging fontanel or sunken fontanel or you are unsure, please have your child seen immediately by a medical doctor.
A newborn’s head comprises of different shaped bones that make up the skull. There are parts on the skull where the bones meet together and these are called sutures. These sutures are “sutured” or held together by fibrous connective tissue. As the brain and head grows, the fibrous connective tissue expands and is slowly osseified with bone. These sutures close later in adulthood. These sutures have been noted to close as early as 20 years of age to as old as 50 years of age, according to post-mortem studies (Kumar, V., Agarwal, S.S., Bastia, B.K. MG, S., & Honnungar, R. (2012). Fusion of skull vault sutures in relation to age-A cross sectional
postmortem study done in 3rd, 4th & 5th decades of life. Journal of Forensic Research, 3(10). DOI: 10.4172/2157-7145.1000173).
In individuals with Down Syndrome, the sagittal suture may be separted and is a common finding in those with Down Syndrome (Potter et al., 2006). Sagittal suture and anterior fontanel enlargement and closure delay, may contribute to positional plagiocephaly, leading to a more pronounced brachycephaly in Down Syndrome.
Another suture, the coronal suture, in Down Syndrome may close prematurely which is responsible for the physical skull structure of permanent brachycephaly.
Positional Plagiocephaly: Brachycephalpy in Down Syndrome
As discussed above, the fontanels and sutures may be enlarged and have a delay in closing when an individual has Down Syndrome. When there is a delay in closure, it means that the skull is able to mold, move, and take shape over a longer period of time.
All infants irrespective if they have Down Syndrome or not, run the risk of having a flattened head if they are sleeping on their back every night and remain on their backs during daytime play. The difference is that in Down Syndrome, the sutures and fontanel closures are delayed, meaning that children with Down Syndrome spend more time in this period of development than others. Consequently, this puts children with Down Syndrome at a greater risk for positional plagiocephaly (flat head syndrome caused by remaining in a position for longer than desirable).
Flat Head Syndrome as a whole is commonly referred to as plagiocephaly. Brachycephaly describes the flattened shape at the back of the head and is only one type of “flat head syndrome”. (The back of the head is referred to as an occiput, hence “flat occiput” seen in Down Syndrome). There are three types of flattended head: plagiocephaly, brachycepaly, and scaphocepaly. Often, flat head syndrome is a result of a positional issue than an issue of the skull fusing early. In Down Syndrome, it can be a positional issue.
“Flat Head Syndrome” pictures from Cranial Technologies. (n.d.). At-Home assessment. Retreived October 12, 2017 from, http://www.cranialtech.com/online-assessment
Plagiocepaly in Down Syndrome may not be a fixed condition and the head shape can be molded to normal. This is why tummytime during play is important for infants. Do not place your infant to sleep in any position other than their back. Not placing your infant on their back during sleep puts your infant at risk for Sudden Infant Death Syndrome (SIDS).
Other ways to encourage reshaping the head to normal on its own is to hold your baby. Whether it is putting baby in a carrier to run errands, do housework, or go for a walk; the longer baby is in a held positon or a position where you are moving them around while awake or asleep, they will not stay in any one position long enough for flat head syndrome to occur. Another way you can try is to breastfeed your baby. When baby breastfeeds, it is natural for the mother to reposition baby and herself throughout the feed as the feed progresses. Giving your baby skin-to-skin or “kangeroo hold” is a great way to hold baby and prevent plagiocephaly. How often do you move baby? To encourage a change in blood flow, most people move about every 20 minutes or so when they are sleeping and more often when they are awake. The idea is to keep baby more active while awake than asleep.
DO NOT IN ANY CIRCUMSTANCE SHAPE YOUR BABY’S HEAD ON YOUR OWN. SEVERE DAMAGE CAN OCCUR AND ANY DEVICES APPLIED TO THE HEAD, INCLUDING YOUR OWN HANDS, IS ADVISED AGAINST. PLEASE SEE YOUR BABY’S DOCTOR IF YOU ARE CONCERNED ABOUT PLAGIOCEPHALY.
Brachycephaly In Down Syndrome As It Relates To Crainofacial Abnormalities
The rounded and small structure of the skull in Down Syndrome has no direct impact where it affects the brain. There exist other medical conditions where the skull is small and Down Syndrome is one of them. Instead, it refers to the common finding that the brain itself in those with Down Syndrome are relatively small compared to those without Down Syndrome.
The skull functions as a typical skull would do, protecting the brain from injury. The brain functions as a typical brain would do, being responsible for the basic physical and mental functionings of the body. The difference lies in that there are subtle differences in skull structure, one of them being brachycephaly.
Figure 3 Morphometrical characteristics of Down syndrome (DS) skull and brain. A: lateral views of euploid and DS skulls. Left: the face of an euploid young adult presents downward growth of the maxillae; therefore, the distance between the inferior orbital ridge, the nasal spine, and the alveolar crest is considerably increased. The mandible is angled. Right: although the DS skull grows to nearly the same size as the normal adult, it presents brachycephaly, which means “short headed,” and occurs when the right and left coronal sutures close prematurely. Brachycephaly results in an abnormally broad head with a high forehead. It is often associated with other craniofacial abnormalities. In DS, the face is small, with underdeveloped maxillae, and the mandible is still relatively straight. (Redrawn from Benda CE. Down’s Syndrome: Mongolism and Its Management. New York: Grune & Stratton, 1960.) Figure from Dierssen, M., Herault, Y., & Estivill, X. (2009). Aneuploidy: From a physiological mechanism of variance to Down Syndrome. Physiological Reviews, 89(3), p.887-920. DOI: 10.1152/physrev.00032.2007.
When the coronal sutures of the skull close earlier than they should, it can create a brachycephalic look where the head is broad and the forehead is high. From my research, there appears to be no direct effect of the skull presenting as brachycephalic. What it does suggest is that since the skull is small, the brain is small as well; and in imaging studies, this is the case. That means, the constricted size of the skull has no effect on preventing the brain from developing and is not a result of the cognition ability seen in Down Syndrome.
There are many different kinds of mental delays from syndrome to syndrome, but not all mental delays are similar. They may be similiar in how one learns, for example, but structurally, the brain physically looks different (Dierssen et al., 2009). The brain structure is small in Down Syndrome and with brachycephaly present, the frontal and temporal lobes and cerebeller regions of the brain seem to be smaller in those respective areas. Whether the frontal and temporal lobes and cerebeller regions are smaller because of the shape of the skull or because the brain with Down Syndrome is small itself, is unclear. What is clear is, the neuronal networks and size of the brain is different and may be responsible for the function and cognition abilities we see in those with Down Syndrome; though it is unknown to what extent this may be (Ibid, 2009). To discuss this would be quite lengthy, if you wish to learn more, please follow the link: http://physrev.physiology.org/content/89/3/887
Sparce Hair As Seen In Individuals With Down Syndrome
Some individuals with Down Syndrome may have sparce or bald patches of hair with distinct borders. It is an autoimmune process that happens to 5-9% of the population with Down Syndrome (Leshin, L. (2001). Dermatologic disorders in Down Syndrome. Down Syndrome: Health Issues. [website]. Retrieved October 12, 2017 from, http://www.ds-health.com/derm.htm)
The autoimmune process desribed is called alopecia areata and is not due to infection or drugs. Otherwise, most individuals with Down Syndrome have hair just like the general population.
One interesting characteristic of Down Syndrome that I have been unable to find the explanation for is that the hair of individuals with Down Syndrome largely tends to be straight. Some sources say another characteristic is that the hair is thin as well. A possible explanation is that the gene for hair or something similar may present itself as overexpressed in the genome. Whichever the case, the hair of individuals with Down Syndrome is quite lovely from individual to individual.
As one can see, the characteristics of Down Syndrome vary. The more we learn about differences and ways to include others in society, the more acceptance we will have for those that are different from ourselves.
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