Latest trends in minimally invasive synostosis surgery: a review

A preliminary analysis of replicating the biomechanics of helmet therapy for sagittal craniosynostosis

PURPOSE

The aim of this study was to investigate the biomechanics of endoscopically assisted strip craniectomy treatment for the management of sagittal craniosynostosis while undergoing three different durations of postoperative helmet therapy using a computational approach.

METHODS

A previously developed 3D model of a 4-month-old sagittal craniosynostosis patient was used. The strip craniectomy incisions were replicated across the segmented parietal bones. Areas across the calvarial were selected and constrained to represent the helmet placement after surgery. Skull growth was modelled and three variations of helmet therapy were investigated, where the timings of helmet removal alternated between 2, 5, and 8 months after surgery.

RESULTS

The predicted outcomes suggest that the prolonging of helmet placement has perhaps a beneficial impact on the postoperative long-term morphology of the skull. No considerable difference was found on the pattern of contact pressure at the interface of growing intracranial volume and the skull between the considered helmeting durations.

CONCLUSION

Although the validation of these simulations could not be performed, these simulations showed that the duration of helmet therapy after endoscopically assisted strip craniectomy influenced the cephalic index at 36 months. Further studies require to validate these preliminary findings yet this study can lay the foundations for further studies to advance our fundamental understanding of mechanics of helmet therapy.

Impact of age at endoscopic metopic synostosis repair on anthropometric outcomes

OBJECTIVE

Endoscopic strip craniectomy for metopic craniosynostosis relies on rapid growth and postoperative helmeting for correction. Endoscopic repair is generally performed before patients reach 4 months of age, and outcomes in older patients have yet to be quantified. Here, the authors examined a cohort of patients treated with endoscopic repair before or after 4 months of age to determine aesthetic outcomes of delayed repairs.

METHODS

Data from eligible patients were retrospectively assessed and aggregated in a dedicated metopic synostosis database. Inclusion criteria were radiographically confirmed metopic synostosis and endoscopic treatment. Patients were dichotomized into two groups: those younger than 4 months and those 4 months or older at the time of repair. The frontal width and interfrontal divergence angle (IFDA) were measured on reconstructed CT images. These measurements, alongside operative time, estimated blood loss, and transfusion rates, were compared between groups using the Student t-test or chi-square test.

RESULTS

The study population comprised 28 patients treated before 4 months of age and 8 patients treated at 4-6 months of age. Patient sex and perioperative complications did not differ by age group. Older age at repair was not significantly associated with 1-year postoperative IFDA (140° ± 4.2° vs 142° ± 5.0°, p = 0.28) or frontal width (84 ± 5.2 vs 83 ± 4.4 mm, p = 0.47).

CONCLUSIONS

One-year postoperative IFDA and frontal width do not differ significantly between patients treated before and after 4 months of age. Further study with longer follow-up is necessary to confirm the longevity of these results at skeletal maturity.

Endoscopic treatment of sagittal suture synostosis - a critical analysis of current management strategies

While many centers nowadays offer minimally invasive techniques for the treatment of single suture synostosis, surgical techniques and patient management vary significantly. We provide an overview of how scaphocephaly treated with endoscopic techniques is managed in the reported series and analyze the crucial steps that need to be dealt with during the management process. We performed a review of the published literature including all articles that examined sagittal-suture synostosis treated with endoscopic techniques as part of single- or multicenter studies. Fourteen studies reporting results of 885 patients were included. We identified 5 key steps in the management of patients. A total of 188 patients were female and 537 male (sex was only specified in 10 articles, for 725 included patients, respectively). Median age at surgery was between 2.6 and 3.9 months with a total range from 1.5 to 7.0 months. Preoperative diagnostics included clinical and ophthalmologic examinations as well as neuropsychological and genetic consultations if needed. In 5 publications, a CT scan was routinely performed. Several groups used anthropometric measurements, mostly the cephalic index. All groups analyzed equally recommended to perform endoscopically assisted craniosynostosis surgery with postoperative helmet therapy in children < 3 months of age, at least for non-syndromic cases. There exist significant variations in surgical techniques and patient management for children treated endoscopically for single suture sagittal synostosis. This heterogeneity constitutes a major problem in terms of comparability between different strategies.

Ultra-early synostectomy and cranial remodeling orthoses in the management of craniosynostoses

OBJECTIVE

The advent of endoscopic synostectomy has enabled early surgery for infants with craniosynostosis. Even though diagnosis is often made at birth, endoscopic synostectomy has traditionally been delayed until the infant is 3 months of age. There have been very few published reports of this procedure being performed in the early neonatal period. The authors discuss their experience with ultra-early endoscopic synostectomy, defined as an operation for infants aged 8 weeks or younger.

METHODS

A retrospective analysis of infants who underwent operations at or before 8 weeks of age between 2011 and 2020 was done.

RESULTS

Twenty-five infants underwent operations: 11 were 2 weeks of age or younger, 8 were between 3 and 4 weeks of age, and 6 were between 5 and 8 weeks of age. The infants weighed between 2.25 and 4.8 kg. Eighteen had single-suture synostosis, and 7 had multiple sutures involved. Of these 7, 4 had syndromic craniosynostosis. The average operative time was 35 minutes, and it was less than 40 minutes in 19 cases. The estimated operative blood loss was 25 ml or less in 19 cases; 5 infants required an intraoperative blood transfusion. In 1 child with syndromic multisuture craniosynostosis, the surgery was staged due to blood loss. Two children experienced complications related to the procedure: one had an incidental durotomy with skin infection, and the other had postoperative kernicterus. All infants were fitted for cranial remodeling orthoses following surgery. Three of the 25 infants required reoperations, with 2 patients with syndromic craniosynostosis needing repeat surgery for cranial volume expansion and cosmetic appearance. Another child with syndromic craniosynostosis is awaiting cranial expansion surgery. Follow-up varied between 6 months and 8 years.

CONCLUSIONS

The data show that ultra-early synostectomy is safe and not associated with increased complications compared with surgery performed between 3 and 6 months of age. Infants with multisuture synostosis had increased operative time, required blood transfusion, and were more likely to require a second operation.

Spring-Assisted Surgery for Treatment of Sagittal Craniosynostosis

ABSTRACT

Craniosynostosis (CSS), the premature fusion of calvarial sutures, most commonly involves the sagittal suture. Cranial vault remodeling (CVR) is a traditional method of CSS correction. Minimally invasive methods are becoming widely accepted, including spring-assisted surgery (SAS). The equipment required for SAS is minimal therefore adaptable to resource challenged health systems. This paper outlines the experience of SAS in Moldova.A retrospective study was performed for patients treated with SAS for sagittal CSS from 2011 to 2018 in Moldova. Perioperative data were recorded including age, length of surgery, blood loss, volume transfused and length of stay. Four patients had pre- and post-operative computed tomography (CT) scans which were used to calculate changes in cephalic index, normative cephalic index, and intracranial volume.Thirteen patients underwent SAS. Diagnoses were made clinically and confirmed with CT. Mean age at surgery was 4.0 months, and length of surgery 62.7 minutes. All but one patient received a blood transfusion, as is standard of practice in Moldova. The mean length of post-operative recovery in ICU was 30.9 hours. No complications required surgical revision. Springs were removed after 4 to 5 months. All patients had a subjective improvement in scaphocephaly. Based on the available CT scans, an increase in cephalic index (7.3%), normative cephalic index (11.8%), and intracranial volume (38.1%) was observed. One patient underwent SAS at 11 months and required cranioplasty for asymmetry at the time of spring removal.SAS is a safe and cost-effective method of CSS correction that can be utilized in countries with limited health system resources.

A New Technique for Sagittal Synostosis: A Plurality of Small Incisions Minimally Invasive Technique Used on Infants and Young Patients

OBJECTIV

The authors devised a multiple small incisions minimally invasive technique for use in isolated nonsyndromic sagittal synostosis to achieve better esthetic effect and satisfactory reshaping of the calvarial vault. The purpose of this study is to provide clinicians with new and feasible solution.

METHODS

From April 2016 to January 2017, 5 male patients were successfully treated with minimally invasive surgery. The age ranges from 1.5 to 3.3 years. The authors designed 9 short skin linear incisions (2-3 cm long) strategically to disperse in the scalp. The patient was assessed in a series including sex, age of surgery, blood loss, blood transfusion, duration of surgery, postoperative complications, preoperative and postoperative cephalic index (CI), length of stay (LOS), esthetic outcomes, and intellectual developmental quotient (DQ).

RESULTS

The shortest operation time is 1.5 hours. The shortest hospital stay is 6 days. The blood loss ranged from 135 to 280 mL. No serious complications occurred during the follow-up time. Postoperative 3-dimensional CT scan showed that the extensive floating bone formed well. Preoperative CI ranged from 64.2 to 68 and postoperatively 69.4 to 74.3. Mental development was tested by children heath care practioners, significantly improving DQ from 67 to 81 preoperatively and 76 to 90 postoperatively. All children receive good esthetic results.

CONCLUSION

The new technique is safe and effective. The advantages are satisfactory: calvarial fornix remodeling, less visible appearance of scars, shorter length of surgery, lower mental and financial stress, optimal age for surgery, no endoscopic adjuvant and postoperative helmet are needed.

Endoscopy-assisted craniosynostosis surgery followed by helmet therapy

Background

Surgical methods to treat craniosynostosis have evolved from a simple strip craniectomy to a diverse spectrum of partial or complete cranial vault remodeling with excellent results but often with high comorbidity. Therefore, minimal invasive craniosynostosis surgery has been explored in the last few decades. The main goal of minimal invasive craniosynostosis surgery is to reduce the morbidity and invasiveness of classical surgical procedures, with equal long-term results, both functional as well as cosmetic.

Methods

To reach these goals, we adopted endoscopy-assisted craniosynostosis surgery (EACS) supplemented with helmet molding therapy in 2005.

Results

We present in detail our surgical technique used for scaphocephaly, trigonocephaly, plagiocephaly, complex multisutural, and syndromic cases of craniosynostosis.

Conclusions

We conclude that EACS with helmet therapy is a safe and suitable treatment option for any type of craniosynostosis, if performed at an early age, preferably around 3 months of age.

A Systematic Approach to Predicting Spring Force for Sagittal Craniosynostosis Surgery

Spring-assisted surgery (SAS) can effectively treat scaphocephaly by reshaping crania with the appropriate spring force. However, it is difficult to accurately estimate spring force without considering biomechanical properties of tissues. This study presents and validates a reliable system to accurately predict the spring force for sagittal craniosynostosis surgery. The authors randomly chose 23 patients who underwent SAS and had been followed for at least 2 years. An elastic model was designed to characterize the biomechanical behavior of calvarial bone tissue for each individual. After simulating the contact force on accurate position of the skull strip with the springs, the finite element method was applied to calculating the stress of each tissue node based on the elastic model. A support vector regression approach was then used to model the relationships between biomechanical properties generated from spring force, bone thickness, and the change of cephalic index after surgery. Therefore, for a new patient, the optimal spring force can be predicted based on the learned model with virtual spring simulation and dynamic programming approach prior to SAS. Leave-one-out cross-validation was implemented to assess the accuracy of our prediction. As a result, the mean prediction accuracy of this model was 93.35%, demonstrating the great potential of this model as a useful adjunct for preoperative planning tool.

Characterization of complications associated with open and endoscopic craniosynostosis surgery at a single institution

OBJECT The authors present a retrospective cohort study examining complications in patients undergoing surgery for craniosynostosis using both minimally invasive endoscopic and open approaches. METHODS Over the past 10 years, 295 nonsyndromic patients (140 undergoing endoscopic procedures and 155 undergoing open procedures) and 33 syndromic patients (endoscopic procedures in 10 and open procedures in 23) met the authors' criteria. Variables analyzed included age at surgery, presence of a preexisting CSF shunt, skin incision method, estimated blood loss, transfusions of packed red blood cells, use of intravenous steroids or tranexamic acid, intraoperative durotomies, procedure length, and length of hospital stay. Complications were classified as either surgically or medically related. RESULTS In the nonsyndromic endoscopic group, the authors experienced 3 (2.1%) surgical and 5 (3.6%) medical complications. In the nonsyndromic open group, there were 2 (1.3%) surgical and 7 (4.5%) medical complications. Intraoperative durotomies occurred in 5 (3.6%) endoscopic and 12 (7.8%) open cases, were repaired primarily, and did not result in reoperations for CSF leakage. Similar complication rates were seen in syndromic cases. There was no death or permanent morbidity. Additionally, endoscopic procedures were associated with significantly decreased estimated blood loss, transfusions, procedure length, and length of hospital stay compared with open procedures. CONCLUSIONS Rates of intraoperative durotomies and surgical and medical complications were comparable between endoscopic and open techniques. This is the largest direct comparison to date between endoscopic and open interventions for synostosis, and the results are in agreement with previous series that endoscopic surgery confers distinct advantages over open surgery in appropriate patient populations.

Objective classification system for sagittal craniosynostosis based on suture segmentation

PURPOSE

Spring-assisted surgery is an effective and minimally invasive treatment for sagittal craniosynostosis (CSO). The principal barrier to the advancement of spring-assisted surgery is the patient-specific spring selection. The selection of spring force depends on the suture involved, subtypes of sagittal CSO, and age of the infant, among other factors. Clinically, physicians manually judge the subtype of sagittal CSO patients based on their CT image data, which may cause bias from different clinicians. An objective system would be helpful to stratify the sagittal CSO patients and make spring choice less subjective.

METHODS

The authors developed a novel informatics system to automatically segment and characterize sutures and classify sagittal CSO. The proposed system is composed of three phases: preprocessing, sutures segmentation, and classification. First, the three-dimensional (3D) skull was extracted from the CT images and aligned with the symmetry of the cranial vault. Second, a "hemispherical projection" algorithm was developed to transform 3D surface of the skull to a polar two-dimensional plane. Through the transformation, an "effective" projected region can be obtained to enable easy segmentation of sutures. Then, the different types of sutures, such as coronal sutures, lambdoid sutures, sagittal suture, and metopic suture, obtained from the segmented sutures were further identified by a dual-projection technique of the midline of the sutures. Finally, 108 quantified features of sutures were extracted and selected by a proposed multiclass feature scoring system. The sagittal CSO patients were classified into four subtypes: anterior, central, posterior, and complex with the support vector machine approach. Fivefold cross validation (CV) was employed to evaluate the capability of selected features in discriminating the four subtypes in 33 sagittal CSO patients. Receiver operating characteristics (ROC) curves were used to assess the robustness of the developed system.

RESULTS

The segmentation results of the proposed method were clinically acceptable for the qualitative evaluation. For the quantitative evaluation, the fivefold CV accuracy of the classification for the four subtypes was 72.7%. This classification system was reliable with the area under curve (in ROC analysis) being greater than 0.8 for four two-class problems.

CONCLUSIONS

The proposed hemispherical projection algorithm based on backtracking search can successfully segment sutures of the cranial vault. The classification system can also offer a desirable performance. As a result, the proposed segmentation and classification system is expected to bring insights into clinic research and the selection of the spring force to facilitate widespread application of this minimally invasive treatment.

Cranial neural crest cell contribution to craniofacial formation, pathology, and future directions in tissue engineering

This review provides an overview of the state and future directions of development and pathology in the craniofacial complex in the context of Cranial Neural Crest Cells (CNCC). CNCC are a multipotent cell population that is largely responsible for forming the vertebrate head. We focus on findings that have increased the knowledge of gene regulatory networks and molecular mechanisms governing CNCC migration and the participation of these cells in tissue formation. Pathology due to aberrant migration or cell death of CNCC, termed neurocristopathies, is discussed in addition to craniosynostoses. Finally, we discuss tissue engineering applications that take advantage of recent advancements in genome editing and the multipotent nature of CNCC. These applications have relevance to treating diseases due directly to the failure of CNCC, and also in restoring tissues lost due to a variety of reasons.