History

Throughout history, there has been evidence of intentional cultural head molding. People of ancient cultures have modified the shape of their infants’ heads using head wraps or positional devices to achieve a shape that was preferable to them. Ancient Egyptians used head binding to produce a cosmetically pleasing and fashionable elongation of skull shape. Deformation of the skull by pressure to an infant’s head dates back to 2000 BC. Reviews of the medical and anthropologic literature and examinations of anthropologic collections have found evidence of cranial deformation. Conclusions drawn by these reviews indicate that there does not appear to be any evidence of negative effect on the societies that have practiced even very severe forms of intentional cranial deformation (e.g., the Olmec and Maya). Some contemporary civilizations have practiced various forms of intentional and unintentional cranial deformation as well as prehistoric ones.^5,6

The same occurrence of unintentional head shape deformity that faces infants today has been present for ages, although we believe that interventions for SIDS may be increasing today’s incidence over that of previous times. Recent publications indicate that the incidence of plagiocephaly seen by pediatric neurosurgeons has greatly increased since the late 1980s and has been directly related to sleep position recommendations for infants to prevent SIDS. During the time that prevalence of occipital plagiocephaly was increasing, there was clearly controversy over the pathogenesis of the misshapen occiput. The disorder was thought to be secondary to lambdoid suture synostosis, partial fusions, or even “sticky sutures.”⁷ Lambdoid suture abnormalities do play a role in causing synostotic plagiocephaly, but they a rare.⁸ Many infants with nonsynostotic plagiocephaly may have been managed with surgical reconstruction, especially during the time period when identifying that most children with plagiocephaly were not harboring lambdoid synostosis.^9,10 As it became clear that the asymmetry was largely due to positional, gravitational forces, attempts were made to treat the deformation with external orthotic devices and avoid surgery unless clearcut evidence was found for synostosis. Surgery was reserved for those who failed conservative interventions. Many external cranial orthotic devices were devised. As these devices became more expensive and their results appeared to be incomplete in restoring normal head shape, other interventions were devised, including infant repositioning, physical therapy, and treatment of torticollis. Devices to aid the repositioning of the infant and other investigational techniques have been used. Controversy exists over the optimal treatment because reproducible, consistent success has not been found with any treatment as yet.

Scope and Impact

The scope and impact of this problem of plagiocephaly for today’s infants are extensive. The fact that plagiocephaly is occurring more frequently in today’s children is evident by the fact that the entity has been infrequently reported in journals and is absent from most medical texts from 25 years ago. Few infants received treatment before the late 1970s.¹⁰ Great concerns arise for parents of infants with significant head shape deformity. Many health care dollars are spent annually attempting to correct the asymmetry. Multiple physician visits are made, imaging studies obtained, expensive orthotic devices applied, and physical therapies instituted, and these interventions, along with occasional litigation of treatment failures, have multiplied the costs of what appears to be a benign disorder. Developers of proprietary devices compete for a portion of health care dollars spent in attempts to correct this deformity. Some children undergo surgical procedures similar to those used for craniosynostosis with the accompanying risks and morbidity. Research studies and publications have indicated that there may also be health concerns secondary to plagiocephaly occurring in the form of developmental delay and ocular, auditory, and mandibular pathology.^11–14

Incidence

Estimates indicate that 1 of every 60 neonates may have some degree of plagiocephaly or brachycephaly today.^15,16 The incidence of plagiocephaly in children has increased dramatically since the early 1990s and has been correlated with the practice of maintaining infants in the supine position.^4,16 Plagiocephaly is common among otherwise normal patients whose parents are unaware of their condition.¹⁰ The incidence of plagiocephaly in infants with congenital disorders such as congenital hip dislocation, bat ears, congenital scoliosis, and sternomastoid tumors and torticollis has been reported to be 60%, decreasing to 32% by adolescence. Forty-eight percent of normal healthy infants younger than 1 year had significant degrees of asymmetry, as did 14% of the normal adults.¹⁷

Pathogenesis and Pathology

The most common scenario whereby infants develop plagiocephaly involves positioning for sleep when they go home from the hospital after delivery. The infant is usually placed in the same position each night and other times that they sleep. The infant may turn its head toward the activity in the room. The child may have a preference of head turning secondary to neck tightness (torticollis) from perinatal causes. For what ever reason flatness is present, from birth or within the first month, a flat area develops behind one ear. Gravitational forces tend to further flatten the head. These forces are able to deform the skull rapidly owing to the mobility of the sutures and plasticity of the brain. These loose sutures allow for extensive head shape changes during delivery and passage of the head through the birth canal. The ability of the sutures to shift decreases quite rapidly during the first 2 months of life. A good example of gravitational deformation of the infant head is demonstrated by the shape changes seen in a balloon filled with water resting on a flat surface in Figure 185-1A.The bottom of the balloon becomes very flat. The top of the balloon flattens but to a lesser degree. The sides bulge but also sag, creating an asymmetric bulge in the sides of the balloon. Once the flatness of the skull begins, the infant’s head naturally rolls toward the flat spot, pulled by gravity, and it takes significant effort for the infant to hold the head in a neutral position. For the first 5 to 6 months, the flatness continues to increase. There is a compensatory asymmetry that is seen in the entire skull base, resulting in shift of ears, mandible, and orbits (Fig. 185-1B). The anterior cranial fossa also shows asymmetry. There is a parallelogram effect that explains the shift of the skull base (Fig. 185-1C). As the flatness begins on one side of the occiput, the occipital bone structures are pushed to the opposite side, resulting in a protrusion of the contralateral occipital structures. The frontal skull is misshapen because gravitational forces are acting in a greater force to the highest surface of the skull, and as gravity flattens the area contralateral to the occipital flatness, a similar shift of bony structures occurs in the forehead, resulting in a frontal protrusion. The sides of the head tilt toward the side of occipital flatness, and the shift to that side causes the ears to appear misaligned. In fact, the shift of structures in this manner involves the entire skull base, and thus there is shift of facial features, mandible, and orbits. When the infant begins to move and change position during sleep times and begins to roll over and spend more time upright, the progression of asymmetry arrests and over the next several months begins to correct itself by normal continued head growth. Seldom, however, will the asymmetry completely resolve. Studies have shown persistent asymmetry up to age 5 years.¹⁸ I re-examined more than 300 children treated for plagiocephaly 3 to 5 years after treatment and found the cranial vault asymmetry to average 5.4 mm. Asymmetry is occasionally found to persist into adulthood.

FIGURE 185-1 A, Photograph of water balloon on flat surface. B, Drawing of asymmetry of the infant head compared with balloon changes in shape due to gravitational forces. C, Drawing demonstrating the parallelogram effect and shifting of ear position.

Other, less frequent causes of asymmetry include multiple pregnancies, in which multiple infants share a restricted space in the womb and forces on the head are constant because of lack of room for the fetus to reposition.¹⁹ This restricted space in the womb also contributes to prenatal torticollis, thus complicating the ability to reposition the infant after delivery. Uterine malformations may contribute to the development of fetal plagiocephaly.^19,20 These infants are born with various types of deformation of the cranium. Many exhibit a form of “cranial scoliosis,” appearing like a “windswept” deformity in which the vertex of the cranium is pushed off to one side above the ears. These children usually exhibit associated variations of torticollis in which the neck is tilted to the side. This form of torticollis is difficult to correct because the muscle, ligaments, and at times, bones have grown in an asymmetric manner. The inverted position of the fetus with the head resting against bony prominences in the mother’s pelvis can also result in asymmetry. The development of plagiocephaly is more likely in the presence of torticollis. Torticollis is also presumed to occur because of neck position and stretch to the cervical musculature and ligaments during delivery, resulting in a painful “wry” neck.

Viral illnesses in the first month of life may result in a wry neck and torticollis. Torticollis may also result from constant preference of the infant to turn its head to only one side and then further add to the difficulty of repositioning later to correct the deformity. A retrospective study found that 95% of referrals for torticollis presented with plagiocephaly or facial asymmetry. The authors concluded that torticollis was secondary to plagiocephaly in 88% of patients.²¹

Prematurely born infants often develop various types of deformational skull deformity. These may be occipital plagiocephaly but usually result in scaphocephaly or dolichocephaly owing to the need to maintain airway for ventilation, which required the head be placed in a side-to-side position. Premature infants have even greater plasticity of skull and brain, and positional deformity can occur rapidly. Children with delayed neurological development or perinatal or infant brain injury due to infarction or trauma develop plagiocephaly many times owing to constant positioning in one direction or lack of head turning and activity.²² They remain in the supine position for greater lengths of time. Infants with neurological deficits due to brain development problems or perinatal injury may show a preference for turning their head to one side over the other owing to spasticity, dystonia, weakness, or neglect syndromes. Occipital flatness may occur on one side or the other, or the occiput may become symmetrically flat, depending on in what position the infant’s head remains. Treatment and reversal of this form of plagiocephaly are more difficult in these children because they are usually less likely to begin to increase their mobility to remain off the flat area because of their deficits. Furthermore, infants with hydrocephalus who undergo ventriculoperitoneal shunting are at increased susceptibility to deformational plagiocephaly due to the loss of physiologic maintenance of their cerebrospinal fluid dynamics.

Some studies have reported that plagiocephaly may cause developmental delay. One study reported that 39.7% of patients with persistent deformational plagiocephaly had received special educational services. Their siblings were used as controls and were found to have only a 7.7% incidence of receiving special educational services.²³ Another study reported that mental developmental index and the psychomotor developmental index scores were significantly different from the expected norms in plagiocephalic children evaluated with Bayley Scales of Infant Development II. In this study, 8.7% of children were categorized as severely delayed on the mental development index, compared with the expected normal population occurrence of 2.5%.^24,25