Comparison of Intracranial Volume and Cephalic Index After Correction of Sagittal Synostosis With Spring-assisted Surgery or Pi-plasty

Springs Produce Favorable Morphologic Outcomes Relative to H-Craniectomy According to a Two-Center Comparison of Matched Cases

BACKGROUND

Sagittal synostosis is the most common type of premature suture closure, and many surgical techniques are used to correct scaphocephalic skull shape. Given the rarity of direct comparisons of different surgical techniques for correcting craniosynostosis, this study compared outcomes of craniotomy combined with springs and H-craniectomy for nonsyndromic sagittal synostosis.

METHODS

Comparisons were performed using available preoperative and postoperative imaging and follow-up data from the 2 craniofacial national referral centers in Sweden, which perform 2 different surgical techniques: craniotomy combined with springs and H-craniectomy (the Renier technique). The study included 23 pairs of patients matched for sex, preoperative cephalic index, and age. Cephalic index, total intracranial volume (ICV), and partial ICV were measured before surgery and at 3 years of age, with volume measurements compared against those of preoperative and postoperative controls. Perioperative data included operation time, blood loss, volume of transfused blood, and length of hospital stay.

RESULTS

Craniotomy combined with springs resulted in less bleeding and lower transfusion rates than H-craniectomy. Although the spring technique requires 2 operations, the mean total operation time was similar for the methods. Of the 3 complications that occurred in the group treated with springs, 2 were spring-related. The compiled analysis of changes in cephalic index and partial volume distribution revealed that craniotomy combined with springs resulted in superior morphologic correction.

CONCLUSION

The findings showed that craniotomy combined with springs normalized cranial morphology to a greater extent than H-craniectomy based on changes in cephalic index and total and partial ICVs over time.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Efficacy and safety of sagittal synostosis surgery in older (> 12 months) patients: a systematic review and meta-analysis

PURPOSE

Sagittal synostosis is the most common isolated craniosynostosis. Surgical treatment of this synostosis has been extensively described in the global literature, with promising outcomes when it is performed in the first 12 months of life. However, in some cases, patients older than 12 months arrive at the craniofacial center with this synostosis. A comprehensive study on efficacy and perioperative outcomes has yet to be fully explored in this population. This systematic review and meta-analysis aimed to assess the available evidence of surgical outcomes for the treatment of sagittal synostosis among older patients to analyze the efficacy and safety of synostosis surgery in this unique population.

METHODS

PubMed, Embase, and Scopus were searched for studies published from inception to March 2024 reporting surgical outcomes of synostosis surgery in older patients (> 12 months) with isolated sagittal synostosis. The main outcome was the reoperation rate, with secondary endpoints including transfusion rates, aesthetic outcomes, and surgical complications.

RESULTS

Nine studies were included in the final analysis. The pooled proportion of the reoperation rate was 1%. The rate of excellent aesthetic results was 95%. The need for transfusion associated with the procedures was 86%, and finally, surgical complications attained a pooled ratio of 2%, indicating minimal morbidity associated with the surgical repair.

CONCLUSION

Sagittal synostosis surgery is a safe and effective procedure to perform in older patients; this meta-analysis suggests that open surgery confers a significant rate of excellent aesthetic results with a low reoperation rate and minimal complications associated with the intervention. Future research with direct comparisons among different techniques will validate the findings of this study, which will all contribute to the rigor of synostosis management.

Craniometric and Aesthetic Outcomes in Craniosynostosis Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically review the published comparative aesthetic outcomes, and its determinants, for craniosynostoses surgically treated by minimally-invasive cranial procedures and open cranial vault remodeling (CVR).

DESIGN

PRISMA-compliant systematic review.

SETTING

Not-applicable.

PATIENTS/PARTICIPANTS

Articles were included if they compared spring cranioplasty, strip minimally-invasive craniectomy or CVR for outcomes related to aesthetics or head shape. Forty-two studies were included, comprising 2402 patients.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

The craniometric and PROM used to determine surgical outcomes.

RESULTS

Twenty-five studies (59%) evaluated sagittal craniosynostosis, with metopic (7;17%) and unicoronal (4;10%) the next most prevalent. Thirty-eight studies (90%) included CVR, 24 (57%) included strip craniectomy with helmeting, 9 (22%) included strip craniectomy without helmeting, 11 (26%) included spring cranioplasty, and 3 (7%) included vault distraction. A majority of studies only used 1 (43%) or 2 (14%) craniometric measures to compare techniques. In sagittal synostosis, 13 (59%) studies showed no difference in craniometric outcomes, 5 (23%) showed better results with CVR, 3 (14%) with strip craniectomy, and 1 (5%) with springs. In studies describing other synostoses, 10/14 (71%) were equivocal. Subjective outcome measures followed similar trends. Meta-analysis shows no significant difference in cranial index (CI) outcomes between CVR and less invasive procedures in patients with sagittal synostosis.

CONCLUSIONS

There is no difference in CI outcomes between CVR and less invasive procedures. The majority of literature comparing craniometric and aesthetic outcomes between CVR and less invasive procedures shows equivocal results for sagittal synostosis. However, the heterogeneity of data for other craniosynostoses did not allow meta-analysis.

Sagittal Craniosynostosis: Comparing Surgical Techniques Using 3D Photogrammetry

BACKGROUND

The aim of this study was to compare three surgical interventions for correction of sagittal synostosis-frontobiparietal remodeling (FBR), extended strip craniotomy (ESC), and spring-assisted correction (SAC)-based on three-dimensional (3D) photogrammetry and operation characteristics.

METHODS

Patients who were born between 1991 and 2019 and diagnosed with nonsyndromic sagittal synostosis who underwent FBR, ESC, or SAC and had at least one postoperative 3D photogrammetry image taken during one of six follow-up appointments until age 6 were considered for this study. Operative characteristics, postoperative complications, reinterventions, and presence of intracranial hypertension were collected. To assess cranial growth, orthogonal cranial slices and 3D photocephalometric measurements were extracted automatically and evaluated from 3D photogrammetry images.

RESULTS

A total of 322 postoperative 3D images from 218 patients were included. After correcting for age and sex, no significant differences were observed in 3D photocephalometric measurements. Mean cranial shapes suggested that postoperative growth and shape gradually normalized with higher occipitofrontal head circumference and intracranial volume values compared with normal values, regardless of type of surgery. Flattening of the vertex seems to persist after surgical correction. The authors' cranial 3D mesh processing tool has been made publicly available as a part of this study.

CONCLUSIONS

The findings suggest that until age 6, there are no significant differences among the FBR, ESC, and SAC in their ability to correct sagittal synostosis with regard to 3D photocephalometric measurements. Therefore, efforts should be made to ensure early diagnosis so that minimally invasive surgery is a viable treatment option.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Three-Dimensional Assessment of Frontal Bossing and Temporal Pinching in Patients with Sagittal Craniosynostosis Using Curvature Analysis

BACKGROUND

Sagittal craniosynostosis results in varying degrees of frontal bossing and bilateral temporal pinching. This study assessed the three-dimensional changes in these regions using curvature analysis and volumetric analysis before and 1 year after extended sagittal strip craniectomy (ESC) with postoperative helmet therapy.

METHODS

A retrospective review of three-dimensional photographs of 50 subjects treated with ESC with postoperative helmet therapy and 50 age-matched controls was performed. Images were collected preoperatively and 1 year postoperatively. Forehead convexity and temple concavity were quantified. Computed tomographic scans of subjects with and without sagittal synostosis were analyzed to assess the percentage of total intracranial volume (ICV) in the anterior cranial fossa before and after ESC with postoperative helmet therapy.

RESULTS

Forehead convexity in the ESC with postoperative helmet therapy group preoperatively (24.49 ± 3.16 m -1 ) was significantly greater than controls (22.48 ± 3.84 m -1 ; P = 0.005). Forehead convexity significantly decreased after ESC with postoperative helmet therapy (18.79 ± 2.43 m -1 ; P < 0.001) and did not differ from controls (19.67 ± 3.08 m -1 ; P = 0.115). The ESC group had more concave temples preoperatively (-10.27 ± 4.37 m -1 ) as compared with controls (-6.99 ± 3.55 m -1 ; P < 0.001). Temple concavity significantly decreased after ESC (-4.82 ± 3.17 m -1 ; P < 0.001) and did not differ from controls (-5.64 ± 3.27 m -1 ; P = 0.075). In the ESC group, the percentage ICV in the anterior cranial fossa decreased from 22.03% to 18.99% after surgery, whereas the anterior volume in controls was stable (17.74% to 16.81%).

CONCLUSIONS

The ESC group had significantly greater forehead convexity, temple concavity and anterior cranial fossa volume compared with controls. One year after ESC with postoperative helmet therapy, forehead convexity, temple concavity, and percentage ICV in the anterior fossa were comparable to controls.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Circulating Brain-Injury Markers After Surgery for Craniosynostosis

OBJECTIVE

Historically, there have been few quantitative methods for effectively evaluating outcomes after surgery for craniosynostosis. In this prospective study, we assessed a novel approach for detecting possible postsurgery brain injury in patients with craniosynostosis.

METHODS

We included consecutive patients operated on for sagittal (pi-plasty or craniotomy combined with springs) or metopic (frontal remodeling) synostosis at the Craniofacial Unit at Sahlgrenska University Hospital, Gothenburg, Sweden, from January 2019 to September 2020. Plasma concentrations of the brain-injury biomarkers neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and tau were measured immediately before induction of anesthesia, immediately before and after surgery, and on the first and the third postoperative days using single-molecule array assays.

RESULTS

Of the 74 patients included, 44 underwent craniotomy combined with springs for sagittal synostosis, 10 underwent pi-plasty for sagittal synostosis, and 20 underwent frontal remodeling for metopic synostosis. Compared with baseline, GFAP level showed a maximal significant increase at day 1 after frontal remodeling for metopic synostosis and pi-plasty (P = 0.0004 and P = 0.003, respectively). By contrast, craniotomy combined with springs for sagittal synostosis showed no increase in GFAP. For neurofilament light, we found a maximal significant increase at day 3 after surgery for all procedures, with significantly higher levels observed after frontal remodeling and pi-plasty compared with craniotomy combined with springs (P < 0.001).

CONCLUSIONS

These represent the first results showing significantly increased plasma levels of brain-injury biomarkers after surgery for craniosynostosis. Furthermore, we found that more extensive cranial vault procedures resulted in higher levels of these biomarkers relative to less extensive procedures.

Introduction of Spring-Assisted Cranioplasty for Sagittal Craniosynostosis in a Craniofacial Service: A Report of Early Experience

Spring-assisted cranioplasty (SAC) for the treatment of craniosynostosis uses internal springs to produce dynamic changes in cranial shape over several months before its removal. The purpose of this study was to report the first Egyptian experiences with SAC in the treatment of children with sagittal synostosis and evaluate the preliminary outcome. A total of 17 consecutive patients with scaphocephaly underwent SAC with a midline osteotomy along the fused sagittal suture and insertion of 3 springs with bayonet-shaped ends across the opened suture. Operative time, blood transfusion requirements and length of ICU, total hospital stay, and complications graded according to Oxford protocol classification were recorded. Spring removal was performed once re-ossification of the cranial defect occurred. All patients successfully underwent SAC without significant complications. The mean age at surgery was 6.8 months. The mean time of the spring insertion surgery was 63 minutes (SD 9.7). Blood transfusion was needed in less than half of the patients (41.2%).The mean duration of hospital stay was 3.2 days. The mean timing of spring removal was 5.5 months (SD 0.4). The mean time of the second surgery (spring removal) was 22.8 minutes (SD 3.6). In conclusion, SAC can easily be incorporated into the treatment armamentarium of craniofacial surgeons. The technique offers a safe and minimally invasive option for the treatment of sagittal craniosynostosis with the benefit of limited dural undermining, minimal blood loss, operative time, anesthetic time, ICU stay, and hospital stay.

A Computational Framework to Predict Calvarial Growth: Optimising Management of Sagittal Craniosynostosis

The neonate skull consists of several bony plates, connected by fibrous soft tissue called sutures. Premature fusion of sutures is a medical condition known as craniosynostosis. Sagittal synostosis, caused by premature fusion of the sagittal suture, is the most common form of this condition. The optimum management of this condition is an ongoing debate in the craniofacial community while aspects of the biomechanics and mechanobiology are not well understood. Here, we describe a computational framework that enables us to predict and compare the calvarial growth following different reconstruction techniques for the management of sagittal synostosis. Our results demonstrate how different reconstruction techniques interact with the increasing intracranial volume. The framework proposed here can be used to inform optimum management of different forms of craniosynostosis, minimising the risk of functional consequences and secondary surgery.

Novel Method of Lateral Vault Modification in Scaphocephaly

BACKGROUND

Scaphocephaly is the commonest from of craniosynostosis. There are several surgical methods to correct this and is influenced by the areas affected. A common thread in any of these corrections is an attempt to increase the biparietal diameter by modifying the lateral vault panel (LVP). A simple and novel method is proposed.

MATERIALS AND METHOD

The records of all patients undergoing scaphocephaly correction in the craniofacial unit at the institution were reviewed from 2003 to 2019. There were 106 patients, 57 males, and 49 females. The age ranged from 6 months to 5 years with a mean of 11 months. The method of vault remodeling was LVP only in 36 (34%), subtotal vault remodeling in 59 (56%), and total vault remodeling in 11 (10%). All 106 patients underwent LVP remodeling as part of the procedure. One or 2 wedge excisions was performed to increase the curvature of the LVP and this panel was fixed on the outside of the temporal squame bone.

RESULTS

The patients were followed up for a minimum of 1 year. Satisfactory results were obtained. The mean preoperative cephalic index was 64% and the mean postoperative index was 75%. There were minor complications such as screw visibility in a few patients.

CONCLUSIONS

Wedge excisions of the LVP is a simple and effective maneuver that can be used as strategy when performing scaphocephaly correction.

Predicting and comparing three corrective techniques for sagittal craniosynostosis

Sagittal synostosis is the most occurring form of craniosynostosis, resulting in calvarial deformation and possible long-term neurocognitive deficits. Several surgical techniques have been developed to correct these issues. Debates as to the most optimal approach are still ongoing. Finite element method is a computational tool that's shown to assist with the management of craniosynostosis. The aim of this study was to compare and predict the outcomes of three reconstruction methods for sagittal craniosynostosis. Here, a generic finite element model was developed based on a patient at 4 months of age and was virtually reconstructed under all three different techniques. Calvarial growth was simulated to predict the skull morphology and the impact of different reconstruction techniques on the brain growth up to 60 months of age. Predicted morphology was then compared with in vivo and literature data. Our results show a promising resemblance to morphological outcomes at follow up. Morphological characteristics between considered techniques were also captured in our predictions. Pressure outcomes across the brain highlight the potential impact that different techniques have on growth. This study lays the foundation for further investigation into additional reconstructive techniques for sagittal synostosis with the long-term vision of optimizing the management of craniosynostosis.

Comparisons of Intracranial Volume and Cephalic Index After Correction of Sagittal Craniosynostosis With Either Two or Three Springs

ABSTRACT

In this retrospective study, the authors determined changes in intracranial volume (ICV) and cephalic index (CI) in patients with sagittal craniosynostosis and operated with craniotomy combined with either 2 or 3 springs. The authors included patients (n = 112) with complete follow-up that had undergone surgical correction for isolated sagittal craniosynostosis with craniotomy combined with springs between 2008 and 2017. All patients underwent computed tomography examination preoperative, at the time of spring extraction, and at 3 years of age. Intracranial volume was measured using a semiautomatic MATLAB program, and CI was calculated as the width/length of the skull. The authors found that craniotomy combined with 2 springs increased the ICV from a preoperative value of 792 ± 113 mL (mean ± standard deviation) to 1298 ± 181 mL at 3 years of age and increased the CI from 72.1 ± 4.1 to 74.6 ± 4.3, whereas craniotomy combined with 3 springs increased the ICV from 779 ± 128 mL to 1283 ± 136 mL and the CI from 70.7 ± 4.3 to 74.8 ± 3.7. The relative increase in ICV was 65 ± 21% in the two-spring group and 68 ± 34% in the three-spring group (P value = 0.559), and the relative increase in CI was 3.6 ± 3.3% in the two-spring group as compared with 6.0 ± 5.0% in the three-spring group (P = 0.004). These findings demonstrated that use of 3 springs resulted in additional absolute and relative CI-specific effects as compared with 2 springs during the time when the springs were in place, with this effect maintained at 3 years of age.

Simplified Postoperative Care After Spring-assisted Strip Craniotomy for Sagittal Synostosis: A Prospective Before-and-After Study

ABSTRACT

Since the development of spring-assisted techniques for corrective craniofacial surgery, routine postoperative admission to intensive care units (ICUs) has been questioned. However, close monitoring is necessary if the continuous infusion of morphine is used as recommended for better pain relief. In this study, the authors evaluated a simplified postoperative protocol without continuous morphine infusion and no indwelling urinary catheter following spring-assisted surgery (SAS) for sagittal synostosis. Ten children were cared for according to a standard protocol with postoperative intravenous (i.v.) infusion of morphine and an indwelling urinary catheter, and 11 consecutive children were treated according to a simplified protocol with pain relief based on intermittent injections of morphine and clonidine [according to Face, Legs, Activity, Cry, Consolability (FLACC) scores >4] without the indwelling catheter. A Mann-Whitney U test was used for comparison of distributions between the two groups. The results revealed no differences between groups regarding the proportion of FLACC scores >4, total amount of administered i.v. morphine and clonidine, total volume of buffered glucose infused, time to first feeding on breast milk or substitute, or the length of stay. Despite the inherent limitations of our small observational study, the authors concluded that at our institution, it was possible to exclude a standard continuous i.v. infusion of morphine and an indwelling urinary catheter from our postoperative care protocol without decreasing the quality of pain relief in children submitted to SAS for sagittal synostosis. This finding supports downgrading the level of care from the ICU to a regular ward after limited immediate postoperative observation.

Comparison of 2 Sagittal Craniosynostosis Repair Techniques: Spring-Assisted Surgery Versus Endoscope-Assisted Craniectomy With Helmet Molding Therapy

INTRODUCTION

This study compares anthropometric outcomes of 2 sagittal synostosis repair techniques: spring-assisted surgery and endoscope-assisted craniectomy with molding helmet therapy.

METHODS

Patients undergoing spring-assisted surgery (n = 27) or endoscope-assisted craniectomy with helmet therapy (n = 40) at separate institutions were retrospectively reviewed. Pre- and 1-year postoperative computed tomography (CT) or laser scans were analyzed for traditional cranial index (CI), adjusted cranial index (aCI), and cranial vault volume (CVV). Nine patient-matched scans were analyzed for measurement consistency.

RESULTS

The spring-assisted group was older at both time points (P < .050) and spring-assisted group CVV was larger preoperatively and postoperatively (P < .01). However, the change in CVV did not differ between the groups (P = .210). There was no difference in preoperative CI (helmet vs spring: 70.1 vs 71.2, P = .368) between the groups. Postoperatively, helmet group CI (77.0 vs 74.3, P = .008) was greater. The helmet group also demonstrated a greater increase in CI (6.9 vs 3.1, P < .001). The proportion of patients achieving CI of 75 or greater was not significantly different between the groups (helmet vs spring: CI, 65% vs 52%, P = .370). There was no detectable bias in CI between matched CT and laser scans. Differences were identified between scan types in aCI and CVV measurements; subsequent analyses used corrected CVV and aCI measures for laser scan measures.

CONCLUSIONS

Both techniques had equivalent proportions of patients achieving normal CI, comparable effects on cranial volume, and similar operative characteristics. The study suggests that there may be greater improvement in CI in the helmet group. However, further research should be performed.

Secondary Coronal Synostosis After Early Surgery for Sagittal Craniosynostosis: Implications for Cranial Growth

ABSTRACT

Secondary Coronal Synostosis (SCS) in patients operated for non-syndromic Sagittal Craniosynostosis is a postoperative phenomenon with unclear implications. The aim of this study was to investigate whether SCS is a negative or a benign occurrence in the postoperative course. The authors hypothesized that SCS is related to reduced cranial growth and intracranial hypertension. Thirty-one patients operated for SC at an early age with the H-craniectomy technique were included in the study. Associations between SCS and cranial shape, growth, and signs of intracranial hypertension were analyzed. Intracranial volume distribution was assessed by measuring partial intracranial volumes defined by skull base landmarks. A total of 12/31 patients developed SCS during the postoperative course. The presence of SCS was associated with a higher prevalence of gyral impressions and a larger normalization of Cranial Index due to less growth in the anteroposterior plane. The SCS group had a smaller postoperative intracranial volume due to less posterior intracranial volume as well as less growth in head circumference. Whether this is a growth restriction caused by the SCS or a secondary effect of less primary brain growth remains to be determined. However, the correlation between SCS, less cranial growth and gyral impressions does imply that SCS should be taken into consideration during clinical follow-up as a potentially adverse event.

Cranial growth in isolated sagittal craniosynostosis compared with normal growth in the first 6 months of age

Sagittal craniosynostosis (SCS), the most common type of premature perinatal cranial suture fusion, results in abnormal head shape that requires extensive surgery to correct. It is important to find objective and repeatable measures of severity and surgical outcome to examine the effect of timing and technique on different SCS surgeries. The purpose of this study was to develop statistical models of infant (0-6 months old) skull growth in both normative and SCS subjects (prior to surgery). Our goal was to apply these models to the assessment of differences between these two groups in overall post-natal growth patterns and sutural growth rates as a first step to develop methods for predictive models of surgical outcome. We identified 81 patients with isolated, non-syndromic SCS from Seattle Children's Craniofacial Center patient database who had a preoperative CT exam before the age of 6 months. As a control group, we identified 117 CT exams without any craniofacial abnormalities or bone fractures in the same age group. We first created population-level templates from the CT images of the SCS and normal groups. All CT images from both groups, as well as the canonical templates of both cohorts, were annotated with anatomical landmarks, which were used in a growth model that predicted the locations of these landmarks at a given age based on each population. Using the template images and the landmark positions predicted by the growth models, we created 3D meshes for each week of age up to 6 months for both populations. To analyze the growth patterns at the suture sites, we annotated both templates with additional semi-landmarks equally spaced along the metopic, coronal, sagittal and lambdoidal cranial sutures. By transferring these semi-landmarks to meshes produced from the growth model, we measured the displacement of the bone borders and suture closure rates. We found that the growth at the metopic and coronal sutures were more rapid in the SCS cohort than in the normal cohort. The antero-posterior displacement of the semi-landmarks also indicated a more rapid growth in the sagittal plane in the SCS model than in the normal model. Statistical templates and geometric morphometrics are promising tools for understanding the growth patterns in normal and synostotic populations and to produce objective and reproducible measurements of severity and outcome. Our study is the first of its kind to quantify the bone growth for the first 6 months of life in both normal and sagittal synostosis patients.

Quantitative evaluation of local head malformations from three-dimensional photography: application to craniosynostosis

The evaluation of head malformations plays an essential role in the early diagnosis, the decision to perform surgery and the assessment of the surgical outcome of patients with craniosynostosis. Clinicians rely on two metrics to evaluate the head shape: head circumference (HC) and cephalic index (CI). However, they present a high inter-observer variability and they do not take into account the location of the head abnormalities. In this study, we present an automated framework to objectively quantify the head malformations, HC, and CI from three-dimensional (3D) photography, a radiation-free, fast and non-invasive imaging modality. Our method automatically extracts the head shape using a set of landmarks identified by registering the head surface of a patient to a reference template in which the position of the landmarks is known. Then, we quantify head malformations as the local distances between the patient's head and its closest normal from a normative statistical head shape multi-atlas. We calculated cranial malformations, HC, and CI for 28 patients with craniosynostosis, and we compared them with those computed from the normative population. Malformation differences between the two populations were statistically significant (p<0.05) at the head regions with abnormal development due to suture fusion. We also trained a support vector machine classifier using the malformations calculated and we obtained an improved accuracy of 91.03% in the detection of craniosynostosis, compared to 78.21% obtained with HC or CI. This method has the potential to assist in the longitudinal evaluation of cranial malformations after surgical treatment of craniosynostosis.

The value of three-dimensional photogrammetry in isolated sagittal synostosis: Impact of age and surgical technique on intracranial volume and cephalic index─a retrospective cohort study

PURPOSE

The aim of this study was to compare the outcome of intracranial volume (ICV) and cephalic index (CI) between two different techniques for surgical therapy of sagittal synostosis.

MATERIAL AND METHODS

Between 2011 and 2015, all patients scheduled for surgical therapy of sagittal synostosis were consecutively enrolled. All patients younger than 6 months underwent early extended strip craniectomy (ESC group), and patients older than 6 months underwent late modified pi-procedure (MPP group). To measure ICV and CI, data acquisition was performed via three-dimensional photogrammetry, 1 day before (T0) and between 10 and 12 weeks after surgery (T1). Results were compared with an age-matched reference group of healthy children. Perioperative parameters, as duration of surgery and the amount of blood loss of both surgical procedures were analyzed.

RESULTS

A total of 85 patients were enrolled. Of the patients, 48 underwent an extended strip craniotomy with parietal osteotomies and biparietal widening and 37 patients underwent a late modified pi-procedure. There was no significant difference between the ESC group and the MPP group regarding the efficacy of improving CI (p > 0.05). Both techniques were able to normalize CI and to improve head shape. ICV was normal compared to age-matched norm-groups with both techniques, pre- and postoperatively. However, duration of the surgical procedure and calculated blood loss were significantly lower in the ESC group (p < 0.05).

CONCLUSION

ESC and MPP were effective techniques to normalize cephalic index (CI) and improve head shape at their recommended time of surgery. Measurement of ICV and CI with 3D photogrammetry is a valid method to objectively evaluate patients before and after surgery without exposing pediatric patients to ionizing radiation.

Cranial bone structure in children with sagittal craniosynostosis: Relationship with surgical outcomes

BACKGROUND

While spring-assisted cranioplasty has become a widespread technique to correct scaphocephaly in children with sagittal synostosis, predicting head shape changes induced by the gradual opening of the springs remains challenging. This study aimed to explore the role of cranial bone structure on surgical outcomes.

METHODS

Patients with isolated sagittal synostosis undergoing spring-assisted cranioplasty at GOSH (London, UK) were recruited (n = 18, age: 3-8 months). Surgical outcome was assessed by the change in cephalic index measured on 3D head scans acquired before spring insertion and after their removal using a 3D handheld scanner. Parietal bone samples routinely discarded during spring-assisted cranioplasty were collected and scanned using micro-computed tomography. From visual assessment of such scans, bone structure was classified into one- or three-layered, the latter indicating the existence of a diploë cavity. Bone average thickness, volume fraction and surface density were computed and correlated with changes in cephalic index.

RESULTS

Cephalic index increased for all patients (p < 0.001), but individual improvement varied. Although the patient age and treatment duration were not significantly correlated with changes in cephalic index, bone structural parameters were. The increase of cephalic index was smaller with increasing bone thickness (Pearson's r = -0.79, p < 0.001) and decreasing bone surface density (r = 0.77, p < 0.001), associated with the three-layered bone structure.

CONCLUSIONS

Variation in parietal bone micro-structure was associated with the magnitude of head shape changes induced by spring-assisted cranioplasty. This suggests that bone structure analysis could be a valuable adjunct in designing surgical strategies that yield optimal patient-specific outcomes.