Isolated Synostotic Plagiocephaly

Isolated synostotic plagiocephaly (ISP) presents as an oblique head as a consequence of an anomalous unilateral fusion of the coronal or the lambdoid suture [1]. In both cases, a palpable ridge will develop over the site of premature suture fusion [2]. Unilateral coronal synostosis is associated with anterior ISP while posterior ISP is caused by an early fusion of the lambdoid suture [3]. ISP affects approximately 1/100000 infants [4].

The genetic role in ISP is still in the focus of medical research. Rare mutations in the FGFRs, TWIST1, LRIT3, ALX4, IGFR1, EFNA4, RUNX2, and FREM1 genes may play a role for isolated ISP [3] [5] [6].

Anterior ISP-associated deformities include a flattening of the frontal bone and of the ipsilateral orbital rim in combination with a contralateral frontal bossing. In 50-60% of cases, strabismus is found as a consequence of anatomical changes in the orbital roof. Anterior ISP can also lead to a deviation of the skull base, a positional change of orbits, eyebrow and ear asymmetries, as well as mandibular deviations with malocclusion [3] [7] [8].

Posterior ISP leads to a trapezoid head shape with occiput flattening and malpositioned ears. Moreover, early lambdoid suture synostosis is linked to debilitating changes in the posterior fossa. Most notable findings in this context include an Arnold-Chiari malformation type 1 and a fusion of the jugular foramen. Thus, posterior ISP predisposes the patient for intracranial hypertension [9] [10].

ISP diagnosis relies on clinical findings and a thorough analysis excluding other potential causes of plagiocephaly. Plagiocephaly is clinically diagnosed by the typical formation of a parallelogram defined by ear and maxilla positions [1].

Positional plagiocephaly (PP) often occurs concomitantly with torticollis and produces stronger facial asymmetries [1] [11] [12]; ISP is most easily identified by the posterior malpositioning of the ear on the affected side. On the other hand, PP produces anteriorly malpositioned ears [2]. Syndromic plagiocephaly is usually accompanied by developmental retardation [13].

The use of computed tomography (CT) imaging is only indicated in case of an ISP suspicion, particularly if infant repositioning does not improve cranial asymmetry over weeks. CT findings can also be used in preparation for a surgical intervention aimed to avert an increased risk of intracranial hypertension (ICH) or to correct the plagiocephaly-caused malocclusion. If ICH has already developed, appropriate immediate countermeasures are indicated [1] [14].

1. Laughlin J, Luerssen TG, Dias MS. Committee On Practice Ambulatory Medicine. Prevention and Management of Positional Skull Deformities in Infants. Pediatrics. 2011;128(6): 1236–1241.
2. Biggs WS. Diagnosis and Management of Positional Head Deformity. Am Fam Physician. 2003; 67(9):1953-1956.
3. Ghizoni E, Denadai R, Raposo-Amaral CA, Joaquim AF, Tedeschi H, Raposo-Amaral CE. Diagnosis of infant synostotic and nonsynostotic cranial deformities: a review for pediatricians. Rev Paul Pediatr. 2016; 34(4): 495–502.
4. Bruneteau RJ, Mulliken JB. Frontal plagiocephaly: synostotic, compensational, or deformational. Plast Reconstr Surg. 1992;89(1):21–31.
5. Heuzé Y, Holmes G, Peter I, Richtsmeier JT, Jabs EW. Closing the gap: genetic and genomic continuum from syndromic to nonsyndromic craniosynostoses. Curr Genet Med Rep. 2014;2(3):135–145.
6. Johnson D, Wilkie AO. Craniosynostosis. Eur J Hum Genet. 2011;19(4):369–376.
7. Raposo-do-Amaral CE, Silva MP, Menon DN, Somensi RS, Raposo-do-Amaral CA, Buzzo CL. Estudo antropométrico das assimetrias craniofaciais na craniossinostose coronal unilateral. Rev Bras Cir Plast. 2011;26(1):27–31.
8. Raposo-do-Amaral CE, Raposo-do-Amaral CA, Guidi MC, Buzzo CL. Prevalência do estrabismo na craniossinostose coronal unilateral. Há benefício com a cirurgia craniofacial? Rev Bras Cir Craniomaxilofac. 2010;13(2):73–77.
9. Matushita H, Alonso N, Cardeal DD, Andrade FG. Major clinical features of synostotic occipital plagiocephaly: mechanisms of cranial deformations. Childs Nerv Syst. 2014;30(7):1217–1224.
10. Tamburrini G, Caldarelli M, Massimi L, Gasparini G, Pelo S, Di Rocco C. Complex craniosynostoses: a review of the prominent clinical features and the related management strategies. Childs Nerv Syst. 2012;28(9):1511–1523.
11. Davis B, Moon R, Schas H, Ottolini M. Effects of sleep position on infant motor development. Pediatrics. 1998;102(5):1135–1140.
12. de Chalain T, Park S. Torticollis associated with positional plagiocephaly: a growing epidemic. J Craniofac Surg. 2005;16(3):411–418.
13. Kimonis V, Gold JA, Hoffman TL, Panchal J, Boyadjiev SA. Genetics of craniosynostosis. Semin Pediatr Neurol. 2007;14(3): 150–161.
14. Robinson S, Proctor M. Diagnosis and management of deformational plagiocephaly. J Neurosurg Pediatr. 2009;3(4):284–295.