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ELECTRONIC ARTICLE |
* Division of Plastic Surgery
Department of Medicine at Children’s Hospital
Department of Psychiatry, Harvard Medical School, Boston, Massachusetts
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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Design. A cross-sectional study was performed in healthy newborns. Physical findings, anthropometric cranial measurements, and data on pregnancy and birth were recorded.
Results. The incidence of localized cranial flattening in singletons was 13%; other anomalous head shapes were found in 11% of single-born neonates. In twins, localized flat areas were much more frequent with an incidence of 56%. The following risk factors for cranial deformation were identified: assisted vaginal delivery, prolonged labor, unusual birth position, primiparity, and male gender.
Conclusion. We propose that localized lateral or occipital cranial flattening at birth is a precursor to posterior deformational plagiocephaly. The infant lies supine, with the head turned to the flattened area, and is unable to roll. Intrauterine risk factors for localized cranial flattening are the same as for deformational plagiocephaly. To avoid postnatal progression from a localized cranial flattening to posterior-lateral deformational plagiocephaly, we suggest amending the recommendation of the American Academy of Pediatrics on sleep position: Alternate the head position and allow sleeping on the side and, when awake, supervise prone time.
Key Words: cranial asymmetry • deformational plagiocephaly • newborn infant • sleep position
Abbreviations: SIDS, sudden infant death syndrome • TCD, transcranial difference
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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Plagiocephaly is either preponderantly anterior or posterior, or both. Before 1992, most American infants were placed prone, and anterior deformational plagiocephaly was commonly seen in our craniofacial unit. Physical findings easily differentiate this type of flattened forehead from synostotic frontal plagiocephaly, caused by unilateral coronal synostosis.7
In 1992, the American Academy of Pediatrics recommended that infants be placed supine to sleep to reduce the risk of sudden infant death syndrome (SIDS).8 This campaign has been successful with a decline in the prevalence of prone sleep position from 70% in 1992 to 24% in 19969 and coincident with lowered incidence of SIDS.9 Since this change in the sleeping position, our craniofacial unit and many other centers have documented a remarkable decrease in anterior deformational plagiocephaly; however, posterior deformational plagiocephaly has assumed almost "epidemic" proportions. Thus, it is generally accepted that this increase in posterior deformational plagiocephaly is related to supine sleeping.5,10–13 This phenomenon is also supported by the common observation of "flat heads" in Asian infants who are traditionally positioned supine. In countries in which infants lie traditionally on their back, the incidence of SIDS is low.14–19
There are subtle differences that discriminate between posterior (occipital) plagiocephaly caused by rare lambdoidal synostosis versus common deformational or positional molding. Plain radiographs of an infant with posterior cranial flattening were often interpreted as "functional synostosis" or "sticky lambdoid," although the suture was open. Many of these children with deformational posterior plagiocephaly underwent surgical correction.20–23 More recently, the physical findings that differentiate deformational and synostotic posterior plagiocephaly have been determined.5,24 At the same time, radiologists began reinterpreting plain films and using computed tomography to determine the correct diagnosis.25–27 Furthermore, clinical studies showed that deformational plagiocephaly could be corrected by positioning in the crib and use of a molding helmet.3–5 In fact, the incidence of true lambdoid synostosis is very rare (<4% of craniosynostosis).5,28
Usually, the parents and the pediatricians first notice deformational posterior plagiocephaly around 2 to 3 months. Mothers typically say that the infant’s head was round at birth. Thus, some investigators use the term "positional" plagiocephaly to underscore that the cranial flattening is postnatal, caused by sleeping in the "position of comfort."2
Other observers think that deformational plagiocephaly begins prenatally. They note the association with intrauterine constraint, resulting from a large fetus, a small or malformed uterus, increased abdominal muscular tone, or decreased amniotic fluid.29 Deformational plagiocephaly is also known to occur more frequently in multiple-birth infants.30 Bruneteau and Mulliken7 proposed that the fetal head becomes distorted in a parallelogrammic shape as the anterior cranium is compressed by the maternal pubic bone and the posterior cranium by the lumbosacral spine. This would account for the high incidence of right posterior and left anterior deformational plagiocephaly, as would be expected with the common left occipital anterior passage through the birth canal.
Nevertheless, the question of whether deformational plagiocephaly begins in utero is unanswered. The aim of our study was to determine whether early signs of cranial flattening could be detected in the newborn nursery. We documented the following: 1) the incidence of cranial flattening in healthy neonates, and 2) potential risk factors. Our working hypothesis was that if subtle posterior cranial asymmetry is present at birth, it may go unnoticed in the neonatal period. Then, as the infant lies on the flattened area, in the "position of comfort," the cranium progressively distorts. If this scenario occurs and infants with localized areas of cranial flattening could be identified at birth, then progression to deformational plagiocephaly could be prevented by early crib positioning.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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Physical examination of the neonate noted cranial or facial asymmetry, head shape, cephalohematoma, torticollis, and anomalies of the ears, the hands, the feet, and the hips. Height was measured in the crib, using a measuring board, for most infants; however, in some infants, such as those recently circumcised, height and hip stability were recorded from the charts.
Anthropometric cranial measurements were made, using a spreading caliper (Tyrostom Company, Olomouc, Czech Republic), with the head held in a neutral position by an assistant or the mother. Two oblique cranial diameters were determined, measuring from the supraorbital point (os, orbitale superius) to the parietooccipital scalp at the point of maximal convexity, as described previously.5 These diameters were measured 3 times, the average was recorded in centimeters and used to calculate the transcranial difference (TCD). Measurements of the head circumference were performed 3 times using a measuring tape; the average was noted in centimeters. All measurements were made by the same person with the same measuring device.
If an infant had either localized head flattening or cranial asymmetry, defined as a TCD of >4 mm, the parents were encouraged to change the infant’s position in the crib frequently and to position the infant away from the flattened area. Parents were also offered the opportunity to have their infant’s head shape reevaluated after 2 or 3 months in our craniofacial unit. The parents were given the transverse cranial diameters to allow comparison of the initial and the 2-month follow-up measurements without identifying the child in the primary study.
Data were tested for statistical significance with Pearson 
2 tests or with 1-way analysis of variance.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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Single-Born Infants
Of the 183 single-born infants, 24 (13.1%) were found to have lateral or posterior cranial flattening, and 21 (11.5%) had otherwise unusual head shapes on physical examination. Based on these findings, we divided the single-born neonates into 3 groups: 1) infants with a flat cranial area; 2) infants with otherwise unusual head shapes; and 3) neonates with normal head shapes.
Head Shapes
Of the 24 infants with flat areas, 9 were right posterior, 4 right lateral, 9 left posterior, 1 left lateral, and 1 bilateral posterior flattening. Thus, right-sided head flattening accounted for 54.2% of the total of the flattened areas. In most infants, the flat area was well localized, between 5- and 7-cm diameter. Six neonates with head flattening had anterior displacement of the ipsilateral ear (Fig 1).
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Anthropometric Measurements
The mean TCD was calculated and compared among the 3 groups. In the group of infants whose head shapes were unusual, but not flat, a cephalohematoma interfered with the posterior measuring point in 4 out of 11 cases, with TCDs ranging from 5 to 10 mm (attributable to the cephalohematoma). These 4 infants were excluded from the calculation of the mean TCD. Infants with head flattening had a mean TCD of 3.96 mm. When infants with posterior flattening were evaluated separately from those with lateral flattening, the mean TCD of infants with occipital flat areas was 4.74 mm, with a minimum of 0 mm, because of the case of bilateral posterior flattening, and a maximum of 8 mm. In neonates with lateral flattening, the mean TCD was 1 .0 mm, with a range from 0 mm to 2 mm. In contrast, neonates with otherwise unusual head shapes had a mean TCD of 1.29 mm, with a minimal value of 0 mm and a maximal value of 2 mm. Infants whose head shape was classified as normal had a mean TCD of 0.88 mm, ranging from 0 mm to 4 mm. Comparing the 3 groups with 1-way analysis of variance, the differences in the TCDs were significant (P < .001; Table 1).
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Primipara Versus Multipara
The primipara percentage was 62.5% in mothers of children with a flat area and 57.1% in mothers of infants with otherwise unusual head shapes, but only 37.0% mothers of children with normal heads. The differences in parity between these 3 groups were statistically significant (P = .02; Table 2).
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2 test, the differences in the modes of delivery were statistically significant (P < .001; Table 2).
Length of Labor
Information about the length of first-stage labor, corresponding to the period of regular contractions, and second stage labor, corresponding to active pushing, was obtained from the mothers. Average time for both stages was calculated for the 3 groups. Mothers with scheduled cesarean sections were excluded from both calculations, and mothers who underwent secondary cesarean section were excluded from calculation of the second-stage labor. A longer period of contraction and of pushing was noted for either infants with head flattening or other unusual head shapes, as compared with infants with a normal head shape. The mean time for first stage labor were 17.6 hours in the group of infants with a flat area and 16.1 hours in children with otherwise unusual head shape, as compared with only 10.8 hours in infants with normal head shape. Similarly, the times for second stage labor were as follows: 85 minutes for infants with a flat area and 76 minutes for those with other unusual head shapes, but only 45 minutes for neonates with normal head shape. Both were significant, with P = .002 for first-stage and P = .02 for second-stage labor (Table 3).
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Unusual Birth Positions
We noted positions other than the most common occipital anterior. Unusual birth positions were found in the 183 single-born infants: occipital posterior (n = 15); occipital transverse (n = 6); complete and incomplete breech (n = 4); compound head and hand presentation (n = 3); hand/arm/shoulder presentation (n = 1); and mentum anterior (n = 1). Among the 3 groups, unusual birth positions were distributed as follows: The percentage of birth positions other than occipital anterior was 29.2% in infants with a flat area, 19.0% in neonates with other unusual head shapes, and 13.8% in those with normal head shape. Thus, an unusual birth position occurred more frequently in infants with head flattening, as compared with the other groups. Analysis with the Pearson 2 test showed that when the infants with head flattening were compared with all other neonates, the difference was close to significance (P = .07; Table 4).
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Other Potential Risk Factors: Torticollis, Cephalohematoma, Oligohydramnios, and Anomalies of Uterus or Birth Canal
Because torticollis is known to be associated with deformational plagiocephaly, we expected to observe torticollis in the neonates with unilateral head flattening. However, torticollis was noted in only 2 infants with a flat area. One infant had right lateral head flattening and obvious ipsilateral torticollis, in combination with multiple other anomalies, including a flexion deformity of the left wrist, a left facial nerve palsy, and a left clavicular fracture. The other infant had right posterior head flattening and minor ipsilateral torticollis.
Of the 24 infants with flat areas, 6 (25%) presented with cephalohematoma. In all of these, the cephalohematoma did not extend over the whole occiput, but was limited to the vertex or the upper occiput, presumably the leading part during birth. Thus, it did not interfere with our transcranial measurements. The prevalence of cephalohematoma in all other neonates, however, was only 6.9% (n = 11), suggesting that cranial flattening is associated with cephalohematoma.
A priori reasoning suggests that deformational plagiocephaly might correlate with oligohydramnios. Among the 183 single-born infants, decreased or increased levels of amniotic fluid were recorded in 8 cases; 5 of these (3 oligohydramnios, 2 polyhydramnios) in the category of infants with normal head shape. Unexpectedly, we found 2 cases of polyhydramnios, but only 1 case of oligohydramnios in infants with cranial flattening. Our numbers are too small to draw conclusions from this observation.
The percentage of uterine or birth canal anomalies was 16.7% in mothers whose infants had head flattening, 14.3% in mothers of infants with otherwise unusual head shapes, and 8.0% in those whose infant had a normal head shape, suggesting an association of intrauterine constraint with cranial deformation. However, definitive correlation would require a larger number of cases.
Other types of anomalies (n = 28) were found: 22 in neonates with a normal head and 3 each in infants with head flattening and otherwise unusual head shapes. The most frequently noted were shoulder dystocia (n = 5), heart murmurs(n = 4), hydronephrosis (n = 4), hip dysplasia (n = 2), and club feet (n = 2). We did not find a correlation with head flattening and other unusual head shapes.
Twins
We examined 9 pairs of twins, all were dizygotic and diamniotic, with a male versus female ratio of 8:10. Three pairs were delivered vaginally, 6 by cesarean section. Six mothers were primipara.
The prevalence of head flattening in twins was 55.6% (n = 10), more than 4 times as frequent as in singletons. Of these 10 infants, 5 presented with a right posterior, 2 with a right lateral and 3 with a left posterior flat area. Thus, preponderant right-sided flattening was noted. These flat areas were well-localized, and in 2 infants the ipsilateral ear was forward. In twins, the TCD of 3 mm was more easily perceived, compared with single-born infants with a flat area. Although most single-born infants with a TCD of 3 mm had normal head shapes, on physical examination, the same TCD of 3 mm was often perceived as a flat area in twins. A possible explanation for this observation could be that multiple-birth infants generally have smaller heads; thus, a smaller degree of asymmetry is more noticeable. The mean TCD in multiple-birth infants with head flattening was 3.40 mm, compared with a mean TCD of 3.96 mm in the group of single-born neonates with a flat area.
In the 10 twins with a flat area, the gender ratio was 1:1. Three were born by normal vaginal delivery, 7 by cesarean section; 6 were delivered as firstborn. Thus, gender, mode of delivery, and parity were similarly distributed as in the population of examined twins. A flat area was found in first-born twins (n = 6) and in the second-borns (n = 4), and in twins with vertex presentation (n = 7) and breech presentation (n = 3). Associated deformational anomalies were observed in 4 twins with a flat area: Two of these presented with clubfeet—1 with a small jaw and 1 with an auricular deformation.
Otherwise unusual head shapes were noticed in 3 multiple-birth infants, including cephalohematoma, dolicocephaly, and frontal bossing (n = 1).
When all 18 twins were compared with all singletons, twins were found to have a higher TCD: 2.33 mm in twins versus 1.33 mm in singletons. This difference was statistically significant (P < .01; Table 5).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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We emphasize that a well-localized flat area we observed in our study does not constitute fully developed "neonatal plagiocephaly." However, we suggest that many of these infants with posterior or lateral flattening will likely develop posterior deformational plagiocephaly. In the past, when infants were positioned prone, this common posterior flattening improved spontaneously. The infant with congenital posterior flattening lying supine will prefer to turn the head to the flat side because this position is most comfortable. Thus, congenital occipitoparietal deformation is perpetuated and accentuated by pressure from the mattress. Assuming this pathogenesis, the term "positional" rather than "deformational" plagiocephaly has some merit, although the precursor to deformation is present at birth. As this flattening is quite subtle, it is frequently overlooked in the neonatal period. This explains why most mothers of infants with deformational plagiocephaly recall that their infant had a normal head shape after birth,36 and why parents and pediatricians often do not notice deformational plagiocephaly until 2 to 3 months of age.5
This study showed a prevalence of 13% of localized cranial flattening in essentially healthy newborn singletons. The incidence of fully developed posterior deformational plagiocephaly in infancy is not known, as there have been no good prospective studies.40 Data from the 1970s suggest an incidence of 1:300 for occipital plagiocephaly.41 Given the almost epidemic increase in the problem reported by many craniofacial centers since the 1992 recommendation of the American Academy of Pediatrics, the present incidence is likely much higher. Furthermore, without a prospective study, we cannot predict how many neonates with localized flat areas will develop full deformational plagiocephaly. Nor can we know whether the 13% of newborns with congenital flat areas account for all of the increased incidence. The reasons that we did not do this study are: 1) this would require funding to follow 200 healthy infants; 2) and, more importantly, we had alerted the parents to the cranial flattening and had given instruction to keep the infant’s head off the flat area. Therefore, such a study would be scientifically flawed.
Neonates with a gestational age of <36 weeks and neonates who required prolonged intensive care treatment during their first days of life where excluded from our study. Preterm infants, low birth weight infants and seriously compromised neonates, are, however, more likely to have anomalous head shapes than essentially healthy newborns.42 All pediatricians and neonatologists are familiar with the dolicocephalic head so commonly observed in preterm infants; often called "preemie head." Preterm infants have malleable calvarial bones,43–46 making them more susceptible to molding forces during birth. In addition, newborns who receive prolonged treatment in the intensive care unit have a higher incidence of neurologic impairment, which is another risk factor for deformational cranial anomalies.47 Thus, we assume that the true incidence of cranial flattening in all newborn singletons is slightly higher than in the population assessed in this study.
All examined newborns were classified as having either cranial flattening, infants with an unusual head shape, or normal head shape, according to our physical examination. Because the measurements were recorded within 24 to 72 hours of life, it could be argued that the localized flattening we found is a transient phenomenon. However, in our experience, cranial molding improves within hours of birth and resolves within days. Hence, our finding of localized flattening on the second and third days of life is unlikely to be evanescent.
When the anthropometric measurements for these 3 groups were compared, there was, all in all, a very good correlation between transcranial measurements and physical findings. The mean TCD in infants with a normal head shape was <1 mm and a TCD of 4 mm was, in general, perceived as a posterior flat area. However, a few infants with TCDs of 4 mm had a perfectly normal head shape on physical examination. This is a general problem of anthropometry: the measured difference does not always correlate with the perceived degree of asymmetry.
The few infants whose heads looked completely symmetrical but with a measured TCD of 4 mm should be carefully monitored. However, decisions about treatment should be made according to the perceivable degree of asymmetry, and not based solely on anthropometry.
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CONCLUSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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These are simple instructions that we consider effective to avoid progression from a localized flattened cranial area to posterior-lateral deformational plagiocephaly. We believe that if both parents and pediatricians paid more attention to the infant’s head shape and crib positioning, the high incidence in posterior deformational plagiocephaly would decrease significantly.
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FOOTNOTES |
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Reprint requests to (C.H.K.) Department of Pediatrics, Children’s Hospital, 300 Longwood Ave, Boston, MA 02115. E-mail: connie.keefer{at}tch.harvard.edu
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONREFERENCES |
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This article has been cited by other articles:
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  E. A. Fowler, D. B. Becker, T. K. Pilgram, M. Noetzel, J. Epstein, and A. A. Kane Neurologic Findings in Infants With Deformational Plagiocephaly J Child Neurol, July 1, 2008; 23(7): 742 - 747. [Abstract] [PDF]
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 V. Wall and R. Glass Mandibular asymmetry and breastfeeding problems: experience from 11 cases. J Hum Lact, August 1, 2006; 22(3): 328 - 334. [Abstract] [PDF]
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 R. G. Elluru Adenoid Facies and Nasal Airway Obstruction: Cause and Effect? Arch Otolaryngol Head Neck Surg, October 1, 2005; 131(10): 919 - 920. [Full Text] [PDF]
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