Deformations (Positional Plagiocephaly)
There are two basic causes for an abnormal skull shape in an infant: craniosynostosis and skull deformations. Craniosynostosis involves a fusion of one of the sutures of the skull that restricts growth, and therefore needs to be treated with surgery. This condition is discussed elsewhere (see Craniosynostoses). However, the most common cause for an abnormal skull shapes comes from outside pressures on the skull that slowly mold a change in shape. These pressures are called “deformational.” After the Back To Sleep campaign was initiated by the American Academy of Pediatrics in 1992, with hopes of lowering the incidence of SIDS (Sudden Infant Death Syndrome), physicians noted that more and children were showing up with flat areas on the backs of their heads. Early on, many children with flat heads were incorrectly diagnosed as having craniosynostosis, and a number underwent unnecessary surgery.
What causes a deformation?
Deformations probably begin in the uterus (womb). Within this tight space, babies usually cannot keep their necks completely straight so with the head tilts to one side, which causes the neck muscles will develop slightly shorter on the side that is flexed. Depending upon how long and how flexed the neck is, a baby might develop what is called “torticollis.” More often, the neck muscles are only shortened a little bit and parents may notice that their child prefers to look to one side more than the other, or sleep with their head always turned to the same side. Over time, with a baby always looking the same way, the back of the head will get flatter from constant pressure of just lying on just this one side. Once a slight flat spot develops, the head is more likely to roll to that flat spot when the baby is on his or her back, and the condition slowly gets worse. This flatness may be first noticed by the pediatrician sometime around the two-month check up, but some families may have noted this earlier. It is typical that this flatness will get slightly worse by the four-month check up, and many pediatricians may consider a referral to a craniofacial surgeon, pediatric neurosurgeon, or directly to a headbanding center. However, once a child begins rolling over on their own at night (usually about 5 to 6-months of age), this flatness will not only stop getting worse, but will start to improve on its own.
How do I know if my child has a deformation and not craniosynostosis?
Although many centers routinely order plain x-rays or even CT scans, the diagnosis of positional plagiocephaly (or skull deformation) can be easily made by just doing a careful physical exam without ordering any studies. Children with deformations will usually have flattening on one side of the back of the skull, although both sides can be affected. Often the forehead, on the same side of the back flatness, is further forward and sometimes the cheekbone will also be more prominent on this side. When the back of the head is flat on one side, and on the same side the forehead is further forward, we refer to this as a parallelogram deformity. Sometimes this is more obvious when you lightly place your index fingers in each ear canal in order to see which side is further forward. It is a lot more common for the right side to be flat than the left, and this condition is also more common in twins. It is important to make sure that the flatness is coming from an outside pressure and not the result of craniosynostosis (specifically, a fused lambdoid suture). One of the key ways to tell which condition is causing the flatness is to look at the height of the skull on the flat side. With positional plagiocephaly, the skull height is normal but with craniosynostosis the skull height is reduced. Other signs of craniosynostosis are a low skull bulge behind the ear on the same side that is flat, and compensatory overgrowth of the opposite side, with the skull bulging off to the side (see the section on lambdoid synostosis). As a rule of thumb, if the height of the back of the skull on the flat side is the same as the other side, the child almost certainly has positional plagiocephaly.
Do deformations cause any internal problems?
Most craniofacial surgeons and pediatric neurosurgeons agree that deformations do not cause any problems with the brain or the child’s development. Although their have been studies suggesting that children with deformations (and who were treated with a helmet) might have a higher chance of having a behavioral problems later in life, this does not mean that the flatness cased these issues. In fact, most doctors believe that positional plagiocephaly does not cause any problems with the brain, eyesight, hearing or jaw joints. At our center in Dallas, we believe that children who only have deformations are completely normal.
Do deformations need to be treated?
There are basically three possible treatment options: 1. Do nothing, 2. Try to keep a child off the flat side of the head by repositioning, and 3. Using a headband or helmet. We believe that the only reason to consider treating a child with a deformation is to improve the skull shape. There are no good studies that have shown that positional plagiocephaly causes any harm; therefore, parents must ask themseleves the question: if this condition does not get better would my child be teased about this flatness? As it turns out, there are a number of good studies that show that deformations get better on their own, just by doing nothing. In general, the best studies are called prospective randomized studies and there are at least two that show very little if any benefit to putting a child in a headband or helmet. It has been shown that childrens’ skull shapes do improve by using headbands, but newer studies also show that these areas of skull flatness will also get better on their own without doing anything. The way that headbands work is by preventing the skull from enlarging in most directions, forcing the growing brain to push out the skull in the area that is flat. At our center in Dallas, we have concerns about restricting skull growth, and based on those studies showing no benefits to using helmets, we now almost never recommend using these constricting devices in any children.
Jeffrey Fearon, MD
Director, The Craniofacial Center
Dallas, Texas U.S.A.