A review of the management of single-suture craniosynostosis, past, present, and future

A Technique for Minimizing the Need for Hemotransfusion in Non-Syndromic Craniosynostosis Surgery

ABSTRACT

Surgery for craniosynostosis is associated with excessive blood loss, as well as morbidity and mortality risks. This study investigated the effectiveness of a surgical technique for nonsyndromic craniosynostosis intervention in controlling bleeding, assessed based on the volume of blood transfused. The cohort included 73 children who underwent nonsyndromic craniosynostosis surgery during a 3-year period. Retrospective evaluation of patient parameters included sex, weight, and age at the time of surgery; type of craniosynostosis; duration of surgery; hemoglobin concentration before and after surgery; rate of transfusion; and volume of transfused blood (mL/kg). The surgical technique involved skin incision and subgaleal dissection using electrocautery with a Colorado needle tip. The pericranium was not removed but instead kept in situ, and orbiectomy was performed using piezosurgery. Of the 73 children in the cohort, 75.3% underwent fronto-orbital advancement and were included in the analysis. The average age was 10.9 months (range: 4-96 months), with 68.5% boys and 31.5% girls (P < 0.001). The most common type of craniosynostosis was trigonocephaly (57.5%), followed by scaphocephaly (19.2%). The mean duration of the surgery was 2 hours and 55 minutes. Blood transfusion was needed in 56.2% of patients, with a mean volume of 8.7 mL/kg body weight transfused intraoperatively. No complications or fatalities were observed. These results suggested that meticulous, continuous control of homeostasis is paramount in minimizing blood loss during surgical repair of nonsyndromic craniosynostosis.

Endoscopic Spring-Mediated Distraction for Unilambdoid Craniosynostosis

BACKGROUND

Craniosynostosis treatment modalities have changed over time. These have included open calvarial remodeling, suturectomy with helmet molding, hand-powered distraction devices, and spring-mediated distraction. Implantable springs were first described for their use in treatment of craniosynostosis in 1998 (Lauritzen et al, Plast Reconstr Surg 121;2008:545-554). They have been used for the correction of craniosynostosis involving single and multiple sutures and have been placed through both endoscopic and open approaches. Their use for correction of lambdoid synostosis has been previously only described using an open approach (Arnaud et al, Child Nerv Syst 28;2012:1545-1549). The senior author has performed spring-mediated distraction for treating unilambdoid craniosynostosis using an endoscopic approach, which is described below and has not previously been reported by other authors.

METHODS

A retrospective analysis of our series of endoscopic unilambdoid synostosis repairs is included in this article. Patients were analyzed based on patient characteristics, operative details, and outcomes. The operation commences by approaching the lambdoid suture endoscopically through a 2- to 3-cm incision lateral to the lambdoid suture. Burr holes are placed on either side of the suture and a suturectomy is performed. Springs are bent preoperatively to a predetermined force. Two springs are placed across the suturectomy defect and the skin is closed. The patient is monitored for improvement in head shape and cranial X-rays are performed to measure the degree of distraction.

RESULTS

Seven patients underwent endoscopic spring-mediated distraction for unilambdoid craniosynostosis. The average age at the time of operation was 9.4 months. The median force of each spring placed was 7.0 N. The median length of hospital stay after spring placement was 2 days. Springs were removed at 5.6 months on average. Five patients had X-rays immediately after placement and prior to removal. Each spring expanded an average distance of 15.3 mm. There were no surgical complications. Three patients had both preoperative and postoperative computed tomography scans available. The angle of the cranial base, calculated by comparing foramen magnum to cribriform plate angles, improved 5.8° (12.3 preoperatively to 6.6 postoperatively).

CONCLUSION

Endoscopic spring-mediated distraction is a safe and effective method of treatment for unilambdoid craniosynostosis. The series represents the largest experience with this technique. The approach can be considered in all patients with unilambdoid synostosis given the efficacious improvement in vault remodeling, low patient morbidity, short operating time, and minimal inpatient stay.

Gain-of-function variants and overexpression of RUNX2 in patients with nonsyndromic midline craniosynostosis

Craniosynostosis (CS), the premature fusion of one or more cranial sutures, is a relatively common congenital anomaly, occurring in 3-5 per 10,000 live births. Nonsyndromic CS (NCS) accounts for up to 80% of all CS cases, yet the genetic factors contributing to the disorder remain largely unknown. The RUNX2 gene, encoding a transcription factor critical for bone and skull development, is a well known CS candidate gene, as copy number variations of this gene locus have been found in patients with syndromic craniosynostosis. In the present study, we aimed to characterize RUNX2 to better understand its role in the genetic etiology and in the molecular mechanisms underlying midline suture ossification in NCS. We report four nonsynonymous variants, one intronic variant and one 18 bp in-frame deletion in RUNX2 not found in our study control population. Significant difference in allele frequency (AF) for the deletion variant RUNX2 p.Ala84-Ala89del (ClinVar 257,095; dbSNP rs11498192) was observed in our sagittal NCS cohort when compared to the general population (P = 1.28 × 10^-6), suggesting a possible role in the etiology of NCS. Dual-luciferase assays showed that three of four tested RUNX2 variants conferred a gain-of-function effect on RUNX2, further suggesting their putative pathogenicity in the tested NCS cases. Downregulation of RUNX2 expression was observed in prematurely ossified midline sutures. Metopic sites showed significant downregulation of promoter 1-specific isoforms compared to sagittal sites. Suture-derived mesenchymal stromal cells showed an increased expression of RUNX2 over matched unfused suture derived cells. This demonstrates that RUNX2, and particularly the distal promoter 1-isoform group, are overexpressed in the osteogenic precursors within the pathological suture sites.

Epidemiology of craniosynostosis in Norway

OBJECTIVE

The authors present population-based epidemiological data for craniosynostosis regarding incidence, age at diagnosis, sex differences, and frequency of syndromic and familial cases.

METHODS

The prospective registry of the Norwegian National Unit for Craniofacial Surgery was used to retrieve data on all individuals with craniosynostosis treated between 2003 and 2017. The cohort was divided into three 5-year groups based on year of birth: 2003-2007, 2008-2012, and 2013-2017.

RESULTS

The authors identified 386 individuals with craniosynostosis. Of these, 328 (85%) consented to be registered with further information. The incidence increased significantly during the study period and was 5.5 per 10,000 live births (1/1800) in the last 5-year period. The increase was seen almost exclusively in the nonsyndromic group. Syndromic craniosynostosis accounted for 27% of the cases, and the incidence remained stable throughout the three 5-year periods. Both syndromic and nonsyndromic craniosynostosis were highly suture specific. There was a male preponderance (male/female ratio 2:1), and males accounted for 75% of the individuals with midline synostosis. Overall, 9.5% were index individuals in families with more than one affected member; of these, 73% were nonsyndromic cases.

CONCLUSIONS

The incidence of craniosynostosis increased during the study period, and the observed incidence is among the highest reported. The authors attribute this to increasing awareness among healthcare professionals. The number of syndromic cases was high, likely due to a broader definition compared to the majority of earlier reports. The study revealed a high number of familial cases in both syndromic and nonsyndromic craniosynostosis, thus highlighting the importance of genetics as an underlying cause of craniosynostosis.