Deformational Plagiocephaly

10 Deformational Plagiocephaly


Correction with Repositioning and with Cranial Remodeling Orthosis


Olivier Vernet, Sandrine de Ribaupierre, and Bénédict Rilliet


Etymologically, the term plagiocephaly has Greek roots, plagios meaning “oblique” and kephale meaning “head.” Posterior plagiocephaly refers to a flattening of the occiput. It can be caused by lambdoid synostosis, which is an extremely rare condition. For the vast majority of affected infants, posterior plagiocephaly is the consequence of abnormal forces acting on an intrinsically normal, developing cranium. This situation has been referred to by many names, such as positional or deformational posterior plagiocephaly, benign positional molding, occipital plagiocephaly, and nonsynostotic occipital plagiocephaly.


In 1992 the American Academy of Pediatrics recommended that infants be placed on their backs to sleep, because prone and, to a lesser extent, side sleeping had been correlated with sudden infant death syndrome (SIDS).1Beginning in 1992, and following the “Back to Sleep” campaign,”2 numerous craniofacial centers documented an exponential increase in the diagnosis of posterior positional plagiocephaly (PPP).35 Following an initial period of diagnostic and surgical roaming,6 it became obvious that this abnormal skull shape was not the result of a craniosynostosis, but rather the consequence of unrelieved pressure onto the occiput during infant sleep.


Incidence


Premature lambdoid fusion is extremely rare; whereas the overall incidence of craniosynostosis is 6 per 10,000 live births, posterior plagiocephaly secondary to isolated lamb-doid premature fusion occurs in only 3 cases per 100,000 births.79 In contrast, over the past decade there was an increasing incidence of PPP,35 which was reported in up to 48% of live births.7,10 Three quarters of those patients with PPP were boys, and a majority of infants had right-sided plagiocephaly.2,4,7,1119


Pathophysiology


Regarding the pathophysiologic mechanism of PPP, it is admitted that external force applied consistently to a specific region of the infant’s head deforms the skull. If PPP is present at birth, it is likely the result of in utero or intrapartum molding. Associated conditions include uterine constraint such as multiple-infant birth, oligohydramnios, uterine malformation, macrocephaly, cervical spine anomaly or brain injury with asymmetrical spasticity, and birth injury associated with forceps or vacuum-assisted delivery.3,4,8,9,13,1823 Most of these cranial deformities improve spontaneously during the first months of life, except if the infant continues to rest his or her head on the flattened side of the occiput. In this situation, the occipital plagiocephaly may be perpetuated or become more pronounced by gravitational forces.24 Numerous babies, however, have at birth a round skull shape that may become flattened occipitally as a result of static supine positioning, because of the current advice to nurse them in a supine position to prevent SIDS and because neonates have limited cervical muscle strength.14,19 Mulliken et al19 discussed the unresolved controversy over whether torticollis is secondary to the abnormal head shape in PPP or is the cause of this cranial deformity. Because of the finding that an infant with PPP who lies supine on the flattened occiput can have either ipsilateral or contralateral shortening of the sternocleidomastoid muscle, these authors suggested that intrauterine (and cranial posture) was determinant.19


Diagnosis


It is important to distinguish lambdoid craniosynostosis from PPP, because the course and the management of these two conditions are clearly different. True synostosis is habitually present from birth and is progressive. It never improves spontaneously and confers the risk of intracranial hypertension, although this happens in < 10% of cases when only a single suture is involved.25


In contrast, PPP is often subtle and goes unnoticed or is absent at birth. It develops during the first months of age and confers no risk of raised intracranial pressure. Thus, the diagnosis of PPP is made primarily on the basis of history, with special attention to the antenatal period, looking for evidence of intrauterine constraint.


Simple physical examination usually confirms the diagnosis of PPP.7 In the vertex view, patients presenting with PPP demonstrate a parallelogram-shaped head: there is a flattening of one side of the posterior cranium, along with contralateral parieto occipital and ipsilateral frontal bossing, and the ipsilateral ear is displaced anteriorly. A cheekbone prominence may be observed ipsilaterally to the flattened occiput. Lambdoid synostosis also produces a flat occiput. However, in this situation, the vertex view reveals a trapezium-shaped head: there is a unilateral occipitoparietal flattening associated with contralateral frontal bossing. In addition, the area of the fused lambdoid suture may present as a bony ridge, with a bony prominence in the mastoid region behind the ear, which is displaced posteriorly and inferiorly.26 The severity of PPP may be assessed by anthropometric measurements using calipers: with the infant’s head held in a neutral position, two transverse fronto-occipital diameters are measured obliquely from each supraorbital region, to the parietooccipital region at the midpoint of the flattened area (short axis) and the contralateral point of maximal parietooccipital convexity (long axis). Additionally, anterior displacement of the ear ipsilateral to the flattened occiput may be evaluated by measuring the distance between the external auditory meatus and the external canthus on both sides. The physical examination should be completed with an assessment of neck movements to confirm or rule out the presence of torticollis.


Normally, there is no need for complementary radiologic investigations. However, if available, skull radiographs reveal in PPP a sclerotic margin parallel to a patent lambdoid suture on the side of the occipital flattening. This aspect, sometimes called “lazy lambdoid,” must not be confused with a true lambdoid synostosis, where the suture is no longer visible.15 Perisutural sclerosis, sutural narrowing, and increased digitations are not signs of impending synostosis.19,24


Treatment


The natural history of PPP is difficult to establish in the absence of reliable and reproducible data, which would allow practitioners to grade its severity. PPP has likely existed for centuries, although at a lower rate than today. This condition was probably less recognized in the past than over this last decade. It is estimated that > 70% of cases improve spontaneously.11 This improvement may be encouraged by regular change in sleeping position and physiotherapy.11,24,27 Severe positional skull deformations, however, may not always correct satisfactorily.3,28,29

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Jun 20, 2016 | Posted by in NEUROSURGERY | Comments Off on Deformational Plagiocephaly
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