Scaphocephaly

Sagittal synostosis is the most common form of craniosynostosis. The premature closure of the sagittal synostosis has an estimated prevalence of 2 in 1000 births. Up to 80% of the cases are sporadic, and there is a male-to-female ratio of 3:1 to 4:1.¹ Sporadic cases are mainly related to intrauterine constraint, but some may have a heterogeneous cause. In particular cases, a dominant autosomal inheritance has been described, with 38% penetrance.¹ The frequency of twinning in a series was 4.8%, with only one monozygotic twin pair being concordant for sagittal synostosis.⁴

Histology usually shows synostotic ridging on the posterior part of the fused suture, which is consistent with the sagittal suture being thicker on the ectocranial cortex than on the endocranial side, and the bony edge of the suture becomes progressively thicker from anterior to posterior under normal conditions.⁵ When the sagittal suture is the only involved suture, the head becomes long from front to back (Figs. 65-1 to 65-3). It is narrow from side to side, and frontal compensational bossing may occur when the anterior fontanel is patent. When both fontanels are closed and the posterior part of the suture is predominantly affected, there is a posterior deformity typically referred to as an occipital knob. It is usually accompanied by a thin forehead with severe pterional indentation (leptoscaphocephaly). In the severest forms of scaphocephaly, the head adopts the shape of a saddle, and it is named bathrocephaly. Accurate diagnosis of isolated sagittal synostosis can be made clinically, and operative correction can proceed without a need for radiologic investigations, unless the clinical features are not completely typical.⁶ This could be the case in which Crouzon syndrome in some patients can resemble, early in evolution, an isolated scaphocephaly.

FIGURE 65-1 Scaphocephaly and differential diagnosis. Preoperative three-dimensional reconstructed CT in bird’s eye (A) and lateral (B) views. Preoperative photographs are shown in side and front (C) views. The appearance 2 years after endoscopic correction is seen from front (D) and side (E) views. The patient later developed raised ICP despite excellent aesthetic outcome (frontal view, F; bird’s eye view, G). Genetic studies revealed a mutation in FGFR2, compatible with Crouzon syndrome. CT showed pansynostosis with oxycephaly (not shown). Three-dimensional reconstructed CT after surgical correction is shown in frontal (H) and side (I) views. The patient’s elevated ICP resolved with a favorable outcome.

FIGURE 65-2 Open technique for surgical correction of scaphocephaly in side (A) and bird’s eye (B) views. An S-type incision is seen from a bird’s eye (C) view. Bicoronal modified incision is seen from side (D) and bird’s eye (E) views. A modified prone position allows exposure of entire cranial vault from frontal (F), side (G), and higher-magnification side (H) views. Sagittal suturectomy (I) and osteotomies are seen from side (J) and frontal (K) views. A side (L) view details the lambda and the occipital isle. Postoperative side (M) and bird’s eye (N) images demonstrate correction of scaphocephaly.

FIGURE 65-3 A, Endoscopically assisted surgical correction of scaphocephaly. Patient positioning is seen from side (B) and bird’s eye (C) views. Surgical planning is also seen from side (D) and bird’s eye (E) views. Sagittal suturectomy is seen from a bird’s eye (F) view. Osteotomies are completed, as shown at low (G) and high (H) magnification: Observe emissary veins from the superior sagittal sinus. For patient 1, preoperative images are seen from side (I) and frontal (J) views, and postoperative images are seen from side (K) and frontal (L) views. For patient 2, preoperative side (M) and postoperative side (N) views are shown.

There is a plethora of techniques for the treatment of scaphocephaly^7–11 but most of them include the excision of the sagittal suture with different kinds of parietal and occipital osteotomies with or without frontal osteotomies and remodeling. Surgical correction, whatever the technique, when performed early in infancy, results in satisfactory and persisting reshaping of the skull (Figs. 65-1 to 65-3). Delays in diagnosis, as well as treatment, result in a small subset of patients with uncorrected craniosynostosis that require the development of more extensive calvarial reconstruction techniques (Fig. 65-4). Due to calvarial maturity, these more advanced cases would not be amenable to treatment using less aggressive techniques. After 1 year of age the child’s cranial vault has developed abnormally, resulting in a severe skull base deformity, as shown in the figure. Subsequently, the skull is significantly thicker and less pliable to reshaping. At this age, cranial defects due to aggressive surgical remodeling procedures may not reossify, and there is a lack of the driving mechanism that leads to closure of the sutures. For these patients, an approach with a more comprehensive calvarial reconstruction includes multiple interleaving osteotomies crossing the midline, leading to improvements in biparietal narrowing combined with a bifrontal reconstruction.

FIGURE 65-4 Holocranial dismantling in an older scaphocephaly patient. A, The preoperative side view demonstrates scaphocephaly. Intraoperative bird’s eye (B) and side (C) views demonstrate osteotomies and synostectomy. Postoperative frontal (D), side (E), and bird’s eye (F) views show correction of scaphocephaly.

Trigonocephaly

Trigonocephaly is considered a fairly common type of craniosynostosis. The term was first coined by Welcker in 1862.¹² Formerly denoted as unusual,^12,13 it is now considered to represent about 10% of all patients with deformities related to craniofacial centers^12,14,15 and its frequency is increasing.² Its incidence is estimated to be 1 in 2500 births,¹⁶ and there is a male predominance of 65% to 85%.¹⁴

Closure of the metopic suture starts under normal circumstances at the end of the first year and may last until the end of the second year.¹² When premature suture closure occurs, usually before birth, a typical craniofacial malformation develops. The premature arrest of growth of the metopic suture may present as a spectrum of manifestations, depending on the timing and extent of the suture closure. Its mildest form is a familial and ethnically inherited facial morphology.¹⁷ Milder forms of metopic synostosis consist of only a somewhat prominent metopic ridge that does not need surgical intervention. In severe forms, a characteristic keel-shaped forehead can be observed, with absence of frontal eminences, retruded orbital rims, hypotelorism, and epicanthus giving a peculiar craniofacial appearance to these children. Different degrees of involvement of the anterior chondrocranial structures seem possible, such as presphenoid, mesoethmoid, and ectoethmoid structures.¹⁸ Another explanation for the broad phenotype of affected children could be a nonspecific process acting at different evolutive ages. Trigonocephaly may appear either as an isolated anomaly or as part of syndromes involving prosencephalic or rhinencephalic structures (holoprosencephaly), such as Opitz syndrome,^19,20 Say-Meyer syndrome, or Frydman syndrome.¹² Recently a new fronto-ocular syndrome has been described with trigonocephaly.²¹

Several genetic defects also have been described associated with trigonocephaly. Abnormalities including deletions and duplications of chromosomes 3p, 9p, 1, lq, and 13q have been published.^22–25 Isolated trigonocephaly has an unknown etiology. Autosomal dominant inheritance with very low penetrance has been proposed in 2% to 5% of the cases for familial cases.^15,26 The possible involvement of mutated FGFRs in newborns affected by trigonocephaly has recently been investigated by molecular screening in a search for mutations in FGFR2, which has been implicated in complex craniofacial syndromes. However, none of the cases studied carried mutations, except one that evolved later toward a Crouzon syndrome–like profile.²⁵

Mental delay may occur in isolated trigonocephaly and has been observed in as many as 10% of these children.¹² Development delays may consist of subtle changes in the time of acquisition of head control or sitting position or include more severe forms of mental retardation, with or without intracranial hypertension.

Di Rocco et al. proposed two subgroups on the basis of clinical and radiologic findings.¹⁸ Group I presents with bilateral frontal bone hypoplasia associated with extreme retrusion of the supraorbital margins. In this group, hypotelorism is associated with abnormally deep position of the cribriform plate, giving the ethmoidal region a hollow appearance. In these patients, the nasion–pterional angle is severely restricted and the nasion–clinoidal distance significantly increased. Group II also shows bilateral frontal hypoplasia with hypotelorism, supraorbital retrusion, and a reduced nasopterional angle. However, the nasion–clinoidal distance is almost normal, and pterional evidence is scarcely evident.¹⁸ Moreover, patients in group II showed a lesser degree of temporal compensatory expansion. The authors postulate that in some patients a compensatory elongation of the nasion–clinoidal distance and an incomplete synostosis of the frontoethmoidal sutures allows partial lateral expansion of the anterior cranial fossa, which could diminish the need for posterior calvarial expansion. On the other hand, children with more severe involvement of the nasoethmoidal sutures, resulting in diminished lateral expansion of the anterior fossa, need compensatory changes in the temporal and parietal regions. Patients in group II accomplished good correction of associated hypotelorism, whereas patients in group I did not reach normal interorbital values when treated with the same surgical procedure, which did not include specific treatment of hypotelorism. Other authors have addressed the importance of the moment and degree of involvement of pathologic changes in the anterior chondrocranial structures.^14,27–31 Milder forms of trigonocephaly would affect only the upper metopic suture, whereas more severe forms include involvement of presphenoid, mesoethmoid, and ectoethmoid structures.

Anterior Plagiocephaly

Premature closure of a single coronal suture produces the most complex set of craniofacial deformities due to the peculiarities of the fronto-orbital region and the close relationship between the sutures of the anterior cranial base and the orbits and maxillary complex. The incidence of coronal craniosynostosis has been reported to be variable but can be approximated to be 0.4 per 1000.⁴⁰ Although most cases are sporadic, a familiar incidence of up to 8% in uncomplicated coronal synostosis has been reported.⁴⁰

Frontal or anterior synostotic plagiocephaly has been described in association with unilateral coronal synostosis,^41–44 but it is known to occur with synostosis of other parts of the coronal ring, such as the frontosphenoidal or frontoethmoidal sutures.^41,45–47 In some rare cases, it has been reported to be the result of fusion of the frontosphenoidal⁴⁸ or the frontozygomatic sutures alone.⁴⁹ The deformity is manifest as a progressive cranial, orbital, and facial asymmetry of varying severity, with secondary deformities, considered to be compensatory, existing on the contralateral side (Figs. 65-5 and 65-6). Associated cranial anomalies affect the development of all facial bones and have been referred to as “the most complete presentation of craniofacial asymmetry.”⁵⁰ There is a flat and retruded frontal bone in the affected side with a contralateral bossing. The orbital rim on the synostotic side is also elevated and retruded, while the ipsilateral orbit is elevated and twisted. There is a variable degree of vertical orbital dystopia. The nasal root is deviated toward the closed sutured with an oblique nasal axis. The tip of the nose points to the nonsynostotic side. The zygoma and maxilla are hypoplastic on the affected side, and the ipsilateral temporal bone is malpositioned in an anterior and descended configuration.

FIGURE 65-5 Endoscopically assisted correction of unilateral coronal suture synostosis. A, A preoperative image from a frontal view shows right forehead flattening and superior displacement of the right superior orbital ridge. A preoperative three-dimensional reconstructed CT demonstrates right coronal suture synostosis from frontal (B) and bird’s eye (C) views. D, A postoperative image from a frontal view demonstrates improvement in facial asymmetry. E, A postoperative three-dimensional CT shows improvement in forehead shape and patency of the right coronal suture.

FIGURE 65-6 Standard fronto-orbital reconstruction for correction of unilateral coronal suture synostosis. A, A preoperative image from a frontal view shows right forehead flattening and superior displacement of the right superior orbital ridge. A preoperative three-dimensional reconstructed CT demonstrates right coronal suture synostosis from frontal (B), side (C), and bird’s eye (D) views. E, In comparison, the contralateral coronal suture remains patent. The intraoperative technique is standard fronto-orbital reconstruction, as seen immediately after bony removal (F), during reconstruction (G), and at completion of reconstruction (H). I, A postoperative image is seen from a frontal view at 4 years of age.

Different reconstructive techniques have been described,^{42,43,46,47,50–53} but most of them can be divided between unilateral and bilateral approaches. There is a long-standing controversy on the timing and type of surgical approach. Some authors have advocated early surgery (younger than 6 months),^40,54 whereas others support treating these patients later (between 9 and 10 months).^41,45,51 The former group uses the concept of rapid brain growth leading to advancement of the frontal bones and supraorbital rims.

Proponents of late surgery argue that delayed surgery allows for further maturation and growth of the craniofacial skeleton. There is less reliance on brain growth, and blood loss is better tolerated. Also, there is immediate correction of the deformity. Surgical procedures have expanded from simple suturectomies (Fig. 65-5) to frontal–calvarial vault remodeling consisting of bifrontal craniotomes and orbital frontal bandeau advancement (Fig. 65-6). Aggressive surgical approaches have been supported by the theory of “coronal ring” synostosis, which states that there is an extension of the coronal synostosis into the cranial base.^55,56 However, in most cases of isolated, nonsyndromic, unilateral coronal synostosis, the sphenofrontal, sphenoethmoidal, ethmoidofrontal, and pterional sutures are patent. Furthermore, review of the literature of these patients who have undergone more extensive procedures indicate that the results are inconsistent and mixed. Often, there is restriction of forward anterior skull base growth and advancement, and late correction (older than 9 months) fails to improve vertical dystopia, which persists into adulthood.⁴⁰ Most craniofacial centers use the classic fronto-orbital advancement with unilateral or bilateral correction. Undoubtedly, in cases with severe contralateral compensation (frontal and/or temporal bossing), a bilateral correction is preferred. The correction of orbital dystopia warrants careful preoperative evaluation. Orbital hypoplasia is a consequence of the elevated orbital roofs, frontal development of the greater sphenoidal wings, and descent of the ethmoidal position, secondary to early closure of the coronal sutures. Orbital axes are also altered and point downward and outward. In the severest cases, failure to achieve early treatment or undercorrection may lead to strabismus, amblyopia, and anomalies in the binocular vision.

Multiple Suture Craniosynostosis

Brachycephaly

Brachycephaly is most commonly the result of premature synostosis of both coronal sutures. The anterior fossa adopts a characteristic deformation, and there are retruded frontal bones and orbital rims with a vertical, broad, flat forehead and a high bregmatic point. Brachycephaly may appear as an isolated synostosis and has then a favorable prognosis. Often, it is the common final appearance of different syndromic craniosynostoses that share a premature closure of bicoronal sutures and similar phenotype (e.g., some cases of Saehtre-Chotzen or Pfeiffer type I). For this reason, every patient with brachycephaly should be assessed by a clinical geneticist (Figs. 65-7 and 65-8).

FIGURE 65-7 Occipital advancement by internal distraction in Apert syndrome. A preoperative side view (A) demonstrates the result of underlying pansynostosis, including squamosal region, bicoronal, and occipitotemporal sutures seen on side view three-dimensional reconstructed CT (B). Mandibular internal distraction avoided tracheostomy in this patient with severe mandibular hypoplasia. C, Surgical planning and positioning are prone with a horseshoe headholder and a bicoronal incision. Internal resorbable devices in place during distraction are seen from a side view in the immediate postoperative period (D) and on lateral postoperative x-ray images (E). F, A postoperative side view image shows successful occipital advancement. Fronto-orbital and midface advancement are pending as the next step of treatment.

FIGURE 65-8 Kleeblattschädel deformity in Apert syndrome. Preoperative frontal (A) and side (B) views. Postoperative frontal (C) and side (D) views after occipital expansion (morselization of the parietal–occipital region). Note the improvement in the anterior (fronto-orbital and pterional) after posterior expansion by simply releasing the posterior two thirds of the cranial vault. Comparison of preoperative (E) and postoperative (F) MRI also demonstrates improvement.

Crouzon Syndrome

Crouzon syndrome is an autosomal dominant disorder characterized by craniosynostosis that causes secondary alterations of the facial bones and facial structure. Common features include hypertelorism, exophthalmos and external strabismus, parrot-beaked nose, short upper lip, hypoplastic maxilla, and a relative mandibular prognathism. First described by Crouzon in 1912,⁵⁹ it was not until 1959 that Shiller observed an autosomal dominant transmission.⁶⁰ Crouzon syndrome represents approximately 4.8% of cases of craniosynostosis at birth, and the birth prevalence is estimated to be 16.5 per million births. Crouzon craniofacial dysostosis is linked to a high number of different mutations, but most of them are located on IgIII of FGFR2 (exons 7 and 9) on chromosome 10q. An association between Crouzon syndrome and acanthosis nigricans has been described and is related to an A391E mutation in the FGFR3 gene on chromosome 4p.

Crouzon syndrome is characterized by a premature synostosis of both coronal sutures, with a resultant brachycephalic shape of the skull. Sagittal, metopic, or lambdoid sutures may also be prematurely affected, isolated, or combined (Figs. 65-9 and 65-10). The cranial base and upper facial sutures are involved with a variable degree of midface hypoplasia and malocclusion. The orbits are hypoplastic, and the orbital floor is hollow, resulting in proptosis and additional orbital dystopia that may produce mild to moderate orbital hypertelorism and divergent strabismus. Maxillary hypoplasia results in pseudoprognatism. Nasal septum deviation, together with maxillary hypoplasia, may produce a chronic obstruction to respiratory flow and may be associated with choanal atresia, velopharyngeal incompetence, and relative macroglossia. All of these malformations may lead to severe respiratory obstructions and apneas, which may cause a chronic raised ICP by an increase in venous pressure after hypercapnia and even contribute as an etiopathogenic mechanism in the development of hydrocephalus.

FIGURE 65-9 Fronto-orbital distraction with resorbable devices for anterior advancement. Predistraction frontal (A) and side (B) views show a harmonic Crouzon syndrome patient. In intraoperative frontal (C) and side (D) view images, observe pterional resection and osteotomy lines. E, Intraoperative high magnification of distraction devices. Postoperative frontal (F) and oblique (G) views are shown during distraction. Observe improvement in proptosis. Polysomnography also improved at the end of distraction in this patient with preoperative raised ICP and central apnea.

FIGURE 65-10 Holocranial dismantling in multiple sutures craniosynostosis. For patient 1, multiple suture nonsyndromic synostosis are seen in preoperative oblique frontal (A) and side (B) views and postoperative frontal (C) views. Patient 2 had Crouzon syndrome. Preoperative images are seen in the frontal (D) and side (E) views, as well as preoperative three-dimensional reconstructed CT from frontal (F) and side (G) views and from sagittal view MRI (H). Postoperative frontal (I) and side (J) views of the same patient show marked improvement, as do side views from (K) three-dimensional reconstructed CT and from sagittal MRI (L).

The initial treatment for Crouzon syndrome generally requires cranio-orbital decompression, including bicoronal suture release and osteotomies of the anterior cranial vault and upper orbits with reshaping and advancement. They are usually performed by the age of 8 to 11 months unless signs of increased ICP are found earlier. Sometimes, it is necessary to perform a combined approach, including midface advancement.⁶¹ When Chiari malformation (CM) is identified precociously, an occipital–parietal calvarial decompression may be preferable to achieve a bigger expansion of the intracranial volume, with or without suboccipital decompression.⁶² After proper release of the ICP, fronto-orbital remodeling can be achieved via an anterior approach.

Cloverleaf Skull (Kleeblattschädel)

Kleeblattschädel syndrome is characterized by a trilobar skull caused by frontal and bitemporal bossing. The first description of a trilobar cranial malformation in a newborn was made by Vrolik in 1849,⁷⁷ but the term kleeblattschädel syndrome was not introduced until 1960 by Holtermuller and Wiederman.^77,78 These authors reported a series of children with a trilobar or “cloverleaf” cranium associated with multiple craniosynostoses. In 1965, Commings et al. published the first case in the United States and translated the term kleeblattschädel syndrome into cloverleaf skull.⁷⁸ This malformation has been described in children with Crouzon, Apert, Carpenter, Beare-Stevenson, or type II Pfeiffer syndrome, the latter being most frequently associated (up to 20% in some series).^75,77 The etiology of this syndrome is still unknown and has been attributed to abnormalities of both the calvarium and the skull base, probably due to the presence of a combination of prematurely fused cranial sutures and hydrocephalus.

The surgical management of cloverleaf skull remains one of the most formidable challenges for the craniofacial surgeon (Fig. 65-8). The natural history of this deformity without surgery was well described in the 1960s and 1970s. Just a few of these children survived beyond infancy, and those who did developed severe neurologic deficits. The first attempt at surgical correction was reported by Angle in 1967.⁷⁷ Since then, a number of surgical series have been reported, without a clear conclusion on prognosis and outcome. Review of the literature reveals a lack of consistent surgical strategies.^74–76 Postoperative data are sparse, and reoperation is the rule in these patients, with a consequent increased morbidity. In addition to the significant cosmetic deformity, the constant coexistence of intracranial hypertension, hydrocephalus, hindbrain herniation, severe skull base dysplasia, and anomaly in venous drainage (Fig. 65-11) imposes important neurosurgical considerations throughout treatment.

FIGURE 65-11 Endoscopically assisted surgical correction of trigonocephaly. Preoperative bird’s eye (A) and frontal (B) views. Surgical planning from bird’s eye (C) and oblique (D) views. E, Hairline and eyebrow incisions used for surgical access. Preoperative three-dimensional reconstructed CT from frontal (F) and bird’s eye (G) views. Postoperative three-dimensional reconstructed CT from frontal (H) and bird’s eye (I) views. Patient appearance 1 year after the operation from frontal (J) and side (K) views.

Hydrocephalus in Craniosynostosis

Ventriculomegaly and ventricular asymmetry are frequent even in children with single-suture craniosynostosis, but they require treatment only in selected cases. Abnormal dilatations of the subarachnoid spaces are a common finding and may imply some disturbance in CSF absorption.⁷⁷ In sagittal synostosis, for example, the frequent encasing of the superior sagittal sinus in the bone groove formed by the fused suture may account for some impairment of CSF absorption. This may lead to mild ventricular dilatation and enlarged CSF subarachnoid spaces over the cerebral hemispheres. In comparison, hydrocephalus is a common feature in patients with complex craniosynostosis. Ventricular dilatation has been reported in 30% to 70% of patients with Crouzon and Pfeiffer syndromes and in 40% to 90% of Apert syndrome patients.^66,77,78 With Apert syndrome, most cases of enlarged ventricles remain stable without a shunt, but with Crouzon syndrome and the severest Pfeiffer syndrome cases, shunting is frequently necessary at some stage of treatment. True hydrocephalus has seldom been reported in single-suture pathologies and can almost always be attributed to coincidental disorders independent of craniosynostosis, such as ventricular hemorrhage, meningitis, aqueductal stenosis, or neural tube defects.

Some patients develop rapidly evolving hydrocephalus before any surgical intervention, and this is expected mainly in kleeblattschädel or a severe Pfeiffer condition. In most of the remaining patients, ventricular dilatation only develops following decompressive surgery for craniosynostosis. In these patients, the indication for shunting is mainly based on progressive ventricular dilatation or evidence of persistent intracranial hypertension, which may need to be ascertained by direct pressure monitoring. After cranial surgery, the artificially created spaces are quite often accommodated by some enlargement of the intra- and extracerebral CSF spaces, and the possibility of a compensated or even slowly progressive hydrocephalic state should be taken into account.^77,79

Two combined pathogenic factors have been offered as an explanation for the frequent association of hydrocephalus and complex craniosynostosis: a mechanical increase of the CSF outflow resistance due to constricted growth of the posterior fossa^62,80–82 and an impaired CSF absorption resulting from venous outflow obstruction.^82–84 Crowding of the posterior fossa appears to be an acquired disorder secondary to deficient occipital cranial expansion.^79,85 It has been related to the timing of fusion of the lambdoid suture, which in Crouzon and Pfeiffer syndromes is completed at an earlier age than in Apert syndrome. This would explain the delayed appearance of hydrocephalus in patients with Apert syndrome. The mechanical restriction to CSF outflow would worsen after the development of tonsillar herniation in a small posterior fossa. This theory alone fails to explain the incidence of hydrocephalus, because hindbrain herniation is missing in a number of cases of progressive hydrocephalus.^83,86 And while it is present in many other cases not affected by hydrocephalus, posterior fossa decompression has often failed to sufficiently restore normal CSF circulation.⁸⁰ Therefore, constriction of the posterior fossa may not be a single causative mechanism for hydrocephalus in craniosynostosis.

Venous hypertension has been accepted as another major pathogenic mechanism by several authors, with descriptions of venous sinus hypertension caused by a stenosis of the jugular foramen in hydrocephalic Crouzon syndrome patients.⁸⁴ The venous obstructions could be secondary to the abnormalities of bone growth that affect the base of the skull in children who have craniosynostosis, with early closure of lambdoid and petro-occipital sutures leading to decreased venous outflow through the jugular foramina.⁷⁹ Another possible explanation is that the disordered venous anatomy is primary rather than secondary and results from the same dysplastic processes that affect the cranial vault sutures, the basicranium, and the facial skeleton. The expression of FGFR gene products in the infant craniosynostotic sutures has been described; these products also have been localized by immunohistochemistry to the cranial vascular endothelia of patients with syndromic craniosynostosis.^79,86,87 Therefore, premature endothelial proliferation and subsequent differentiation in the sigmoid and jugular sinuses may result in the narrowed lumen.⁸⁶ Most patients with progressive hydrocephalus simultaneously exhibit signs of venous outflow obstruction and crowded posterior fossa, favoring a combined action of both mechanisms⁷⁷ by assuming that venous hypertension causes a CSF absorption deficit, as well as brain swelling resulting in tonsillar herniation,⁸² or that it aggravates the preexistent cephalocranial disproportion by venous engorgement.^79,81–83

Finally, the contribution of upper airway obstruction to raised ICP has long been recognized; in particular, an increase in ICP during episodes of respiratory obstruction has been documented, as has an improvement in the ophthalmologic signs of increased ICP after nasal airway dilation, nocturnal positive airway pressure, or maxillofacial advancement procedures. Possible underlying mechanisms include carbon dioxide retention during obstructive episodes in nocturnal apneas and cerebral flow changes during active sleep, particularly if they occur in the presence of reduced cerebral compliance.^82,86,88 All of these factors would lead in the end to a venous hypertension that would ultimately interfere with the CSF absorption.

Clinical evaluation is aimed at identifying progressive hydrocephalus. Diagnosis is sometimes difficult, and ventricular dilatation often becomes evident only after decompressive cranial surgery. As in other forms of hydrocephalus, subjective symptoms of intracranial hypertension like headaches, nausea, and vomiting may be missed, mostly in younger patients in whom classic clinical signs may be absent. Papilledema, however, was a rather common sign in my patients, and often the only sign of increased ICP. Mild ventriculomegaly may also exist with intracranial hypertension; therefore, careful monitoring of ICP and ventricular size in the pre- and postoperative period is a mainstay. My department has developed a strict protocol for the follow-up of complex craniosynostosis, which includes close monitoring of these patients with frequent neuroimaging, ophthalmologic survey (funduscopic examination and visual evoked potentials), polysomnography to detect sleep apnea, and invasive monitoring of ICP and cerebral blood flow when necessary to rule out a chronic increase in ICP.

A percentage of craniosynostosis patients goes on to require hydrocephalus treatment.⁷⁹ Improvement of ventricular dilatation has been anecdotally reported following removal of constricting bony ridges or decompressive craniectomies alone.^81,86 Some authors (Genitori, personal communication) have discussed the use of endoscopic third ventriculostomy for selected cases with the rationale that an acquired stenosis of the aqueduct may develop due to periaqueductal compression during progression of the multiple synostoses. In the presence of hindbrain herniation, there is certainly no place for lumbar peritoneal shunts. Therefore, despite other proposed treatment options, ventriculoperitoneal shunting is widely accepted as the most effective treatment for these patients. Overdrainage must be avoided when selecting the shunting system, because it may induce a pseudo–tumor-like state of venous origin, worsening the preexisting venous problem.⁸⁶

When shunting is needed soon after cranial reconstruction, the stability of synostosis surgery may be endangered if the dural envelope does not rapidly expand because of artificial depletion of CSF spaces⁸⁶ and failure of cranial contents to support the bone plates. If shunting is addressed before cranial reconstruction, there is a real possibility of developing new suture closure due to sustained low ICP.

There is little evidence that dilated ventricles per se have an adverse effect on intelligence,^72,77 except that severe congenital hydrocephalus, as observed in the most complex craniofacial syndromes, carries an increased risk of a lower performance level. As in other hydrocephalic states, the prognosis mainly depends on coincidental cerebral abnormalities and on the detrimental effect of long-standing elevated CSF pressure.⁷⁷

Chiari Malformation in Craniosynostosis

The association between CM and premature craniofacial synostosis was first noted by Saldino et al.⁸⁹ in 1972 in one patient with Pfeiffer syndrome. Since then, numerous authors have reported the incidence of chronic tonsillar herniation in multiple suture craniosynostosis,^{62,81,90–92} and it is a frequent finding in syndromic and multisuture craniosynostosis, characterized by early fusion of lambdoid sutures and cranial base synchondroses. The incidence of CM has been reported as high as 70% in Crouzon syndrome,^90,92,94 75% in nonsyndromic oxycephaly,⁹⁵ 50% in Pfeiffer syndrome, and 100% in kleeblattschädel deformity.⁶² CM was found in other types of syndromic craniosynostosis, in some cases of nonsyndromic complex craniosynostosis involving the lambdoid suture, and in some rare cases of scaphocephaly.^85,92

Downward herniation of neural tissue through the foramen magnum is usually an acquired malformation in craniosynostosis and may be secondary to a disproportion between the posterior fossa and the growing hindbrain structures.^96,97 In most cases of craniosynostosis, hindbrain herniation is not present at birth; rather, it develops in response to the changes in the skull base and posterior fossa secondary to premature closure of the lambdoid and cranial base sutures (usually between 3 and 6 months of age), supporting the pathogenetic hypothesis of overcrowding of the posterior fossa secondary to premature suture fusion.^90,97 The excellent review by Cinalli et al. gives a comprehensive overview on the pathogenic mechanisms involved in the development of hindbrain herniation in craniosynostosis.⁹⁷ The progressive fusion of the lambdoid suture produces alteration in the skull base and stenosis of the jugular foramina (if the petro-occipital synchondroses are primarily involved). The first result would be a small posterior fossa, with consequent herniation of the cerebellum into the cervical canal during the phase of rapid neural growth in the first months of life. The second result would be venous hypertension, induced both by jugular foramen stenosis (if the petro-occipital synchondroses are involved) and by crowding of the posterior fossa, with consequent compression of the sigmoid sinus. These factors can obstruct and alter CSF circulation at the level of the posterior fossa and impair CSF reabsorption at the level of the arachnoid granulations, with the overall final result of increased CSF outflow resistance. Severe crowding of the foramen magnum may result not only in hindbrain herniation but also in brain stem compression and deformation of the fourth ventricle. Thus, hindbrain herniation can be considered as a condition creating or aggravating a hydrocephalic state, not a consequence of hydrocephalus. This explains the cases of CM without hydrocephalus that are frequently observed in craniosynostosis without primary involvement of skull base synchondrosis (e.g., oxycephaly) or in the first stages of Crouzon syndrome, where CM is a frequent finding without hydrocephalus.

Under normal conditions, the posterior cranial fossa grows in length in early childhood along the intraoccipital, petro-occipital, and spheno-occipital synchondroses. Growth in the intraoccipital synchondrosis ceases in early childhood, whereas growth in the spheno-occipital synchondrosis continues after puberty.⁹⁸ In syndromic and complex multisutural craniosynostosis, unlike monosutural craniosynostosis, the facial skeleton and the cartilaginous cranial base are primarily involved.⁹⁸ In Crouzon and Apert syndromes, the degree of involvement of the skull base synchondroses and the timing of fusion are different. In Apert syndrome, the spheno-occipital, petro-occipital, and occipital synchondrosis are fused later, beginning after 12 to 48 months of life and ending at the age of 4 years, than in Crouzon syndrome, where they can be completely fused in the first year of life. All this could be conditioned by a different genetic pattern. In syndromic craniosynostosis, the genetic mutations responsible for the disease are located mainly in FGFR1 (Pfeiffer syndrome), FGFR2 (Crouzon, Apert, and Pfeiffer syndromes), and FGFR3 (Crouzon syndrome and acanthosis nigricans). Some authors have suggested a correlation between the mutation observed and the presence or absence of CM.^83,85 In Crouzon syndrome, the patients affected by CM and syringomyelia would present with a variety of mutations that spread over exons IIIa and IIIc of the FGFR2 gene.^92,98 This could explain the significant differences found in the final anatomy of the skull base and the posterior cranial fossa. The Apert basiocciput is larger than normal, whereas in Crouzon syndrome it is smaller.⁹⁹ According to Cinalli et al., Crouzon syndrome patients preferentially expand along a superoinferior axis, whereas little or no growth is allowed along an anteroposterior axis⁹⁷; the foramen and the basion–opisthion area incur only small changes, whereas the more significant alterations are in the cranial base posterior to the foramen.⁹⁹ Previous conditions would result in altered dimensions of the posterior cranial fossa: normal or larger than normal in the Apert syndrome⁹⁹ and smaller, shortened in the anteroposterior axis, and elongated in the superoinferior and lateral axis in Crouzon syndrome.

If the petro-occipital synchondroses are involved, their premature closure may lead to stenosis or atresia of the jugular foramen. Venous hypertension, induced by jugular foramen stenosis,¹⁰⁰ increases the sagittal sinus pressure and results in a higher CSF pressure request to maintain CSF balance. In patients with closed sutures, ICP may rise to very high levels, overcoming the high sagittal sinus pressure and permitting absorption of CSF, with normal-sized or small ventricles, as seen in some cases of pseudotumor cerebri.^83,84 In contrast, in infants and children with open sutures (or following surgical cranial suture release), increased CSF pressure induces progressive head enlargement and dilatation of the ventricles and subarachnoid spaces.^83,84 This is usually followed by the development of collateral venous drainage, through the foramen magnum and/or through emissary veins and scalp veins. This venous pattern highlights a crucial point: In some cases, the main venous drainage occurs through emissary veins rather than through the usual jugular pathway, and the distortion of the previous could lead to a fatal outcome after surgery.¹⁰¹ Enography should form part of the routine magnetic resonance imaging (MRI) protocol for diagnostic assessment of children with complex and syndromic craniosynostosis.¹⁰⁰ Quantification of venous hemodynamics may also have a role, allowing more accurate, noninvasive monitoring of change at follow-up studies.¹⁰²

The rest of the sutures (lambdoid, sagittal, coronal, and metopic) could also play a role in the development of CM. In the setting of in utero closure of sagittal and coronal sutures, a cephalocranial disproportion in the supratentorial compartment occurs early, forcing the neural growth to be directed posteriorly and inferiorly and pushing down the tentorium. This can induce a lower attachment of the tentorium (near the foramen magnum), reducing the size of the posterior fossa and increasing the risk of CM, especially if premature lambdoid synostosis is also involved. The precocity of coronal and sagittal suture synostosis does not seem to play a role in the pathophysiology of CM in Apert (where the sagittal suture is wide open) and Crouzon syndromes. The premature closure of the lambdoid suture reflects the primary closure of the spheno-occipital synchondrosis and could be a reliable radiologic indicator of synostosis of the posterior cranial base sutures. In Crouzon syndrome, the sagittal and lambdoid sutures close early (median 6 and 21 months, respectively), and they close significantly earlier in the cases of Crouzon syndrome associated with CM compared to in Crouzon syndrome patients without CM.⁹⁰ On the contrary, in Apert syndrome, where CM only occurs in approximately 2% to 5% of the cases, the cranial vault synostosis occurs early for the coronal suture (median 5 months) and significantly later for the sagittal and lambdoid sutures (median 51 and 60 months, respectively).

More than one third of patients with hindbrain herniation become symptomatic for CM or develop syringomyelic cavities. Usually, the onset of symptoms occurs late in life, but they may be dramatic—especially in very young children—with appearance of respiratory problems such as central apnea, bilateral vocal cord paralysis, bulbar palsy, ventilatory control abnormalities, persistent cyanosis, and breath-holding spells.⁹⁷ Careful radiologic and clinical follow-up is needed in patients with syndromic or complex craniosynostosis to assess the presence and evolution of CM. MRI with venous angiography is the gold standard for the evaluation of these patients.^100,103

Surgical Techniques

Type I. Endoscopically Assisted Suturectomies and Osteotomies

Different authors have proposed minimally invasive techniques¹⁰⁶ and endoscopic-assisted osteotomies^{9,11,29,40,106} applied to younger patients using the concept of surgically created open sutures that take advantage of the rapid brain growth during the first months of life. Craniectomies and osteotomies (Figs. 65-1, 65-3, 65-5, and 65-12) are designed to mimic new cranial sutures and are followed by active head molding using custom-made helmets. These techniques are used for the treatment of single-suture premature synostosis, although good results have been reported when they are applied to multiple suture synostosis and syndromic involvement.¹³⁶ Small skin incisions (between 1.5 and 2 cm for anterior plagiocephaly and 3.5 and 4 cm for scaphocephaly) are placed over the suture to be resected.

FIGURE 65-12 Three-dimensional CT angiography in cloverleaf deformity. Vascular studies are mandatory in surgical planning before craniotomies in complex craniosynostosis. Observe the vascular draining pattern and relationship between the torcular region and the emissary veins in oblique posterior (A), posterior (B), and bird’s eye (C) views.

In scaphocephaly (Fig. 65-3), the anterior incision is placed 2 cm behind the anterior fontanel, while a posterior incision is over the posterior fontanel. A solution with 0.25% bupivacaine and 1:100,000 epinephrine is injected over the area of dissection. The two small transverse incisions (approximately 2-3 cm length) are lengthened, and a subgaleal plane is developed over the pericranium with the assistance of a rigid endoscope (lens 0 degrees, 2.7 mm) and with electrocautery at a low setting. Bur holes at both sides of the sagittal suture are fashioned at each incision site. The dura is dissected, and bur holes are connected with epidural rongeuring. The sagittal sinus is then separated from the skull using the endoscope, suction, and a Penfield dissector. This moment is particularly helpful in the direct vision of the emissary veins, which can be coagulated with bipolar cautery. Bur holes are longitudinally connected with bone scissors to complete a sagittal suturectomy measuring approximately 3 to 4 cm in width and between 6 and 11 cm in length. The sagittal bone plate is then freed and can be removed. Hemostasis is performed over the bone cuts with tip-insulated electrocautery and with oxidized cellulose and bipolar cautery over the superior sagittal sinus and dura mater. Further dissection is carried out under endoscopic assistance laterally over the parietal areas to achieve wedge osteotomies on both sides, immediately posterior to the coronal suture and immediately anterior to the lambdoid suture, reaching the squamosal sutures. Hemostasis is performed, and resorbable sutures are used for closure. No bandages are needed, and the patient is positioned in a strict supine position during the postoperative stay in the hospital.

For trigonocephaly (Fig. 65-4), the patient is placed supine on a horseshoe headrest. A 2- to 3-cm transverse incision is made just behind the hair line, approximately 3 cm in front of the anterior fontanelle. A subgaleal dissection over the metopic ridge is carried down to the nasion and frontonasal suture with endoscopic assistance and electrocautery. Two bur holes are placed along both sides of the metopic suture at the level of the skin incision and connected crossing the midline. Metopic suturectomy starts posterior to the bregmatic fontanelle. Then, with the aid of the rigid endoscope, epidural dissection under the fused metopic suture proceeds down to the nasofrontal suture. Suturectomy is completed with rongeurs or heavy bone scissors. At this point, some help with a high-speed drill may be needed to cross the thick glabella and may be used for smoothing the frontal bone edges. In some cases, I added frontal oblique-releasing osteotomies. For the severest cases, I advocated a variation of the technique previously published by Cohen et al.¹⁰⁷ The ultimate point of this approach is to achieve a complete fronto-orbitary osteotomy, including both orbital roofs and resection of the entire pterional region, together with metopic suturectomy.

For anterior plagiocephaly (Fig. 65-5), the patient is positioned supine in a neutral position. A 2.5-cm incision is placed halfway along the coronal suture, closer to the bregmatic fontanelle than to the ipsilateral pterion. A dissection plane is carried between the galea and the pericranium with electrocautery, exposing the whole affected coronal suture under endoscopic vision with a rigid lens (0 or 30 degrees). A bur hole is created under the skin incision, and a 1- to 2-cm broad suturectomy is done with rongeurs or bone scissors up to the anterior fontanelle. Then, epidural dissection proceeds downward under endoscopic magnification, exposing the pterion and lesser wing of the sphenoid. Suturectomy is carried out behind the pterional region until the squamosal suture is reached. The osteotomy must be extended down to the pterion and allow the orbit to move forward.^9,40,108 Most patients undergoing endoscopic techniques are later sent for helmet molding therapy.

Type II. Scaphocephaly: Standard Technique

The standard scaphocephaly technique is applied in cases of scaphocephaly in children between 5 and 9 months of age, regardless of the presence of severe compensating frontal bossing (Fig. 65-2). It consists of a sagittal suturectomy with expanding green-stick parietotemporal and occipital osteotomies. The patient is placed in a beanbag horseshoe with the head extended in prone position. A modified retroauricular bicoronal incision (zigzag) is usually preferred for all craniofacial procedures for cosmetic purposes. This approach promotes healing without resulting in wide scars. A subperiosteal dissection separates the calvaria from the coronal sutures to the occipital knob. After sagittal suturectomy, I proceed with biparietal and temporo-occipital wedge osteotomies, expanding the biparietal diameter. In cases of severe occipital prominence, an “island” occipital craniectomy helps correct the posterior deformity (Fig. 65-2L).

Type III. Scaphocephaly: Standard Technique Plus Frontal Remodeling

In children older than 10 months with scaphocephaly and severe anterior bulging, a two thirds anterior cranial vault reconstruction is achieved by obtaining a new frontal bone from a parietal donor site and transposition or remodeling of the former frontal bone by midline split and repositioning. At the same time, bitemporal and parietal osteotomies and subsequent fixation are conducted to expand laterally the pterional indentation.

Type IV. Scaphocephaly: Total Cranial Vault Remodeling (Holocranial Dismantling)

In children older than 12 to 14 months with scaphocephaly, a complete calvarial reconstruction is necessary to achieve an adequate cosmetic result (Fig. 65-4). Severe cranial base distortion and the necessity to change the three diameters (vertical, posterior–anterior, and biparietal) precludes the use of more aggressive techniques that include the dismantling and transposition of multiple bone fragments in the shape of arches (clamshell technique), crosses (holocranial dismantling), or plates and posterior fixation with resorbable material.

Type V. Trigonocephaly: Frontal Remodeling without Fronto-Orbital Bandeau

For patients with trigonocephaly (Fig. 65-13), I routinely use a technique that has been previously reported from my department.^30,31 With the patient in a supine position and through the standard modified retroauricular bicoronal incision, the anterior two thirds of the calvaria; temporal region; both supraorbital margins, including the anterior roof of the orbita; and nasion are exposed subgaleally. A very low bilateral fronto-orbital craniotomy is performed, reaching the frontonasal junction, and pterional regions are rongeured away. Both supraorbital eminences and glabella are then drilled and contoured. Finally, a donor parietal bone is selected with the Marchac template, transposed and fixed with resorbable material.

FIGURE 65-13 Standard fronto-orbital correction for trigonocephaly. A, Preoperative imaging demonstrates bitemporal narrowing and midline forehead ridging. Preoperative three-dimensional CT is seen from frontal (B) and bird’s eye (C) views. Intraoperative images show metopic suture synostosis in situ (D) and after suturectomy (E); frontal (F) and oblique (G) views show detail of cranial vault reconstruction. Postoperative images from frontal (H) and oblique (I) views show correction of trigonocephaly.

Type VI. Anterior Plagiocephaly/Coronal Suture Synostosis: Frontal Remodeling without Fronto-Orbital Bandeau

The same technique of frontal remodeling without fronto-orbital bandeau that is used in trigonocephaly may be used in selected cases of anterior plagiocephaly, assuming that there is no severe orbital dystopia and retrusion of the affected coronal suture. A bifrontal craniotomy is performed to the level of the glabella and supraorbital region. Both pterional regions are thoroughly resected, including the lesser wing of the sphenoid on the affected side. The supraorbital region is then drilled away and contoured. A donor parietal bone is selected with the size and shape appropriate for new fronto-orbital remodeling and fixed with resorbable material. This technique is applied only in cases of plagiocephaly with very mild or no orbital dystopia and symmetric anterior fossa. For the majority of the plagiocephaly cases, a standard fronto-orbital bandeau with the classic tongue-in-groove advance (type VII) is preferable.

Type VII. Anterior Plagiocephaly/Coronal Suture Synostosis: Frontal Bilateral Remodeling with Fronto-Orbital Bandeau

Frontal bilateral remodeling with fronto-orbital bandeau is the technique that I select for most cases of anterior plagiocephaly, where vertical orbital dystopia, short and oblique anterior fossa, and compensating bossing in the contralateral side are consistent findings (Fig. 65-6).

A standard bicoronal approach is achieved with a retroauricular incision and elevation of a bifrontal flap in the loose areolar plane between the periosteum and the galea pericrania. Frontal branches of the facial nerve run inside the external fascia of the temporalis muscle, so care must be taken to not damage them. However, these patients often show low implantation of the temporalis muscle, and dissection under the deep fascia of the muscle opens a broad exposition of the pterion and lateral walls of the orbit. The periosteum is incised at this level, and dissection proceeds in the subperiosteal plane, exposing both the frontal and the pterional areas, the lateral walls of the orbit with partial elevation of the temporalis muscle to expose the greater wing of the sphenoid, and the superior wall of the orbits up to the internal canthus, which is preserved. Before initiating osteotomies, obliquity of the frontal bones, retrusion of the lateral portions of the orbital bandeau, and pterional deformation are assessed. A bifrontal craniotomy is performed after a supraorbital bandeau is created. The marks are extended from the sphenosquamosal suture to its contralateral equivalent prepared for a tongue-in-groove advancement. The bifrontal flap includes the anterior part of the bregmatic fontanelle and both coronal sutures. The anterior fossa is exposed extradurally, with visualization of the anterior two thirds of the orbital roof.

Osteotomies on the orbitofrontal bandeau are now performed, starting on the lateral orbital ridge over the frontozygomatic suture and opening the orbital roof anterior to the cribriform plate at the midline. There is commonly severe sphenoid thickening on the affected side over the pterion, where osteotomies are the last step to obtain a free orbital bandeau. The pterions are then thoroughly resected. The bandeau is anteriorly displaced, with rotation of the lateral extreme of the bandeau projecting forward in the side of synostosis, maintaining the medial aspect of the bandeau in place. The orbital roofs and supraorbital ridge are aligned in proper position, descending the affected side and elevating the nonsynostotic side as needed. Transposed new frontal bone is fixed on the orbital bandeau with absorbable miniplates. Closure proceeds in the standard way, with anterior rotation and elevation of the temporalis muscle bilaterally and covering of the field with the periosteum and the galea. I place two subgaleal drains and close the skin with subcutaneous absorbable sutures and an intradermal suture.

Type VIII. Occipital Remodeling: Occipital Advancement

Single synostosis of the lambdoid suture seldom happens, and surgical indication must be done only in cases of severe cosmetic deformation. In these cases, I performed a bilateral occipital craniotomy with complete posterior remodeling. In younger patients, an endoscopically assisted resection followed by helmet therapy may render good results.¹¹

Posterior occipital advancement, however, is frequently used as the starting procedure for severe craniofacial syndromes, such as Pfeiffer syndrome, Crouzon syndrome, or kleeblattschädel with early elevated ICP when a vault expansion is needed (Fig. 65-7), or in cases of CM associated with multiple craniosynostoses when a single stage procedure for complete calvarial remodeling is not advisable due to elevated venous pressure.⁶² Occipital advancement has been shown to be superior to fronto-orbital advancement in terms of total volume expansion^62,109 and has shown efficacy in correcting the fronto-orbital appearance, even prior to anterior advancement (Fig. 65-8).

Type IX. Standard Bilateral Fronto-Orbital Advancement with Expansive Osteotomies

A standard advancement technique is selected when bilateral anterior fossa advancement and bifrontal remodeling are the goals. The technique consists of standard bilateral fronto-orbital advancement with or without fronto-orbital bandeau plus expansive frontoparietal osteotomies. Characteristically, it allows only a short decrease in the vertical position of the bregma, as the posterior parietal region is not addressed. It is the technique selected in multisutural cases of syndromic (Crouzon, Apert, or Pfeiffer) and nonsyndromic (brachycephaly) involvement of the anterior fossa due to premature fusion of coronal, ethmoidosphenoidal, and frontosphenoidal sutures.

Type X. Holocranial Dismantling (Total Vault Remodeling) in Multiple Craniosynostosis

Holocranial dismantling in multiple craniosynostosis consists of a complete cranial vault remodeling for correction of multiple synostosis to achieve adjustment of the three skull diameters (vertical, interparietal, and posterior–anterior distances) (Fig. 65-10). It can be done in a single surgical step with the patient in a prone position (Persing’s technique)¹¹⁰ or in two steps in the same surgical session (first supine and then prone after closing the bicoronal incision). The two-step variation, commonly used in my department, is preferred over Persing’s technique when venous hypertension, induced both by jugular foramen stenosis and crowding of the posterior fossa with subsequent compression of the sigmoid sinus, makes the hyperextended prone position unadvisable.

With the patient in a supine position, standard bilateral fronto-orbital advancement and frontoparietal remodeling are performed (type IX). A crossbar is designed over the bregmatic region, which allows decrease of the vertical diameter (Fig. 65-10C). After positioning the patient prone, occipital remodeling and advancement are completed (type VIII) (Fig. 65-8). These constitute an extensive procedure with higher morbidity rates that must be reserved for the complex cases in which multiple sutures are involved and early expansion of the whole cranial vault is needed.

Type XI. Fronto-Orbital Advancement by Distraction

The standard fronto-orbital advancement procedure requires elevation of both frontal and orbital bones (Fig. 65-9). This can result in partially resorbed advanced bone and convoluted dura mater that is herniated through the inner table of the skull. If a second operation is performed via the intracranial approach, the dura may be easily torn during calvarectomy and the bone that is advanced can be further resorbed and deformed. Distraction osteogenesis has been used in fronto-orbital advancement for patients with coronal synostosis (nonsyndromic brachycephaly)¹¹¹ or for those patients with a craniofacial syndrome in whom fronto-orbital advancement is needed at any moment. The main advantage of this technique is the possibility to avoid cranial vault defects, because separation between the dura mater and the bone flap is not necessary and therefore deterioration of the dura mater and resorption of the advanced fronto-orbital bone are minimized.^111,112 The concomitant expansion of the scalp prevents postoperative relapse and provides the advancement of soft tissues, thus helping in stability and the final postoperative result. In syndromic patients, “harmonic” Crouzon or Pfeiffer cases (those who present without severe frontal bossing or orbital dystopia) are best candidates. A small but nondisfigured fronto-orbital region may be advanced to avoid intracranial hypertension caused by closure of the anterior cranial fossa and to diminish typical proptosis. The whole fronto-orbital console is advanced to the new position without a change in the shape of the fronto-orbital bandeau. Apert patients usually present with severe retrusion of the supraorbital bar and a large lacunae over the metopic region, which makes them worse candidates for this technique. However, my colleagues and I use it in these patients when preliminary fronto-orbital advancement is needed and a second surgery is planned over the anterior region of the skull. This technique helps us prevent iatrogenic lacunae (Fig. 65-14) and pseudomeningoceles that occur through the standard osteotomies.

FIGURE 65-14 Complications. Craniolacunae are common complications after repeated surgeries (A and B), infection (C and D), or growing fractures (E). They can be treated with customized heterologous implants (F) or, preferably, with autologous bone implants (G-I).

Among its disadvantages are the necessity for a second surgery to remove devices and the inability to reshape deformed fronto-orbital and temporosquamousal bones. For example, the surgeon could not simultaneously reduce an increased bitemporal distance or lower a turricephaly as with the standard techniques. In addition, fronto-orbital advancement by distraction has the disadvantage of technical difficulty in the osteotomy at the anterior cranial base (orbital roof). When the surgical technique is not exquisite, orbital meningoceles resulting from intracranial hypertension have been described.^94,103

The patient is in a supine position under general anesthesia. A zigzag coronal skin incision is made posterior to the planned coronal osteotomy line, and the dissection is performed in a subperiosteal plane down to the supraorbital rims. The anterior one third of the orbital roofs is exposed, carefully preserving the periorbita. The temporalis muscle is detached so that the bur holes can be placed at the middle cranial fossa just behind the sphenoid wing. The osteotomy lines are similar to those of conventional fronto-orbital advancement except for the nonexisting tongue-in-groove osteotomy. Bur holes are placed bilaterally at the pterion just behind the sphenoid wing. Two more bur holes are placed on the glabella at both sides of the end of the superior sagittal sinus. The pterion is then drilled away to expose the anterior fossa behind the wing of the sphenoid and the lateral wall of the orbit anterior to it. The thickened sphenoid ridge is also largely removed. Next, 2- to 3-mm-wide cuts are made in the bone at the lateral and medial orbital rims. The osteotomy is performed to connect the pterional bur holes with the bregma (anterior fontanel) as for standard bifrontal craniotomy. Using a groove director, a Gigli saw is passed from the bur hole at the pterion to the bur holes at the glabella. The Gigli saw is then guided into the cut at the medial orbital rim, and the osteotomy of the anterior cranial base is continued just posterior to the supraorbital rim, joining with the cut at the lateral orbital rim. After the osteotomy is complete, two to four internal distraction devices are placed bilaterally. The detached temporal muscles are sutured back to their original position. Finally, the distraction device rods are allowed to pierce the scalp. I used resorbable distractors to avoid a second operation to remove them. Distraction is initiated on postoperative day 3 or 4 and continued until the desired advancement is achieved. The distraction devices are activated twice daily, moved approximately 0.5 mm per activation, and left in place for an additional 3 weeks. They are then removed through the initial incision, with the patient under sedation, by simply screwing them backward.

Recurrences

As a rule, any craniosynostosis may recur, even after proper treatment, during development. This is particularly true in cases of multiple synostosis and craniofacial syndromes, where the dysplastic processes that affect the cranial vault sutures, the basicranium, and the facial skeleton by the expression of FGFR gene products remain as an underlying condition. This is also a consequence of the cranial base, which remains unchanged despite treatment, because most surgical procedures address the cranial vault but have little effect on the skull base. Recurrences consist mainly of a progressive vault deformation, but the presence of an evolving fracture or the appearance of a new hydrocephalic condition should alert the surgical team to the possibility of unresolved craniosynostosis. Secondary deformations and the appearance or progression of a new suture closure may also indicate overdrainage and a pseudotumor state after shunting in a craniosynostosis patient with hydrocephalus.

Prognosis

Prognosis in craniofacial surgery depends mostly on the underlying condition. The majority of simple craniosynostosis patients with a single affected suture do not develop mental retardation, and surgical treatment on a proper schedule and with the right technique by an experienced team renders good results in terms of cosmetic and functional outcome. Although it has been stressed that the occurrence of raised ICP in single-suture synostosis is low,^109,110,113 up to 15% to 20% of patients with single-suture craniosynostosis have a documented increase in ICP.⁸⁶ This is particularly true in patients with severe trigonocephaly,¹¹⁷ and special attention must be paid to these children. The possibility of elevated ICP is higher as the number of affected sutures increases. The risk is very high in untreated patients with a craniofacial syndrome where craniosynostosis is an evolving condition that worsens during the first years of life and frequently leads to intracranial hypertension. Restricted skull volume contributes to this elevation in ICP, but it is not the only factor responsible. Venous congestion (sometimes with anomalous venous drainage), hydrocephalus, and/or upper airway obstruction are sometimes associated in these patients and are capable of increasing ICP.

Early detection of intracranial hypertension is important to reduce the risks for brain development and visual function. However, in children with craniosynostosis, the clinical manifestations of abnormally increased ICP are difficult to detect, as the majority of patients may have neither warning signs nor symptoms for a long period.⁸⁶ As a result, these children warrant extensive clinical surveillance.

The treatment of complex craniosynostosis and craniofacial syndromes requires the participation and coordination of a multidisciplinary team with profound knowledge of the underlying pathophysiogic mechanisms; the use of multiple diagnostic tools, surgical techniques, and staged approaches; and the management of multiple aspects of patient care. The collaboration of neurosurgeons; syndromologists; pediatricians; plastic and maxillofacial surgeons; ear, nose, and throat surgeons; psychologists; and occupational therapists in a multidisciplinary team is undoubtedly the best approach to treating this pathology. The support provided by specific parental associations with affected children is also a tremendous help for many of these families.

Complications

Mortality rates in craniofacial surgery literature are fortunately very low.^118,119 The most frequent complication in surgical series is postoperative hyperthermia (13.17%), possibly related to more extensive tissue dissection and a higher amount of blood component transfusion, followed by cranial infection (8.2%).⁹⁹ In the series of my department, infection was below 10%.^119–122 We also encountered subgaleal hematomas (6.0%), dural tears (5.1%), and CSF leaks (2.7%) with significantly lower incidence than that given in prior reports.¹²⁰

Several issues have been related to infectious complications: type of craniosynostosis,¹¹⁹ age and surgical timing,¹²⁰ number of surgeons and intensive care unit time,¹²³ and proportion of surgical reoperations.¹²¹ My department found two important factors related not to just infections but to all complications: (1) surgical reoperations and (2) type of surgical procedure.