eMedicine Specialties > Neurology > Pediatric Neurology

Craniosynostosis

Author: Raj D Sheth, MD, Professor of Neurology, Mayo College of Medicine; Chief, Division of Pediatric Neurology, Nemours Children's Clinic
Coauthor(s): Philipp R Aldana, MD, FAAP, Assistant Professor of Neurosurgery and Pediatrics, University of Florida College of Medicine - Jacksonville; Director of Clinical Services, Pediatric Neurosurgery Center, University of Florida Health Sciences Center; Bermans J Iskandar, MD, Director, Associate Professor, Departments of Neurological Surgery, Pediatrics, Children's Hospital, University of Wisconsin Hospital and Clinics
Contributor Information and Disclosures

Updated: Nov 12, 2009

Introduction

Background

Craniosynostosis consists of premature fusion of 1 or more cranial sutures, often resulting in an abnormal head shape. It may result from a primary defect of ossification (primary craniosynostosis) or, more commonly, from a failure of brain growth (secondary craniosynostosis). Simple craniosynostosis is a term used when only 1 suture fuses prematurely. Complex or compound craniosynostosis is used to describe premature fusion of multiple sutures. When children with craniosynostosis, usually complex, also display other body deformities, this is termed syndromic craniosynostosis.

Also see eMedicine's Neurosurgery article on Craniosynostosis.

Pathophysiology

Normal skull development

Ossification of the cranial vault starts in the central region of each cranial bone and extends outward toward the cranial sutures.

Diagram of a neonate's skull demonstrating the lo...

Diagram of a neonate's skull demonstrating the location of the sutures.

Diagram of a neonate's skull demonstrating the lo...

Diagram of a neonate's skull demonstrating the location of the sutures.


  • The coronal suture separates the 2 frontal bones from the parietal bones.
  • The metopic suture separates the frontal bones.
  • The sagittal suture separates the 2 parietal bones.
  • The lambdoid suture separates the occipital bone from the 2 parietal bones.
  • The primary factor that keeps sutures open is ongoing brain growth.
  • Normal skull growth occurs perpendicular to each suture.

Primary craniosynostosis1

When 1 or more sutures fuse prematurely, skull growth can be restricted perpendicular to the suture. If multiple sutures fuse while the brain is still increasing in size, intracranial pressure can increase.

  • Scaphocephaly - Early fusion of the sagittal suture
  • Anterior plagiocephaly - Early fusion of 1 coronal suture
  • Brachycephaly - Early bilateral coronal suture fusion
  • Posterior plagiocephaly - Early closure of 1 lambdoid suture
  • Trigonocephaly - Early fusion of the metopic suture
Frontal view showing a fused and ridged metopic s...

Frontal view showing a fused and ridged metopic suture on 3-dimensional CT.

Frontal view showing a fused and ridged metopic s...

Frontal view showing a fused and ridged metopic suture on 3-dimensional CT.


Secondary craniosynostosis1

More frequent than the primary type, secondary craniosynostosis can result from early fusion of sutures due to primary failure of brain growth. Since brain growth drives the bony plates apart at the sutures, a primary lack of brain growth allows premature fusion of all the sutures.

CT image demonstrating features of secondary cran...

CT image demonstrating features of secondary craniosynostosis with cerebral atrophy. Cerebral atrophy is not present in primary craniosynostosis.

CT image demonstrating features of secondary cran...

CT image demonstrating features of secondary craniosynostosis with cerebral atrophy. Cerebral atrophy is not present in primary craniosynostosis.


Intracranial pressure is usually normal, and surgery is seldom needed. Typically, failure of brain growth results in microcephaly. Premature suture closure does not compromise brain growth and does not require surgery to open sutures.

Intrauterine space constraints may play a role in the premature fusion of sutures in the fetal skull.2 This has been demonstrated in coronal craniosynostosis. Other secondary causes of craniosynostosis include systemic disorders that affect bone metabolism such as rickets and hypercalcemia (see Causes).

Frequency

United States

Incidence of craniosynostosis is 0.04-0.1%. Of affected individuals, 2-8% have primary craniosynostosis. The remaining cases are secondary craniosynostosis, which frequently is accompanied by microcephaly. The frequencies of the various types of craniosynostosis are as follows: sagittal 50-58%, coronal 20-29%, metopic 4-10%, and lambdoid 2-4%.

Mortality/Morbidity

Raised intracranial pressure is rare with fusion of a single suture. It can occur in primary craniosynostosis when multiple sutures fuse.

  • Primary craniosynostosis: Although the major morbidity is cosmetic, intracranial pressure can be elevated. This occurs with a high frequency in multiple suture synostosis and rarely with single suture synostosis.
  • Secondary craniosynostosis: Typically no morbidity is noted, except that related to the underlying disorder. The lack of brain growth often is associated with neurodevelopmental delay.3,4
  • Craniosynostosis of 1-2 sutures: Cosmetic defect is the primary morbidity.

Sex

Craniosynostosis is equally distributed in both boys and girls.

Age

  • Neonatal period: Craniosynostosis is evident at birth when associated with other craniofacial abnormalities.
  • Infancy (0-18 mo): Secondary or primary craniosynostosis becomes evident as the child grows.

Clinical

History

  • Craniosynostosis may be evident at birth or in infancy from craniofacial abnormalities.
  • It may become evident later when the child exhibits neurodevelopmental delays.

Physical

Typically, careful examination alone can make the diagnosis.

  • Microcephaly usually suggests a secondary craniosynostosis.
  • Scaphocephaly
    • Premature fusion of the sagittal suture is the most common craniosynostosis, constituting more than half of all cases. It occurs frequently in premature infants.
    • The head typically is elongated in the anterior-posterior diameter and shortened in the biparietal diameter. Ridging of the sagittal suture is palpable.
  • Anterior plagiocephaly - Premature fusion of 1 coronal suture.
  • Brachycephaly
    • Premature fusion of both coronal sutures results in increased biparietal diameter. This anomaly is often syndromic. The skull is shorter in the anterior-posterior diameter.
    • Because the coronal suture develops in conjunction with the sutures at the base of the skull, unilateral or bilateral mid and upper face hypoplasia may occur. Orbits may be elliptical (ie, Harlequin features), and the supraorbital ridge may not be formed well.
    • Consider these features when planning surgery for brachycephaly.
  • Posterior plagiocephaly
    • The 2 predominant causes of posterior plagiocephaly are craniosynostosis of the lambdoid suture (<2%) or positional molding (vast majority).
    • Since the American Academy of Pediatrics recommended that infants sleep on their backs to reduce sudden infant death syndrome (SIDS) incidence, positional molding has been seen with increased frequency.5
    • Torticollis is frequently associated with positional molding.
    • Viewed from above, the head shape in positional molding resembles a parallelogram, whereas that in lambdoid craniosynostosis is trapezoid shaped.

      Positional molding. Note the anterior displacemen...

      Positional molding. Note the anterior displacement of the right occiput and of the right frontal region on the same side, which differentiate positional molding from posterior plagiocephaly craniosynostosis.

      Positional molding. Note the anterior displacemen...

      Positional molding. Note the anterior displacement of the right occiput and of the right frontal region on the same side, which differentiate positional molding from posterior plagiocephaly craniosynostosis.


      Posterior view of 3-dimensional cranial CT demons...

      Posterior view of 3-dimensional cranial CT demonstrating early fusion of the lambdoid suture.

      Posterior view of 3-dimensional cranial CT demons...

      Posterior view of 3-dimensional cranial CT demonstrating early fusion of the lambdoid suture.

    • In positional molding, ear position is more anterior on the side of flattening; in lambdoid synostosis, ear position is more posterior.
    • Frontal bossing is observed ipsilateral to the flattening in positional molding and contralateral in lambdoid synostosis.
  • Trigonocephaly
    • Premature fusion of the metopic suture frequently results in pointed forehead (ie, triangular shaped head). The abnormality is usually mild and requires no surgical intervention. Surgery is performed if the abnormality is persistent and severe.

    • Isolated fusion of the metopic suture. Note that ...

      Isolated fusion of the metopic suture. Note that the remaining sutures are open.

      Isolated fusion of the metopic suture. Note that ...

      Isolated fusion of the metopic suture. Note that the remaining sutures are open.


    • Trigonocephaly. Note the triangular shape of the ...

      Trigonocephaly. Note the triangular shape of the head.

      Trigonocephaly. Note the triangular shape of the ...

      Trigonocephaly. Note the triangular shape of the head.

    • Oxycephaly (ie, turricephaly) is fusion of all skull sutures and the sutures at the base of the skull.
  • Craniosynostosis sometimes is associated with sporadic craniofacial syndromes such as Crouzon, Apert, Chotzen, Pfeiffer, or Carpenter syndromes. In this context, facial features, typically craniofacial abnormalities, suture ridging, and early closure of fontanelles, suggest the diagnosis.
  • Kleeblattschãdel (ie, cloverleaf skull) results from fusion of all sutures except the metopic and squamosal sutures, giving the head a cloverleaf appearance.

  • Infant with primary craniosynostosis. The specifi...

    Infant with primary craniosynostosis. The specific deformity of the skull is Kleeblattschädel or cloverleaf skull.

    Infant with primary craniosynostosis. The specifi...

    Infant with primary craniosynostosis. The specific deformity of the skull is Kleeblattschädel or cloverleaf skull.

  • Intracranial pressure may be elevated in primary multiple suture craniosynostosis, such as cloverleaf skull and the syndromic synostoses. Signs include sun-setting eyes, papilledema, vomiting, and lethargy.

Causes

  • Multiple theories have been proposed for the etiology of primary craniosynostosis, but the most widely accepted is a primary defect in the mesenchymal layer ossification in the cranial bones.
  • Secondary craniosynostosis typically results from systemic disorders such as the following:
    • Endocrine - Hyperthyroidism, hypophosphatemia, vitamin D deficiency, renal osteodystrophy, hypercalcemia, and rickets
    • Hematologic disorders that cause bone marrow hyperplasia (eg, sickle cell disease, thalassemia)
    • Inadequate brain growth, including microcephaly and its causes and shunted hydrocephalus
  • The syndromic causes appear to result from genetic mutations responsible for fibroblast growth factor receptors 2 and 3. A gene locus for single suture craniosynostosis has not been identified.6
  • Other important factors to consider
    • Differentiating plagiocephaly that results from positional molding (which does not require surgery and is seen frequently) from lambdoid suture fusion is extremely important.
    • The presence of multiple suture fusions strongly suggests a craniofacial syndrome, which frequently requires the diagnostic expertise of a pediatric geneticist.

More on Craniosynostosis

Overview: Craniosynostosis
Differential Diagnoses & Workup: Craniosynostosis
Treatment & Medication: Craniosynostosis
Follow-up: Craniosynostosis
Multimedia: Craniosynostosis
References
Further Reading

References

  1. Jabs EW. Toward understanding the pathogenesis of craniosynostosis through clinical and molecular correlates. Clin Genet. Feb 1998;53(2):79-86. [Medline].

  2. Higginbottom MC, Jones KL, James HE. Intrauterine constraint and craniosynostosis. Neurosurgery. Jan 1980;6(1):39-44. [Medline].

  3. Sheth RD, Schaefer GB, Keller GM, et al. Size of the corpus callosum in cerebral palsy. J Neuroimaging. Jul 1996;6(3):180-3. [Medline].

  4. Schaefer GB, Sheth RD, Bodensteiner JB. Cerebral dysgenesis. An overview. Neurol Clin. Nov 1994;12(4):773-88. [Medline].

  5. Losee JE, Corde Mason A. Deformational plagiocephaly: diagnosis, prevention, and treatment. Clin Plast Surg. Jan 2005;32(1):53-64. [Medline].

  6. Robin NH. Molecular genetic advances in understanding craniosynostosis. Plast Reconstr Surg. Mar 1999;103(3):1060-70. [Medline].

  7. Anderson PJ, Netherway DJ, Abbott A, David DJ. Intracranial Volume Measurement of Metopic Craniosynostosis. J Craniofac Surg. 11 2004;15(6):1014-1016. [Medline].

  8. Cunningham ML, Heike CL. Evaluation of the infant with an abnormal skull shape. Curr Opin Pediatr. Dec 2007;19(6):645-51. [Medline].

  9. Dundulis JA, Becker DB, Govier DP, et al. Coronal ring involvement in patients treated for unilateral coronal craniosynostosis. Plast Reconstr Surg. Dec 2004;114(7):1695-703. [Medline].

  10. Elmslie FV, Reardon W. Craniofacial developmental abnormalities. Curr Opin Neurol. Apr 1998;11(2):103-8. [Medline].

  11. Fernbach SK. Craniosynostosis 1998: concepts and controversies. Pediatr Radiol. Sep 1998;28(9):722-8. [Medline].

  12. Liptak GS, Serletti JM. Pediatric approach to craniosynostosis. Pediatr Rev. Oct 1998;19(10):352; quiz 359. [Medline].

  13. Sheth RD, Mullett MD, Bodensteiner JB, Hobbs GR. Longitudinal head growth in developmentally normal preterm infants. Arch Pediatr Adolesc Med. Dec 1995;149(12):1358-61. [Medline].

Further Reading

See Medscape's Pediatrics/Neonatal Care Nursing Resource Center.

Keywords

craniosynostosis, abnormal head shape, ossification, primary craniosynostosis, failure of brain growth, secondary craniosynostosis, simple craniosynostosis, complex craniosynostosis, compound craniosynostosis, syndromic craniosynostosis, anterior plagiocephaly, Apert syndrome, brachycephaly, Carpenter syndrome, Chotzen syndrome, Crouzon syndrome, kleeblattschãdel, cloverleaf skull, oxycephaly, Pfeiffer syndrome, plagiocephaly, scaphocephaly, trigonocephaly

Contributor Information and Disclosures

Author

Raj D Sheth, MD, Professor of Neurology, Mayo College of Medicine; Chief, Division of Pediatric Neurology, Nemours Children's Clinic
Raj D Sheth, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American Epilepsy Society, American Neurological Association, and Child Neurology Society
Disclosure: Nothing to disclose.

Coauthor(s)

Philipp R Aldana, MD, FAAP, Assistant Professor of Neurosurgery and Pediatrics, University of Florida College of Medicine - Jacksonville; Director of Clinical Services, Pediatric Neurosurgery Center, University of Florida Health Sciences Center
Philipp R Aldana, MD, FAAP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Association of Neurological Surgeons, American Society of Pediatric Neurosurgeons, Children's Oncology Group, Congress of Neurological Surgeons, and International Society of Pediatric Neurosurgery
Disclosure: Nothing to disclose.

Bermans J Iskandar, MD, Director, Associate Professor, Departments of Neurological Surgery, Pediatrics, Children's Hospital, University of Wisconsin Hospital and Clinics
Bermans J Iskandar, MD is a member of the following medical societies: Alpha Omega Alpha and American College of Surgeons
Disclosure: Nothing to disclose.

Medical Editor

James J Riviello Jr, MD, George Peterkin Endowed Chair in Pediatrics, Professor of Pediatrics, Section of Neurology and Developmental Neuroscience, Professor of Neurology, Peter Kellaway Section of Neurophysiology, Baylor College of Medicine; Chief of Neurophysiology, Director of the Epilepsy and Neurophysiology Program, Texas Children's Hospital
James J Riviello Jr, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Kenneth J Mack, MD, PhD, Senior Associate Consultant, Department of Child and Adolescent Neurology, Mayo Clinic
Kenneth J Mack, MD, PhD is a member of the following medical societies: American Academy of Neurology, Child Neurology Society, Phi Beta Kappa, and Society for Neuroscience
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Amy Kao, MD, Assistant Professor, Department of Pediatrics, Division of Pediatric Neurology, Department of Neurology, Oregon Health and Science University; Consulting Staff, Shriners Hospital for Children
Amy Kao, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American Epilepsy Society, and Child Neurology Society
Disclosure: Nothing to disclose.

 
 
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