AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

The term craniosynostosis refers to the premature fusion of one or multiple cranial sutures. Craniosynostosis is commonly present at birth but is not always noticeable, especially when mild. It certainly manifests as a clinical deformity in the first few months of life. Apart from the obvious cosmetic facial and cranial deformity, early closure of sutures can cause intracranial hypertension and adversely affect development in some patients.

History of the Procedure

Otto recognized the first premature closure of sutures as a discrete clinical entity in 1830 and coined the term craniosynostosis. Stahl and Hyrtl noticed that premature closure of the cranial vault sutures leads to an abnormal skull shape. In 1851, Virchow described how skull growth is restricted to a plane perpendicular to the affected, prematurely fused suture and is enhanced in a plane parallel to it. For almost a century, this has been the main theory explaining the observed cranial deformities. Virchow was the first person to classify the different types of skull deformity seen in persons with craniosynostosis and introduced the morphological descriptive terms still in use today.

Observations from Crouzon and Apert from 1910 to the 1920s led to the realization that in some cases, cranial and facial deformity was only part of a wider complex of deformities, constituting the respectively named syndromes (Crouzon and Apert syndromes) that included abnormal development of the facial skeleton (Crouzon syndrome) and associated limb deformities (Apert syndrome).

In the 1950s, Moss pointed out that removal of the affected suture does not alter the abnormal skull growth and demonstrated skull base abnormalities in patients with sagittal and bicoronal synostosis. He concluded that the main mechanism leading to cranial deformity in most types of craniosynostosis was abnormal growth at the level of the skull base, rather than the actual fused sutures, and that skull growth follows brain development.

His views changed the entire concept of surgical treatment of craniosynostosis, moving it from excision of affected sutures with linear craniectomies to complex cranial expansion procedures, addressing the restriction at the skull base. Tessier pioneered the latter procedures in the early 1960s and is regarded as the father of modern craniofacial surgery. He was the first to attempt major surgical procedures on the craniofacial skeleton. Initially, he performed surgical procedures as part of reconstructive surgery after trauma, but later, he attempted surgical procedures on patients with craniosynostosis. Starting with adults and extending his techniques to children, he attempted various procedures, including fronto-orbital and midface advancements, both separately and as monobloc procedures.

The introduction of computed tomography (CT) in the late 1970s offered a new tool for visualizing the anatomical deformities that is more accurate than plain radiographs. The introduction of the CT scan gave rise to a new perspective into skull growth and resulted in the concept of 3-dimensional skull growth and deformity in disease states. Although Virchow initially focused his attention on the skull vault and Moss later focused his attention on the skull base in a mutually exclusive manner, the introduction of CT scans signaled a new era and effected an amalgamation of their views. Serial visualization of the evolving deformity and assessment of the effects of surgery using CT scan images offered clinicians the opportunity to monitor the effect of craniosynostosis on skull growth. Subsequent technological improvements led to 3-dimensional reconstruction of CT scan images, which produced a realistic 3-dimensional visual impression of the skull and improved understanding of the condition.

Problem

Two ways of describing the types of craniosynostosis exist, according to the clinical deformity itself or the affected sutures. Virchow, influenced by then prevailing anthropological concepts, developed the former. The latter was developed by Ingraham and Matson and is based mainly on radiological evidence of fused sutures. To a large extent, correspondence between the 2 nomenclatures exists, better appreciated in single suture forms of craniosynostosis. Image 1 shows in diagrammatic fashion the main deformities in the most common types of craniosynostosis.

Scaphocephaly is derived from the Greek words scaphos, meaning boat, and kephali, meaning head. Scaphocephaly corresponds to sagittal synostosis.

Plagiocephaly is derived from the Greek word plagios, meaning oblique or sloping, and corresponds to unilateral coronal synostosis. The term posterior plagiocephaly corresponds to lambdoid synostosis.

Trigonocephaly is derived from the Greek word trigonos, meaning triangular, and corresponds to metopic synostosis.

The terms brachycephaly, oxycephaly, and turricephaly are used for various forms of synostosis affecting both coronal sutures in the former or in combination with the sagittal and sphenofrontal sutures in the latter forms, usually encountered in syndromic types. Brachycephaly is derived from the Greek word brachys, meaning short.

Oxycephaly is derived from the Greek word oxys, meaning sharp, and is a high, conical head with sharp bossing in the region of the anterior fontanelle.

Turricephaly is derived from the Latin word turris, meaning tall, and is a round head, like a tower.

Cloverleaf skull deformity, triphyllocephaly (derived from the Greek word triphyllos, meaning trefoil, with 3 leaves), is a specific type of multiple suture synostosis characterized by a head shaped like a cloverleaf or trefoil, which is a trilobular head with pronounced constrictions in both sylvian fissures and bulging temporal regions.

German terms occasionally appear in the literature. Turmschädel means turricephaly, and kleeblattschädel means cloverleaf skull deformity. Classification into nonsyndromic and syndromic forms is commonly used in clinical practice. Nonsyndromic forms of craniosynostosis include single-suture and multiple-suture synostosis not associated with any other syndromic features. Of the single-suture craniosynostoses, the most common in order of incidence are sagittal, unilateral coronal, and metopic synostosis, constituting, respectively, 35%, 15%, and 5% of all cases of craniosynostosis.

In the group of nonsyndromic multiple-suture synostoses, various types can be included, not all of which have been clearly defined. The most common is bilateral coronal synostosis, which is characterized by brachycephaly. Oxycephaly is a variation of the complex, multiple-suture, nonsyndromic form and usually results from a combination of bilateral coronal, sagittal, and, possibly, lambdoid synostosis, resulting in the characteristic head shape. Cloverleaf skull deformity is a separate entity characterized by a typical head shape due to bilateral constrictions at the sylvian fissures. Complex multiple-suture synostosis, often referred to as pansynostosis, includes various deformities involving multiple sutures in patterns not conforming to any of the other types. Complex multiple-suture synostosis is a mixture of otherwise unclassifiable combinations of affected sutures.

Craniosynostosis is also seen in the context of various syndromes (>70). The most common syndromes encountered in clinical practice are Crouzon, Apert, Saethre-Chotzen, and Pfeiffer. These syndromes are all characterized by bilateral coronal synostosis of varying severity, often combined with some degree of sagittal synostosis. The typically observed brachycephaly is due to a shortened anteroposterior diameter of the skull and corresponding enlargement of the bitemporal and biparietal diameter. Other suture involvement can result in oxycephaly, scaphocephaly, and turricephaly. Combinations of all these deformities can be seen in complex cases.

A flat forehead and characteristically low-set ears are common. Patients, particularly those with Apert syndrome, tend to develop turricephaly (see Image 2), a feature not commonly seen in persons with other syndromic forms. Other extracranial abnormalities are commonly observed as part of the syndromes. In those with Crouzon or Apert syndromes, maxillary hypoplasia is present in varying degrees. Syndactyly of hands and feet (acrocephalosyndactyly) is a prominent feature of Apert syndrome. Bilateral ptosis is common in the context of Saethre-Chotzen syndrome and usually requires surgical treatment. Down slanting of the palpebral fissures is characteristic of Pfeiffer syndrome. In most forms of coronal synostosis, a variable degree of exophthalmos is present

Frequency

The overall incidence of craniosynostosis is estimated as 1 case in 2000 live births. Crouzon syndrome has an incidence of 1 case in 60,000 live births. Apert syndrome has an incidence of 1 case in 10,000 live births. Saethre-Chotzen and Pfeiffer syndromes are much less common.

Etiology

The etiology of craniosynostosis is not clear at present, but genetic defects are becoming increasingly recognized. In 1912, Crouzon was the first to recognize an inheritance pattern in the syndrome that he described first as craniofacial dysostosis. He described a family in which the syndrome had been passed on vertically with a pattern similar to autosomal dominance. For several decades, little further progress was made. Renewed interest and considerable advances in the techniques used in studying genetics in the last few years have contributed considerably to advancing knowledge on important genetic aspects of craniosynostosis.

Autosomal dominant inheritance has been clearly identified in syndromic forms of craniosynostosis, although a number of patients have spontaneous new mutations. Familial cases are frequent, constituting from 25-46% of the total number of cases, variable for the different syndromes. Complete penetrance has been observed in all inherited cases. No inheritance pattern has been identified for nonsyndromic forms of craniosynostosis, although a familial occurrence has been observed in 4-10% of the patients, variable for the different types of syndromes. In familial cases, variable vertical and horizontal penetrance has been observed.

A major breakthrough in understanding the genetic background of craniosynostosis has been the identification of genetic defects in several syndromes, including the 3 most common: Crouzon, Apert, and Pfeiffer. The presence of mutations in the group of genes coding for fibroblast growth factor receptor (FGFR) in patients with Apert, Crouzon, and Pfeiffer syndromes is now clearly established. These genes (currently, 4 are identified) code for receptors on the cell surface, which mediate the effects of fibroblast growth factors (FGF). The effects of FGFs are not fully understood, but they are already clearly implicated in important cellular processes such as cell growth, differentiation, migration, and survival. Although the 4 different genes are located in different chromosomes, the receptor proteins they encode for are very similar structurally.

Almost all cases of Apert syndrome are due to 1 of the 2 described mutations of the FGFR2 gene, located on chromosome 7. For Crouzon and Pfeiffer syndromes, the situation is less clear. Additional abnormalities of chromosome 10 have been identified. Currently, 25 mutations have been identified on the FGFR2 gene and implicated in the pathogenesis of Crouzon syndrome. Mutations of both FGFR1 and FGFR2 genes have been described in Pfeiffer syndrome, each corresponding to phenotypes of different clinical severity. No genetic defects have been identified in nonsyndromic forms of craniosynostosis. In the next few years, substantial progress is anticipated in this field, adding to the current knowledge on the underlying operative pathophysiological mechanisms for different forms of craniosynostosis. As yet, the effector link between the chromosomal defect and the actual premature fusion of the sutures has not been identified.

Pathophysiology

Using immunocytochemistry techniques, abnormal osteoblastic activity has been observed in cultures of synostotic bone in which decreased growth rate; decreased alkaline phosphatase production; and increased levels of osteocalcin, platelet-derived growth factor, and epidermal growth factor have been observed. Histopathological examination of resected sutures has shown various stages of new bone formation across the area of the suture. These stages range from trabecular interdigitation across the fibrous tissue of the suture to frank bony fusion and overproduction, resulting in ridge formation on the site of the affected suture, which is palpable upon clinical examination and observed at operation and is prominent on the inner table of the skull.

Clinical

Apart from the obvious clinical deformity affecting the face and head, children can have airway problems, especially children with the syndromic form of craniosynostosis. Because of the hypoplastic maxilla, these children have difficulty breathing through their nose and end up breathing through their mouth. At night, these children can have sleep apnea. This affects not only their growth pattern, but also their behavior and speech. Children with raised intracranial pressure (ICP) can experience chronic headaches, declining school performance, and gradual visual failure. As children grow, abnormal facial appearance has a negative effect on their social integration, with a corresponding effect on personality development.

A small minority of children present late. These children have mild deformity that is unnoticed in the first few months and years of life, and they present when aged 4-8 years with symptoms of raised ICP.

One should clearly distinguish children who have a flattened posterior part of the head on one or both sides without having premature fusion of the lambdoid sutures. This condition is often called moulding or positional posterior plagiocephaly and rarely requires surgical treatment. This condition manifests with skull flattening, which is usually not progressive and is considered to be due to the position the head takes during sleep.

INDICATIONS

Section 3 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

No medical treatment exists for craniosynostosis. Indications for surgical treatment in the form of cranial expansion in the first few months of life include progressive facial and cranial deformity, intracranial hypertension, and progressive exophthalmos threatening the eyes.

Later on, children aged 5-10 years may develop recurrent craniostenosis and may require repeat operations.

In children with the syndromic form of craniosynostosis, progressive maxillary hypoplasia causes breathing problems and difficulties because of poor dentition apposition. Surgical treatment, in the form of midface advancement, is common in children aged 10-15 years.

RELEVANT ANATOMY

Section 4 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

During the clinical examination, observing the position of the eyebrows, eyes, nose, cheeks, mandibles, and ears is important. Displacement of one eyebrow downwards may indicate early fusion of the coronal suture on that side. Wide disposition of the eyes, which gives the appearance of a broad root of the nose, may indicate hypertelorism, seen as part of facial clefts. Narrow disposition of the eyes may indicate early fusion of the metopic suture. Proptosis of the eyeballs (exophthalmos) may indicate shallow orbits, which are seen in the presence of bilateral coronal synostosis. Curvature of the nose (facial scoliosis) is seen in unilateral coronal synostosis and syndromes that produce mandibular hypoplasia. Atrophic cheeks are seen in syndromes that cause midface hypoplasia. This is often accompanied by oral malocclusion because the upper jaw is recessed and cannot appose the lower jaw, as in healthy individuals.

Unilateral or bilateral atrophic mandible is seen in the context of various forms of hemifacial microsomia. Anterior and downward displacement of the ears may indicate a skull base deformity, which usually coexists as part of premature suture closure.

Of surgical importance is the configuration of the bony skeleton of the orbits, the anterior fossa floor, and the temporal regions. These are the sites at which osteotomies are commonly performed during corrective surgery. Useful anatomical information is extracted from 3-dimensional CT (3D-CT) scan images of bone windows. The surgeon can appreciate the morphology in the sites of interest and can formulate a plan for how far the supraorbital bar of the frontal bone must be advanced to correct the orbits. Similarly, with deformities that affect the posterior part of the skull, the surgeon can appreciate the relationship of the deformity to the sagittal sinus and the foramen magnum and can formulate a surgical plan accordingly.

CONTRAINDICATIONS

Section 5 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

In severe cases, other congenital problems, such as heart or lung disorders, may represent contraindication to surgical treatment if the child is not fit to undergo general anesthesia. In the rare occasions in which a blood dyscrasia is present, this requires appropriate preoperative, intraoperative, and postoperative management to avoid excess blood loss. In rare severe cases in which multiple other congenital deformities exist, the life expectancy may be poor, and, in such cases, surgeons may believe that surgical correction of craniosynostosis may not be appropriate.

WORKUP

Section 6 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Lab Studies

• No particular laboratory tests are specific to the workup for craniosynostosis. All patients undergoing surgical treatment have their hemoglobin and electrolyte levels checked to ensure these levels are within the reference range so they can be submitted to general anesthesia.
• In some units, anticoagulation studies are performed preoperatively, although this is not a universal policy. Certainly, craniofacial deformities are not associated with an increased risk of coagulation defects.
• Cranial remodeling operations are associated with significant blood loss, and the usual practice is to secure at least 3 units of suitable cross-matched blood before surgery. As part of general investigations, blood samples are obtained for use in chromosomal analysis.

Imaging Studies

• From the early days of craniofacial surgery, radiological investigations were used to study the morphology of the cranial and facial skeleton and monitor the effects of corrective surgery. Initially, plain radiographs, later CT scan, and recently MRI have been used both in clinical practice for preoperative planning and postoperative follow-up and in research, exploring the pathophysiological mechanisms implicated in causing the skull deformity. Common practice in most units includes at least plain radiographs and CT scans prior to surgery. MRI scans are used in long-term follow-up of syndromic cases or in children presenting late, after the first few months of life.
• Plain radiographs are easy to obtain and demonstrate osseous anatomy well. Plain radiographs are used extensively in patients with craniosynostosis. They are useful for identifying the prematurely fused sutures; demonstrating the overall morphology of the cranium; identifying the presence of localized problems, eg, constricting bony bands impairing growth; and identifying the presence of generalized problems, eg, the copper-beaten appearance, indicating intracranial hypertension (see Image 3).
• • Serial radiographs in borderline cases or in patients with possible recurrent stenosis after surgical treatment are used to assess the evolution of the deformity.
  • The use of standardized views allows measurement of cephalometric features and serial follow-up. Several indices have been devised and used for comparisons. The most popular index has been the cranial index described by Cronqvist. A considerable body of scientific work exists that explores the value of cephalometric studies on the growth of the head and face in a normal state and in craniosynostosis, in which the effect of corrective surgery can be monitored.
  • Growth of the cranial vault and maturation of the facial skeleton have been demonstrated to occur at different ages. Also, different types of craniosynostosis have been shown to have differential growth of the skull vault and skull base, caused by differential pathological involvement of the sutures of the anterior and posterior skull base, supporting earlier views that the sutures of the skull base are implicated in the morphogenesis of some types of craniosynostosis.
  • In the case of positional posterior plagiocephaly, the plain skull radiographs show normal lambdoid sutures.
• The introduction of CT scan provided a more detailed way of visualizing the intracranial pathologic condition. Visualization of detailed anatomy of the calvaria and the brain parenchyma became possible. The fused sutures are clearly identified; the abnormal contour of the skull is better appreciated; and the associated cerebral abnormalities, such as hydrocephalus, are demonstrated (see Image 4). The relationship of soft and hard tissues of the craniofacial skeleton can be studied in detail. The skull base in particular, which is not clear on plain radiographs, is clear on CT scan images.
• • The principle of cephalometry has also been applied to CT scans. Using various fixed bony landmarks, the growth of various parts of the skull, in particular the skull base and orbital complex, have been investigated in the normal state and in craniosynostosis, and the effect of corrective surgery has been quantified. Skull base growth has been demonstrated to be different in the various types of craniosynostosis, depending on the involved prematurely fused suture, and is morphologically more abnormal for single-suture and nonsyndromic bilateral coronal synostoses than for syndromic forms. In syndromic craniosynostosis, the skull has been shown to be wider at the level of the coronal sutures and shorter at the midsagittal plane. The orbits are smaller, wider spaced, and more protruding, a numerical confirmation of the clinical observations of brachycephaly and exophthalmos.
  • The effect of corrective surgery has been documented. The morphology of the cranial base has been shown to be normalized following cranial expansion surgery in the single-suture and nonsyndromic bilateral coronal synostoses. Also, following successful surgery for Apert syndrome, persistent brachycephalic features are still demonstrated in the form of wide intercoronal distance and short skull anteroposterior length, while the vault remains tall, although the shape of the skull has changed. Following surgery, the brain has been shown to be slow to expand; the new space is mostly occupied by cerebrospinal fluid (CSF), and, often, persistent empty extradural space at the site of frontal advancement remains in the early postoperative period.
• The development of 3D-CT added a new dimension to imaging craniosynostosis. The technique is particularly appropriate for bony structures, and images can demonstrate detailed skull anatomy with a perspective view, which is particularly helpful for understanding complex craniofacial deformities. The skull vault and base deformities can be appreciated in the 3-dimensional space (see Image 5). Features such as a shallow anterior fossa, deformed dystopic orbits, abnormal calvarial contour, and an asymmetric cranial base can all be visualized realistically. This imaging modality has proven valuable for operative planning and assessment of the results of surgery.
• MRI offers improved definition of intracranial soft tissue structures compared with CT scan. Only recently, attention extended beyond the skull bones toward their contents. A wealth of information is gradually emerging. A high incidence of acquired hindbrain herniation has already been shown to occur in children with syndromic craniosynostosis, particularly children with Crouzon and Apert syndrome. Hindbrain herniation has been observed in as many as 70% of these patients (see Image 6). Hindbrain herniation has been demonstrated to be caused by early closure of the lambdoid sutures. Other abnormalities assessed well using MRI are hydrocephalus and cerebral developmental defects, such as myelination defects and deformities of airway pathways, associated with the maxillary hypoplasia seen in Crouzon and Apert syndromes.

TREATMENT

Section 7 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Medical therapy

At some units, patients with positional posterior plagiocephaly, when severe, are treated with plastic caps, which are fitted externally on the head and can gradually manipulate the shape of the skull. No clear benefit has been identified, and they are not always tolerated well. Most cases are mild forms and do not require treatment.

Surgical therapy

Early surgical treatment of craniosynostosis at the end of the 19th century included mostly linear craniectomies and excision of the affected sutures (suturectomies). At the turn of the century, Cushing observed that the complexity of the disorders in patients with craniosynostosis was such that linear craniectomies were hardly addressing the underlying cause. The results of such procedures were unsatisfactory for most types of craniosynostosis, particularly when involving the coronal suture complex. Head shape and exophthalmos did not improve, and further operative treatment was commonly required. For sagittal synostosis, linear craniectomy and excision of the affected suture is still effective when performed in the first few months of life. In older children presenting late with untreated sagittal synostosis, complex cranial vault reconstruction is performed if the severity of the deformity merits treatment.

For other forms of craniosynostosis, involving coronal or metopic sutures, linear craniectomies have been abandoned in favor of more complex cranial expansion and remodeling. The techniques of fronto-orbital advancement were pioneered in Paris in the late 1960s by Tessier and later modified by Marchac. In earlier years, the tendency was for monobloc facial advancement, including the forehead and midface in one osseous block. Monobloc facial advancement procedures have now waned in popularity because they constitute extensive surgery with considerable morbidity and less than superior results.

Most cranial expansion procedures performed in children with craniosynostosis constitute variations of fronto-orbital advancement. The general principle of these procedures is the independent mobilization of the supraorbital bar with a series of facial osteotomies in the appropriate sites of the medial, superior, and lateral orbital walls and the frontal bone. Subsequent advancement and stabilization of the supraorbital bar in a new more anterior position results in expansion of the floor of the anterior fossa and the roof of the orbits. A new forehead is reconstructed with frontal bone flaps designed appropriately. With this technique, the connection of the coronal suture complex with the skull base is disrupted. This standard technique is used for most types of bilateral coronal synostosis, both isolated and syndromic.

Several variations of this technique have been described, differing mainly on the alternative possibilities of fixation of the lateral ends of the supraorbital bar on the adjacent temporal or zygomatic bones. The 2 most frequently used techniques are the "floating forehead" and the "tongue-in-groove" (see Image 7). The former completely disconnects the supraorbital bar and forehead from the temporal bones, with the goal of allowing complete freedom of growth of the forehead from the skull base. The latter purposely attaches the supraorbital bars to the adjacent temporal bones with internal fixation, with the goal of maintaining synchrony of growth between the realigned forehead and the skull base. Although great claims have been made from proponents of both techniques, the clinical results are comparable.

For different types of craniosynostosis, appropriate modifications are made to the main technique of fronto-orbital advancement. In those with metopic synostosis, the ridge of the prematurely fused suture is excised and the forehead is reconstructed with suitably designed frontal flaps and supraorbital bars. In those with unilateral coronal synostosis, earlier views favored unilateral frontal advancement. Although only one coronal suture is prematurely fused, in fact, the deformity is bilateral because the normal side is attempting to compensate; bilateral forehead correction is usually necessary.

All variations of fronto-orbital advancement usually achieve satisfactory cosmetic results, with good forehead appearance and satisfactory cover of the orbits (see Image 8). A problem often encountered and difficult to correct is persistent narrowing in the temporal regions, observed after any type of fronto-orbital advancement. In addition, abnormalities related to abnormal skull growth, such as turricephaly, brachycephaly, low-set ears, and orbital dystopia, usually persist after successful surgery.

Although fronto-orbital advancement provides satisfactory correction of exorbitism and cosmetic improvement of the forehead appearance, the principle of fronto-orbital advancement does not seem to have any scientific basis. Many studies have indicated that this surgical technique is overcorrecting head volume, producing supranormal head volumes. This explains observations of a high incidence of frontal extradural collections at the site of the advancement after a successful surgery. Similarly, following successful correction of unilateral coronal synostosis, the previously compressed brain does not reexpand; instead, cerebrospinal fluid (CSF) occupies the newly created space. In the absence of another, better alternative, fronto-orbital advancement continues to prevail. It appears to have a cosmetic nature in most cases, excluding children with threatening exorbitism.

In a small, selected group of patients, despite classic syndromic appearances, the predominant problem found after careful appraisal of radiologic images is constriction of the posterior aspect of the skull. Recent attention to the posterior skull has demonstrated that posterior skull release can produce satisfactory results, often obviating the need for frontal advancement.

Syndromic patients with midface hypoplasia may require midface advancement later in life, after age 5 years. Midface advancement can be achieved with either a Le Fort III osteotomy and advancement in one operation or midface distraction osteogenesis. The latter is gaining popularity because, although it confines the patient to wearing an external frame for several weeks, it appears to achieve a better, long-lasting result. In the last 5 years, midface distraction has been developed and refined and is regarded as the technique of choice for many patients.

In recent years, the techniques of distraction osteogenesis have also been used in skull vault remodeling in attempts to avoid the extensive surgical procedure of the forehead advancement. This has also been combined with endoscopic techniques. Although these techniques are still in their infancy, they may become more common practice in the next decade as experience is gained and technology and techniques improve.

Genetic treatment of craniosynostosis with cytokines has been proposed, but it is far from becoming everyday clinical practice at present.

Whenever the issue of possible intracranial hypertension arises, ICP monitoring is usually performed over 24 hours using an invasive bolt. Using an invasive bolt requires a small operation. In some units, routine measurement of ICP is performed in all syndromic cases, although this is not a universal policy.

Patients with hindbrain herniation are commonly asymptomatic and do not require surgery, but a small minority may require surgical management if they develop symptoms or syringomyelia (ie, cavitation and CSF collection inside the spinal cord).

Preoperative details

Children with significant midface deformity should be assessed by an anesthetist well before surgery because intubation may be a problem, and, in extreme cases, tracheostomy may be required postoperatively.

Postoperative details

Postoperative imaging is used to demonstrate the new arrangement of the bony architecture of the cranial and facial skeleton. Radiographs obtained early in the postoperative period can be used as references for further assessment. The rate of reossification can be assessed in the regions where dura was left uncovered by calvaria as a result of the advancement.

The evolution of radiological appearances can be particularly useful if the issue of recurrent deformity arises. Although some loss of the advancement is expected in the first few years after operation, other features are also seen in cases of recurrent craniostenosis, such as a localized or generalized copper-beaten appearance and sclerotic hyperdense bands of bone in the calvaria, representing recurrent synostosis.

Recently, the issue of the migration of fixation screws, plates, and wires has gained increasing attention. As the child grows, the skull bones continuously remodel according to natural forces. As a result, the screws used to stabilize the mobilized segment end up buried in the skull or even in the intracranial cavity. Postoperative CT scan images are particularly helpful for monitoring this situation. Although the clinical significance is not known, identification and follow-up of the problem provides an opportunity for appropriate action to be taken. The recent development of bioabsorbable plates and screws may well eradicate the problem of migration.

Follow-up

Typically, each patient has early postoperative plain radiographs, a CT scan in the first few months after operation, and, in syndromic cases, MRI scans at yearly intervals to exclude the development of a hindbrain hernia. In patients with maxillary hypoplasia, yearly plain radiographs may be needed to help assess the progress of the deformity when the issue of possible midface advancement is considered.

COMPLICATIONS

Section 8 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Complications are rare after craniofacial surgery. Hypovolemic shock can occur if significant intraoperative blood loss has not been replaced in a timely manner. Intraoperative dural tears that remain unrecognized can cause postoperative CSF leaks and resultant infection. Epidural or subdural hematoma can occur due to surgical trauma. Almost all patients develop facial swelling postoperatively, more prominent around the eyes, which rarely causes problems. Wound infections are generally rare, even after midface procedures, which, by necessity, involve operating in the oral cavity. The frequency rate of these complications is less than 10%.

ICP bolt insertion has a recognized low complication rate (2%), including intracranial hemorrhage and infection.

OUTCOME AND PROGNOSIS

Section 9 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Most patients respond very well to surgical treatment of craniosynostosis. The improvement in head shape is appreciated almost immediately after the operation. After the first few weeks, the facial swelling and orbital bruising settles, and most parents are happy with the cosmetic result.

In a small minority of patients, the deformity recurs after a few years and requires reoperation.

Children with syndromic deformities require careful follow-up into adulthood because they may develop recurrent stenosis and/or raised ICP from other causes (eg, hydrocephalus, hindbrain hernia). They may need surgery on their midface.

Children with syndromic forms of craniosynostosis (eg, Crouzon or Apert syndrome) can be affected by a variable degree of developmental delay, which becomes apparent later on in life.

FUTURE AND CONTROVERSIES

Section 10 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

With the increasing awareness of pediatricians and family doctors, craniosynostosis is usually diagnosed in the first few months of life. Sagittal synostosis is effectively treated with strip craniectomy when performed in the first 3 months of life. For craniosynostosis affecting the coronal sutures, considerable debate still exists regarding the timing of cranial expansion surgery. Views vary widely. Some physicians prefer to perform surgery soon after birth, while others defer surgery until the child is aged 12 months.

Proponents of early surgery believe that cranial expansion at an early age is taking advantage of the push that the growing brain applies to the skull, while minimizing the risk of mental impairment due to restricted brain growth by relieving intracranial hypertension early. This belief stems from the view that the skull grows in response to the growth of the brain, which is regarded as the main driving force of head growth.

A significant problem associated with early corrective surgery is a higher risk of recurrent deformity. In most series published from centers at which frontal advancement is performed in the first few months of life, a high reoperation rate is reported. This high rate could be explained by the observation that in the first months of life, craniosynostosis is still active; therefore, the effect of cranial expansion is less likely to be retained.

This hypothesis is reflected by the observation that fronto-orbital advancement performed at such an early age needs to include some overcorrection in order to achieve good late results. Often, several operations are required in the first few years of life to achieve satisfactory results. Although this may be socially acceptable among those who seek perfect shape, these procedures constitute major surgery with a small but appreciable risk of morbidity and mortality.

All the published evidence in favor of early surgery is colored by prejudice and preference of the reporting authors, and no comparative study of early versus late surgery has ever been conducted. Some indirect evidence in favor of early surgery has been reported based on measurements of ICP and intelligence quotient. These reports are based on retrospective observations, use very crude measures of outcome, and have not conclusively analyzed the effect of the different variables involved in psychomotor development; therefore, they cannot be regarded as definitive evidence.

Proponents of late surgery believe that delaying surgery until most of the skull growth has been completed reduces the risk for recurrent deformity. This view is supported by an observed lower reoperation rate in children and infants who were initially treated when older than 9 months. Critics of delayed surgical treatment point out that the final results of such policies are often not as attractive cosmetically. In addition, the delay in surgical decompression of the brain may impair the mental and psychological outcome of these children. This may be particularly important because a high proportion of patients with syndromic forms are likely to have intracranial hypertension.

Although significant indirect evidence indicates that late surgery (occurring in children >12 mo) in all types of craniosynostosis, even scaphocephaly, is associated with poor psychomotor development, the issue is complicated by many interrelated parameters and no conclusive evidence has been produced. Conversely, in patients with sagittal synostosis, a 30% incidence of speech and language developmental delay has been observed, which cannot be explained on the basis of sustained intracranial hypertension because the condition is associated with a low incidence of intracranial hypertension and all children undergo the operation early in life.

In attempts to define the optimal surgical time, a few studies have reported measurements of skull volumes in children with craniosynostosis. Some studies concluded that intracranial volume in children with craniosynostosis is within normal limits and that children with Apert syndrome tend to have higher than normal intracranial volumes.

Two studies have attempted to correlate skull volume in craniosynostosis with ICP. No correlation has been identified between ICP and intracranial volume. Intracranial hypertension can exist in the presence of normal head volume. A recent study that analyzed the change of intracranial volume with age showed that patients with craniosynostosis start their life with an intracranial volume smaller than their healthy peers. By the time the infants are aged 6-9 months, their intracranial volume has reached normal levels and continues to grow normally. If any restriction of brain growth by slow skull growth occurs, it is only operative in the first 6 months of life. After the infant is older than 6 months, the effect of craniosynostosis becomes exhausted or burnt out.

The maximum constrictive effect of craniosynostosis appears to occur at birth when the difference in intracranial volume between healthy neonates and neonates with craniosynostosis is maximal. After birth, the constrictive effect gradually declines during the first few months and stops in infants aged 6-9 months. Therefore, this would appear to be the optimal time for definitive corrective surgery because any alteration made on the cranial skeleton is likely to remain. Such a policy would not apply to patients with overriding reasons dictating early operation, such as severe intracranial hypertension or exorbitism.

A major factor implicated in the timing of surgery for craniosynostosis is the development of intracranial hypertension. No reliable indirect indicators exist for intracranial hypertension. Papilledema is rarely seen in children with craniosynostosis, even in the presence of intracranial hypertension. Among patients with verified intracranial hypertension, only a small proportion (16-25%) have papilledema. On the other hand, a late presentation of craniosynostosis can lead to irrecoverable optic atrophy and visual failure due to sustained intracranial hypertension. The presence of a copper-beaten appearance of the skull on the plain skull radiograph does not correlate well with the level of ICP.

No satisfactory noninvasive technique exists for measuring ICP. Previous studies have demonstrated the relative value of transcranial Doppler. The practicalities of performing such an examination are so complex that they prevent the routine use of Doppler in very young patients.

Recent work has indicated that the tympanic membrane could be used for ICP measurement. The current techniques of measuring ICP are invasive, using subdural or intracerebral transducers and having a small but appreciable complication rate.

A significant proportion of patients with craniosynostosis (25-35%) are likely to have intracranial hypertension. The incidence of intracranial hypertension varies among different types of craniosynostosis and is higher in syndromic forms. As many as 60% of patients with Crouzon syndrome and 45% of patients with Apert syndrome have intracranial hypertension. Percentages vary for other forms of craniosynostosis. Of patients with nonsyndromic coronal synostosis, 30% have intracranial hypertension. Of patients with sagittal synostosis, 18% have intracranial hypertension. Of patients with unilateral coronal synostosis, 12% have intracranial hypertension.

ICP has been found at higher rates in children presenting with craniosynostosis when older than 12 months. This may imply a rise in ICP with age in patients with craniosynostosis. Children with late presenting craniosynostosis constitute a rare and poorly studied group in which different considerations may apply with respect to head growth. In addition, intracranial hypertension has been reported to be able to persist despite cranial expansion surgery. This raises the question of whether poor psychomotor development and the high incidence of intracranial hypertension seen in patients with syndromic craniosynostosis could be due to a genetically predetermined tendency for adverse brain development.

The cause and mechanism of intracranial hypertension in children with craniosynostosis is not well understood. Intracranial hypertension may be due to other causes and/or unrelated to skull constriction, such as abnormal venous drainage in the skull base causing venous hypertension, hydrocephalus, and obstruction of the upper airways. The role of venous hypertension has been better appreciated in recent years.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Media file 1:  Skull shape in various forms of craniosynostosis. A is sagittal synostosis, B is metopic synostosis, C is unilateral coronal synostosis, and D is bilateral coronal synostosis.
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Media type:  Image

Media file 2:  Girl aged 11 months with Apert syndrome, with brachycephaly and turricephaly. The low-set ears and flat eyebrows are indicative of the deformed skull base. The maxillary hypoplasia is seen clearly, even at this age, and will become more obvious later on in life.
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Media type:  Photo

Media file 3:  Plain skull radiograph of a child with Apert syndrome (same child as in Image 2). The prominent feature is the bilateral coronal synostosis. The prematurely closed coronal sutures are seen as white sclerotic bands. This resulted in a shallow anterior fossa and shallow orbits.
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Media type:  X-RAY

Media file 4:  CT scan (bone windows) images of a patient with Apert syndrome. The bilateral coronal synostosis has resulted in a shallow anterior fossa, brachycephaly, and increased biparietal distance. The orbits are shallow. The ventricular system has a normal configuration (same patient as in Images 2 and 3).
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Media type:  CT

Media file 5:  Three-dimensional CT scan of a patient with Apert syndrome. The 3-dimensional visualization of the anatomy of the skull offers a more realistic interpretation of the pathological process of craniosynostosis. The anterior fossa is shallow, and the prematurely fused coronal suture is seen as a prominent ridge in the inner surface of the skull. Also, the posterior fossa is shallow. The facial skeleton and the relationship of the facial skeleton with the skull base can also be appreciated (same patient as in Images 2, 3, and 4).
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Media type:  CT

Media file 6:  MRI scan of a patient with Apert syndrome. The abnormal configuration of the brain parenchyma is seen. The multiple-suture synostosis has resulted in oxycephaly, with corresponding distortion of the corpus callosum and the ventricular system. The posterior fossa is shallow and a degree of hindbrain herniation is present (same patient as in Images 2, 3, 4, and 5).
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Media type:  MRI

Media file 7:  Fronto-orbital advancement techniques indicated in any form of bilateral coronal synostosis. On the left, the lines indicate osteotomy sites. The fused coronal sutures are removed (shaded area), and a free supraorbital bar is created and moved forward to enlarge the anterior fossa. The resulting free frontal bone flap is used to reconstruct the forehead, often rotated 180°. In the middle figure, the "floating forehead" technique is shown. The forehead is disconnected from the coronal suture system and the skull base by extending the bone removal in the infratemporal fossa. The supraorbital bar is fixed to the zygomatic bone. On the right, the "tongue-in-groove" technique is shown. The supraorbital bar is fixed to the adjacent temporal bone, in a purposefully created groove, with the goal of minimizing the bone defect under the temporalis muscle.
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Media type:  Image

Media file 8:  Postoperative photograph of a 4-year-old girl with Apert syndrome. She had fronto-orbital advancement when aged 12 months. The orbits are well covered as a result of the advancement, but the ears remain low-set and the turricephaly has not changed significantly. The cosmetic appearance is satisfactory (same patient as Images 2, 3, 4, 5, and 6).
	View Full Size Image
Media type:  Photo

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

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