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Craniosynostosis
Craniosynostosis RE Bristol, Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, USA SP Beals, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ, USA r 2014 Elsevier Inc. All rights reserved. This article is a revision of the previous edition article by Stephen P Beals, volume 1, pp 792–794 r 2003, Elsevier Inc.
Introduction
History
Craniosynostosis is a congenital skull abnormality in which one or more of the cranial sutures fuse prematurely (Figure 1). The birth prevalence is believed to be 340–475 per 1 million births. The condition may begin prenatally or postnatally. It is often associated with facial and skull malformation and thus requires a corrective surgical approach that addresses the deformity of the cranial vault, skull base, and all involved facial components. The severity of craniosynostosis can vary widely, depending on the number and degree of sutures involved (Figure 2). It is often categorized as single or multiple, primary or secondary, and isolated or syndromic. With little longitudinal research in this area, the risks and benefits of surgery must be weighed carefully. In the mildest cases of single-suture synostosis, there may be no evidence of acute impairment of brain growth, and craniofacial asymmetry may be inconspicuous. In more severe cases involving multiple sutures, a child may experience considerable restriction of brain growth and show evidence of increased intracranial pressure, related neurological compromise, and possibly blindness or even death.
In 1839, Sommerring reported that bone growth occurred at the sutures and that growth was reduced perpendicularly to the axis of a fused suture. In 1830, Otto had made similar observations. By 1851, Virchow had coined the term craniostenosis, which is often used interchangeably with craniosynostosis, and had elaborated on the restricted growth perpendicular to the suture and the enhanced growth parallel to it. He also described the distinctive compensatory changes in the calvaria (vault of the cranium) to accommodate brain growth. Moss challenged this scenario by proposing the cranial base rather than the calvarial suture as the focal point in the development of skull abnormalities. Today, there is evidence that craniosynostosis begins at one point and spreads along the suture line, thus perpetuating premature accelerated bone growth of unknown origin. At the turn of the nineteenth century, neurosurgeons began to perform decompression procedures on patients with craniosynostosis. In 1927, Faber and Towne described craniectomies along with Lane and Lannelongue, who used linear craniectomies, elevation of bone flaps, and osteotomies with inconsistent results. Simultaneously, craniofacial surgical principles were being used to treat craniosynostosis and were revolutionized by Tessier by the 1960s. Since the dawn of the twentieth century, hundreds of papers have been published about craniosynostosis. Many of the basic techniques and principles, although now refined, are still embraced.
Metopic suture
Etiology and Pathology Coronal suture
Sagittal suture
The etiology of craniosynostosis is still being studied. It is widely believed that craniosynostosis is pathogenetic or heterogeneous and that nonsyndromic cases occur as a result of a primary pathology of the suture, whether it originates genetically, biochemically, or metabolically or whether it is even due to fetal head constraint. Current research suggesting possible interference with bony development at the level of the mesenchyme has led to studies related to transforming growth factor-b and fibroblast growth factor receptors (FGFRs). These exciting advances in genetic research have helped researchers interpret the pathogenesis of different phenotypes in craniosynostosis.
Craniofacial Syndromes Lambdoid suture
Figure 1 Normal infant skull with sutures identified. Reproduced with permission from the Barrow Neurological Institute.
894
Premature closure of various cranial sutures is typical of Crouzon’s disease (craniofacial dysostosis) and Apert’s and related syndromes (acrocephalosyndactyly) such as Vogt’s
Encyclopedia of the Neurological Sciences, Volume 1
doi:10.1016/B978-0-12-385157-4.00737-5
Craniosynostosis
895
syndrome, Saethre–Chotzen’s syndrome, acrocephalosyndactyly IV syndrome, Pfeiffer’s syndrome, Carpenter’s syndrome, and Cloverleaf skull deformity. The classification of craniofacial syndromes is being viewed from a new perspective since the discovery of FGFR mutations.
Treatment
(a) Scaphocephaly
(b) Oxycephaly
The most common treatment for craniosynostosis is surgery. In severe cases and cases involving syndromes, treatment depends on severity; age at presentation; and the presence of other airway, visual, or neurological complications. In other instances, secondary surgery is required to address bony defects, secondary asymmetry, and orthognathic (correcting deformities of the jaw and associated malocclusion) and orbital issues. In patients with single-suture synostosis, surgery in the first 6 months of life is usually sufficient. Advances in minimally invasive surgical techniques have broadened the options for the treatment of craniosynostosis. For sagittal synostosis, excellent results can be obtained with a minimally invasive, or endoscopic, synostectomy followed by dynamic orthosis. Similarly, distraction techniques have been used to enlarge the calvarial vault in patient with multisuture or syndromic synostosis.
Outcomes
(c) Brachycephaly
(d) Plagiocephaly
Outcomes related to craniofacial surgery have been documented for many decades. Although medical advances have made these procedures safer to perform, many specific ramifications are still elusive. Morbidity and mortality rates documented for many different craniofacial procedures still vary when related to specific techniques and their associated risks. Definitive data are lacking. Overall, complication rates have improved, but the choice of timing and whether the surgery is safe are decisions best left to individual surgeons. Opinions on the optimal type of fixation and the use of bone substitutes also vary. Final aesthetic outcomes are declared promising but again are difficult to objectify. Widely accepted techniques of anthropometry, cephalometry, and computerassisted tomography are the preferred tools that surgeons can use to quantify successful changes as a result of surgery. However, limitations related to the reliability and accuracy of data collection, transferability of biplanar data, labor intensity, and cost persist. Consequently, long-term, single-center, experimentally sound data are not readily available.
See also: Brain Development, Normal Postnatal. Craniectomy (e) Trigonocephaly
Figure 2 (a) Sagittal synostosis causes scaphocephaly. (b) Bilateral coronal synostosis causes oxycephaly. (c) Bilateral coronal synostosis causes brachycephaly. (d) Unilateral coronal synostosis causes plagiocephaly. (e) Metopic synostosis causes trigonocephaly. Reproduced with permission from the Barrow Neurological Institute.
Further Reading Cohen Jr. MM and MacLean RE (eds.) (2000) Craniosynostosis. Diagnosis, Evaluation and Management. New York: Oxford University Press. Marsh J (2000) Surgical research on craniosynostosis. In: Cohen Jr. MM and MacLean RE (eds.) Craniosynostosis. Diagnosis, Evaluation and Management, 2nd edn., pp. 292–306. New York: Oxford University Press.
Introduction
History
Craniosynostosis is a congenital skull abnormality in which one or more of the cranial sutures fuse prematurely (Figure 1). The birth prevalence is believed to be 340–475 per 1 million births. The condition may begin prenatally or postnatally. It is often associated with facial and skull malformation and thus requires a corrective surgical approach that addresses the deformity of the cranial vault, skull base, and all involved facial components. The severity of craniosynostosis can vary widely, depending on the number and degree of sutures involved (Figure 2). It is often categorized as single or multiple, primary or secondary, and isolated or syndromic. With little longitudinal research in this area, the risks and benefits of surgery must be weighed carefully. In the mildest cases of single-suture synostosis, there may be no evidence of acute impairment of brain growth, and craniofacial asymmetry may be inconspicuous. In more severe cases involving multiple sutures, a child may experience considerable restriction of brain growth and show evidence of increased intracranial pressure, related neurological compromise, and possibly blindness or even death.
In 1839, Sommerring reported that bone growth occurred at the sutures and that growth was reduced perpendicularly to the axis of a fused suture. In 1830, Otto had made similar observations. By 1851, Virchow had coined the term craniostenosis, which is often used interchangeably with craniosynostosis, and had elaborated on the restricted growth perpendicular to the suture and the enhanced growth parallel to it. He also described the distinctive compensatory changes in the calvaria (vault of the cranium) to accommodate brain growth. Moss challenged this scenario by proposing the cranial base rather than the calvarial suture as the focal point in the development of skull abnormalities. Today, there is evidence that craniosynostosis begins at one point and spreads along the suture line, thus perpetuating premature accelerated bone growth of unknown origin. At the turn of the nineteenth century, neurosurgeons began to perform decompression procedures on patients with craniosynostosis. In 1927, Faber and Towne described craniectomies along with Lane and Lannelongue, who used linear craniectomies, elevation of bone flaps, and osteotomies with inconsistent results. Simultaneously, craniofacial surgical principles were being used to treat craniosynostosis and were revolutionized by Tessier by the 1960s. Since the dawn of the twentieth century, hundreds of papers have been published about craniosynostosis. Many of the basic techniques and principles, although now refined, are still embraced.
Metopic suture
Etiology and Pathology Coronal suture
Sagittal suture
The etiology of craniosynostosis is still being studied. It is widely believed that craniosynostosis is pathogenetic or heterogeneous and that nonsyndromic cases occur as a result of a primary pathology of the suture, whether it originates genetically, biochemically, or metabolically or whether it is even due to fetal head constraint. Current research suggesting possible interference with bony development at the level of the mesenchyme has led to studies related to transforming growth factor-b and fibroblast growth factor receptors (FGFRs). These exciting advances in genetic research have helped researchers interpret the pathogenesis of different phenotypes in craniosynostosis.
Craniofacial Syndromes Lambdoid suture
Figure 1 Normal infant skull with sutures identified. Reproduced with permission from the Barrow Neurological Institute.
894
Premature closure of various cranial sutures is typical of Crouzon’s disease (craniofacial dysostosis) and Apert’s and related syndromes (acrocephalosyndactyly) such as Vogt’s
Encyclopedia of the Neurological Sciences, Volume 1
doi:10.1016/B978-0-12-385157-4.00737-5
Craniosynostosis
895
syndrome, Saethre–Chotzen’s syndrome, acrocephalosyndactyly IV syndrome, Pfeiffer’s syndrome, Carpenter’s syndrome, and Cloverleaf skull deformity. The classification of craniofacial syndromes is being viewed from a new perspective since the discovery of FGFR mutations.
Treatment
(a) Scaphocephaly
(b) Oxycephaly
The most common treatment for craniosynostosis is surgery. In severe cases and cases involving syndromes, treatment depends on severity; age at presentation; and the presence of other airway, visual, or neurological complications. In other instances, secondary surgery is required to address bony defects, secondary asymmetry, and orthognathic (correcting deformities of the jaw and associated malocclusion) and orbital issues. In patients with single-suture synostosis, surgery in the first 6 months of life is usually sufficient. Advances in minimally invasive surgical techniques have broadened the options for the treatment of craniosynostosis. For sagittal synostosis, excellent results can be obtained with a minimally invasive, or endoscopic, synostectomy followed by dynamic orthosis. Similarly, distraction techniques have been used to enlarge the calvarial vault in patient with multisuture or syndromic synostosis.
Outcomes
(c) Brachycephaly
(d) Plagiocephaly
Outcomes related to craniofacial surgery have been documented for many decades. Although medical advances have made these procedures safer to perform, many specific ramifications are still elusive. Morbidity and mortality rates documented for many different craniofacial procedures still vary when related to specific techniques and their associated risks. Definitive data are lacking. Overall, complication rates have improved, but the choice of timing and whether the surgery is safe are decisions best left to individual surgeons. Opinions on the optimal type of fixation and the use of bone substitutes also vary. Final aesthetic outcomes are declared promising but again are difficult to objectify. Widely accepted techniques of anthropometry, cephalometry, and computerassisted tomography are the preferred tools that surgeons can use to quantify successful changes as a result of surgery. However, limitations related to the reliability and accuracy of data collection, transferability of biplanar data, labor intensity, and cost persist. Consequently, long-term, single-center, experimentally sound data are not readily available.
See also: Brain Development, Normal Postnatal. Craniectomy (e) Trigonocephaly
Figure 2 (a) Sagittal synostosis causes scaphocephaly. (b) Bilateral coronal synostosis causes oxycephaly. (c) Bilateral coronal synostosis causes brachycephaly. (d) Unilateral coronal synostosis causes plagiocephaly. (e) Metopic synostosis causes trigonocephaly. Reproduced with permission from the Barrow Neurological Institute.
Further Reading Cohen Jr. MM and MacLean RE (eds.) (2000) Craniosynostosis. Diagnosis, Evaluation and Management. New York: Oxford University Press. Marsh J (2000) Surgical research on craniosynostosis. In: Cohen Jr. MM and MacLean RE (eds.) Craniosynostosis. Diagnosis, Evaluation and Management, 2nd edn., pp. 292–306. New York: Oxford University Press.