Introduction
Craniosynostosis involves the premature fusion of one or more cranial sutures. This leads to cranial deformity and potentially raised intra-cranial pressure or other deleterious long-term neurological sequelae.1–3 Synostosis can be ‘simple’, involving only one cranial suture or ‘complex’, involving multiple sutures and/or being related to a genetic syndrome with other limb, neurological, respiratory or cardiac abnormalities. The incidence of craniosynostosis in the population is one in 2000–4000 live births with single suture involvement by far the most prevalent.4,5
The management of craniosynostosis is primarily surgical, however, the timing and choice of surgical intervention varies between units.6–10 There are few high-level evidence studies that compare the different management options for craniosynostoses to support a single model of treatment. Most studies are retrospective, have small cohorts and inconsistently compare outcomes, making comparison of protocols problematic.7,9,11–16 Some studies advocate for early surgical correction of synostosis to improve long-term neurocognitive outcomes whereas other centres perform surgery at a later stage. Moreover, some units propose major surgical procedures such as total calvarial remodeling (TCVR) whereas other units treat similar conditions with minimally invasive techniques, with or without adjuncts, such as cranial springs or helmets.11,17,18 Arguments for delaying operations include: potential for reduced blood product requirement, less disruption to growth and avoidance of deleterious neurocognitive effects of anaesthesia performed at a young age.17,19–24
The aim of this study was to survey paediatric craniomaxillofacial centres in Australia and New Zealand to document current practices with respect to preoperative assessment, surgical management and postoperative follow-up for patients with both syndromic and non-syndromic craniosynostosis.
Methods
Institutional review board approval from Sydney University was obtained (project number 2017/354) to conduct a survey of the assessment and management of craniosynostosis. All members of the Australian and New Zealand Society of Craniomaxillofacial Surgeons (ANZSCMFS) were asked about their usual protocols for the preoperative assessment, intraoperative management and postoperative follow-up of patients with syndromic and non-syndromic craniosynostosis. Specifically, the survey noted which craniofacial multi-disciplinary team members assessed the patients preoperatively, what investigations were performed, the choice and timing of surgical procedures for the different patterns of craniosynostosis and finally, the nature and frequency of follow-up. Surgeons were also surveyed as to what assessments they currently do not perform but would like to in the future. Where there was unclear or missing information provided, surgeons were contacted directly by email to clarify their responses to the survey. Data was collated, de-identified and statistical analysis performed using IBM SPSS Version 25 (SPSS Statistics for Windows, IBM Corp, Armonk, New York, USA, 2017).
Results
All eight centres of craniofacial surgery in Australia and New Zealand who are members of the Australian and New Zealand Society of Craniomaxillofacial Surgeons completed the survey (100% participation).
Single suture craniosynostosis
Preoperative assessment
One centre stated no preoperative investigations were routinely performed, instead being decided on a case-by-case basis. Head circumference was the most uniformly performed preoperative assessment with seven of eight centres using this in single suture synostoses. Computed tomography scanning and fundoscopy were the next most commonly performed assessment, used in six of eight centres. In the instances where preoperative CT scanning was not performed, elevated intracranial pressure was monitored using head circumference and fundoscopy. Where fundoscopy was not performed, CT scanning and head circumference were routine.
Conversely, developmental assessment, sleep studies, MRI and visual evoked potentials (VEPs) were far less common, each being performed in one of eight surveyed centres. Developmental assessment was the most desired service not currently routinely offered for single suture disease within the remaining six of seven centres. Table 1 shows common investigations performed during preoperative assessments and most desired investigations not currently offered.
The management of single suture craniosynostosis across all centres is summarised in Table 2.
Sagittal synostosis management
Management of sagittal synostosis varied with age in six of eight centres. The preferred operation was spring-mediated cranioplasty (SMC) for five centres and total calvarial vault remodelling (TCVR) for the remaining three centres. Centres performing SMC did so at less than six months while TCVR was performed between six–12 months of age. All of the centres preferring SMC performed TCVR for patients presenting after six months of age.
Metopic synostosis management
In seven of eight centres, fronto-orbital advancement remodelling (FOAR) was the preferred procedure. In the remaining centre, SMC performed prior to six months of age is employed. All eight centres performed FOAR for metopic synostosis beyond six months of age.
Lambdoid synostosis management
Spring-mediated cranioplasty is the preferred management at one centre, performed at less than six months of age. TCVR was the next most common procedure, being the preferred intervention at two centres, performed at six–12 months. Lastly, posterior cranial vault remodelling (PCVR) was the most commonly performed procedure, used in five centres. The timing of PCVR varied across these five centres with four operating at or prior to 12 months and one centre after 12 months of age.
Unicoronal synostosis management
Unicoronal synostosis was collectively managed with FOAR or similar operation with patients between six–12 months of age. One centre stated they occasionally performed TCVR in lieu of FOAR in the same age group.
Bicoronal synostosis management
Bicoronal synostosis was managed with a single procedure in six centres, while the remaining two centres used a two-stage surgical approach. Of those performing a single procedure, timing of surgery was between six and 12 months. FOAR was most common, used in five centres. The remaining centre performed SMC. For the two centres who perform two-stage procedure, a posterior vault distraction was performed at six months of age followed by FOAR thereafter at 12 months of age.
Follow-up for single suture craniosynostosis
All centres followed patients annually or bi-annually one year postoperatively. There was some heterogeneity in the length of follow-up with three centres reviewing patients until skeletal maturity, two until teenage years, one until ten years of age, one for five years of age and one centre reviewing patients indefinitely. Table 3 shows common investigations performed at follow-up for single suture craniosynostosis.
Multi suture craniosynostosis
Preoperative assessment
The mean preoperative investigations offered per centre for multi suture craniosynostosis was greater than the mean investigations for simple synostosis (7.50 vs. 4.13, p = 0.003). Head circumference and CT scan are routinely performed preoperatively in all multi suture/syndromic craniosynostosis patients across all eight centres. Three-dimensional photography is routinely offered at four centres with three of the remaining four stating they wish to offer this in the future. Table 4 summarises preoperative assessments for multi suture craniosynostosis.
Management of syndromic craniosynostosis without midface retrusion
In all eight centres, volume expansion of the posterior vault was performed initially. Five centres performed posterior vault distractions, two performed spring-mediated posterior vault cranioplasty and one performed formal posterior vault remodelling. All centres followed expansion of the posterior vault with FOAR with one centre additionally performing tarsorrhaphy. Table 5 summarises the management of multi-suture craniosynostosis syndromic without midface retrusion across eight centres.
Management of syndromic craniosynostosis with midface retrusion
Management of syndromic craniosynostosis with midface retrusion is summarised in Table 6. All eight centres performed an initial procedure to increase the volume of the posterior vault. Five centres performed posterior vault distraction, three performed spring-mediated posterior vault cranioplasy and one performed formal posterior vault remodelling. Subsequent procedures were Le Fort III and monobloc osteotomy in three centres each and FOAR in the remaining two centres. Table 7 shows common follow-up investigations multi suture craniosynostosis.
Discussion
Craniosynostosis may present as simple, single suture disease, involve multiple sutures or be secondary to complex genetic syndromes where multiple sutures and organs are affected. Craniofacial clinics are necessarily multidisciplinary as the management of these patients may be multi-modal. Craniofacial multi-disciplinary teams commonly include neurosurgeons, plastic surgeons, speech therapists, geneticists, ear, nose and throat surgeons, orthodontists, ophthalmologists, sleep physicians, general paediatricians, neuropsychologists and specialist nursing staff.25
This is the first Australasian survey of the preoperative assessment, intraoperative management and postoperative follow-up of patients with craniosynostosis. This is of particular relevance due to the variety of preoperative screening tools and surgical techniques available and the current lack of a definitive management guidelines for any or all variants of craniosynostosis. We demonstrated relative homogeneity of management of the various types of craniosynostosis between surveyed centres with major differences coming in the preoperative screening investigations offered and the management of midface retrusion in syndromic synostosis.
However, the current standard of care and the use of CT scanning for the diagnosis and evaluation of synostosis is controversial. Computed tomography is said to have a role in diagnosis, screening for intracranial complications of craniosynostosis, surgical planning and for use as a baseline for later comparison.26–28 The advent of 3D reconstructions has also added further benefit to diagnosis and preoperative planning.29 Our survey demonstrates that a high proportion of centres across Australia and New Zealand routinely use CT for the preoperative evaluation of patients with single suture craniosynostosis. All centres routinely performed preoperative CT scanning for multi suture and syndromic craniosynostosis.
Whether the detailed information provided by CT scanning is useful in the management of single suture disease is questionable. Some reports suggest clinical examination alone should be sufficient for diagnosis and that the decreased likelihood of intracranial anomalies makes CT less useful in this population.26,30 Some studies have outlined the potential long-term detriments associated with ionising radiation exposure in infancy.31–35 A non-ionising alternative to CT, ‘Black Bone’ MRI, has been shown to accurately identify cranial sutures and diagnose craniosynostosis but lacks widespread availability and would represent a significant pressure on hospital resources.36 Further analysis with multi-centre studies is warranted to ascertain its clinical and cost effectiveness. In our survey, only one centre routinely performed MRI in lieu of CT for single suture craniosynostosis. Magnetic resonance imaging is a safer alternative for young patients and provides greater detail of neuroanatomy to rule out structural brain anomalies. However, CT with 3D reconstructions with its superior bone depiction remains the gold standard imaging technique for craniosynostosis.
Three-dimensional photography is another non-ionising, non-invasive alternative to CT scanning and has been successfully implemented for preoperative phenotype screening, surgical planning and postoperative follow-up to quantify cranial volumes and facial proportions.37–39 Four of the surveyed centres routinely used 3D cameras in the preoperative assessment of both single suture and multi suture/syndromic craniosynostoses. Of the remaining four centres, three stated they wished to offer 3D photography to patients in the future. Sharing of data obtained from 3D cameras would allow for objectively comparing outcomes following synostosis surgery while avoiding the long-term detriments of repeat CT scanning.
Neuropsychology or developmental assessments of patients with synostosis is not routine. However, there is a significant body of evidence that demonstrates significant deficits in memory, language, processing speed and attention in patients with craniosynostosis even with surgical correction.17,40–44 Across Australasia, developmental assessments were offered at two centres for simple, and six centres for multi suture/syndromic synostosis respectively. For the preoperative assessment of simple synostosis, developmental assessment was the most desired service not currently offered.
The management options for sagittal synostosis, the most common type of single suture craniosynostosis, remain broad. Sagittal synostosis was originally treated with simple excision of the fused suture (a sagittal ‘strip’) however, results were inconsistent and the procedure fell out of favour. Some units prefer traditional total calvarial vault remodelling procedures involving the removal of most of the calvarial vault, reshaping and replacing it in order to correct the scaphocephalic head shape.45 Total calvarial vault remodelling is a major surgical undertaking that may involve significant blood loss, long operating time and associated increased hospital length of stay.46 Spring-mediated cranioplasty is a popular alternative to TCVR and, in this study, was used by the most centres for the management of sagittal synostosis. Spring-mediated cranioplasty is usually conducted in patients less than 6–7 months of age with an advantage being that it is minimally invasive and provides active expansion of the cranial vault.47 However, once springs are placed, expansion of the vault cannot be controlled and a second procedure is required to remove the springs. No units in Australasia were using endoscopic suturectomy and helmet therapy to treat craniosynostosis, although this technique is practiced elsewhere.18,48
For other synostoses, our study demonstrated that the vast majority of surveyed centres used FOAR for metopic and unicoronal craniosynostosis and PCVR for the rarer lambdoid synostosis. With fusion of the metopic suture, the sagittal and lambdoid sutures compensate producing increased skull width posteriorly and a narrowed forehead and creating a characteristic triangular appearance when viewed from above.49 In some centres, the management of metopic synostosis is dictated by the severity of disease with mildly affected patients undergoing burring of the affected metopic ridge while more severe cases undergo remodeling.50
In unicoronal synostosis, the ipsilateral forehead flattens, the supraorbital rim is elevated and the contralateral forehead undergoes compensatory bossing.49 Fronto-orbital advancement remodelling is the current standard of care for unilateral coronal synostosis.51
Lambdoid synostosis is rare with the characteristic deformity being an ipsilateral, flat posterior skull with ipsilateral loss of skull height and compensatory parietal bone bossing. In their recent systematic review, Al-Jabri and colleagues showed that an overwhelming majority of published reports on the management of lambdoid synostosis favour more extensive remodelling techniques, similar to the preferences demonstrated across Australasia in this study.8,46,52–59 Some centres however, advocate for minimally invasive strip craniectomy.18
The approach to patients with syndromic multi suture craniosynostosis was relatively consistent between the surveyed centres. Multi-suture syndromic synostosis without midface retrusion was uniformly managed with an initial procedure to increase the volume of the posterior vault, followed by FOAR. Expansion of the posterior vault is considered the ideal first stage procedure in syndromic multi-suture synostoses as it significantly increases intracranial volume and thus reduces the incidence of raised intracranial hypertension and its sequelae.60 An additional advantage of commencing with posterior expansion is that the fronto-orbital region remains untouched, facilitating future monobloc or Le Fort III advancements as appropriate to the case.61
Over 150 syndromes associated with craniosynostosis have been described.49,62 Many of the more common types of syndromic craniosynostoses, such as Crouzon and Apert syndromes, may be associated with significant midfacial hypoplasia, which may be secondary to compensatory growth of the cranium parallel to synostosed sutures and/or a primary developmental abnormality of the cranial base.63–65 The sequelae of the midfacial hypoplasia of syndromic craniosynostosis may include exophthalmos, obstructive sleep apnoea (OSA) and class III malocclusion. Left untreated, exophthalmos may lead to corneal ulceration and visual loss while OSA is associated with daytime somnolence, hypercapnia and raised ICP.63,66–68
The deformity of midfacial hypoplasia in the setting of syndromic craniosynostosis can be addressed in two ways. The first, a two-stage procedure with early fronto-orbital advancement to address brachycephaly and a later Le Fort III advancement to address the midfacial hypoplasia. Alternatively, the forehead and midface can be advanced simultaneously as a ‘monobloc’ or single piece, combining the Le Fort III osteotomy with a frontal bone advancement in patients with severe exophthalmos.49,63,69,70 A perceived advantage of monobloc distraction over Le Fort III is the increased average midface advancement achieved.69 Previous studies have demonstrated improvements in respiratory function, exophthalmos and facial profile with an average of 25 mm advancement, while the average advancement achieved with Le Fort III osteotomies is reportedly in the range of 6–17 mm.66,69,71,72 In the published literature, orbital deficiency (how shallow the syndromic craniosynostosis patient’s hypoplastic orbit lies with resultant exophthalmos) approaches 24 mm.66,69,71,72 While Le Fort III has been successful in expanding orbital cavity volume, monobloc osteotomy may provide an alternative for severe exophthalmos.66
The use of distraction techniques in either Le Fort III or monobloc advancements limits the retrofrontal dead space, allows for brain expansion anteriorly and slow soft tissue accommodation and thus reduces complication rates.61,73 Prior to distraction osteogenesis, midface advancement was performed as a single-stage procedure and was associated with increased rates of haematoma, ascending meningitis and frontal bone loss.62,74 The advent of internal/external distraction allows midface advancement to occur in smaller increments over time and hence may improve the safety of procedure.74,75 Distraction is generally well tolerated, supports newly forming bone and avoids the need for bone grafting.63 However, long term data pertaining to changes in rates of secondary procedures post distraction osteogenesis is lacking and currently, despite best efforts, a large proportion of children with midface hypoplasia will require subsequent operations as they reach adolescence and young adulthood.76 Thus far, it seems morbidity and mortality between patients undergoing Le Fort III or monobloc advancements is similar.69
There are several limitations of this study. Responses may reflect the ideal but not actual management of craniosynostosis at various centres. Moreover, this survey does not account for individual variations in treatment protocols resulting from atypical presentations or individual surgeon preference. For the most desired preoperative investigations, ambiguity exists as to whether or not providing a service represents a limited resource or if centres did not think it indicated. Lastly, this survey is a snapshot into the practices of craniomaxillofacial centres across Australia and New Zealand at this time with trends in patient management not well represented. Future surveys conducted into the management of craniofacial pathologies should include questions on changing or evolving surgical practice as well as rationale for specific investigations and procedures.
Conclusion
This study represents the first attempt to summarise the management of craniosynostosis across a regional program. Despite significant variability in treatment options, the management of synostoses was relatively similar between centres. It is hoped that this work may stimulate collaborative and comparative research between the different units in Australasia.
Acknowledgements
The authors would like to formally acknowledge the support and endorsement of the Australian and New Zealand Society of Craniomaxillofacial Surgeons for this project.
Disclosures
The authors have no conflicts of interest to disclose.
Funding
The authors received no financial support for the research, authorship and/or publication of this article.