Introduction:
Isolated sagittal craniosynostosis (ISS) is a congenital cranial anomaly, that results in a characteristic scaphocephalic deformity of the head. It is characterized by a biparietal narrowing of the head and a frontal and occipital bossing. The treatment is exclusively surgical. One of the most established surgical techniques is the Renier 'H' technique (RHT), in which biparietal releasing osteotomies are performed. A more extensive surgical technique is the so-called total vault remodeling (TVR), in which also the frontal bone is actively reshaped.
The evaluation of the esthetical outcome of surgical treatment of ISS is difficult and is based on the subjective judgment of the examinator. Alternatively, craniometric measurements can be performed based on the use of calipers or on 3D images, which can be done by means of computerized tomography or 3D stereophotogrammetry.
3D stereophotogrammetry is a fast, low-cost and accurate technique for obtaining three-dimensional images without exposing children to ionizing radiation and general anesthesia. 3D stereophotogrammetry can be used to assess preoperative head deformity and for postoperative follow-up.
Methods:
The study was retrospective. Measurements were performed in two groups of children: one group of children after RHT and one group of children after TVR. These two groups were compared with a third group of normocephalic children without ISS. Children who underwent surgery for ISS between April 2015 and September 2020 and who were between 12 and 24 months of age at the time of surgery, were included. All children had 3D stereophotogrammetric scanning performed between the first and second year of age and at least three months after surgery. On the 3D images we marked the two tragus (T), the nasion (N), the point between the two tragus (M), the plane between the points T-N-T (plane-0) and the point on the vertex (V). The plane-0 was shifted up to the junction with the opisthocranion. In this plane, which is the most sensitive to the characteristic frontal and occipital bossing, we measured the cranial index (CI). In addition to the CI, we also measured the sagittal circumference, coronal circumference, coronal-sagittal index (CSI: coronal length/sagittal lenght), coronal circumferential index (CCI: distance T-T/coronal length) and vertex height index (VHI: distance T-T/distance M-V).
Results:
Each of the three groups (RHT, TVR, control group) included 28 children. Six measurements were performed on each 3D image. The statistical analysis showed a statistically significant difference between the two groups of operated children for CI (p=0.011) and for sagittal circumference (p=0.008). Both metrics evaluated frontal convexity and their values were closer to normocephaly after the PCS procedure, in which the frontal bone was reshaped, compared to the RHT procedure. Non-significant statistical differences were demonstrated for the measures evaluating biparietal extension after both procedures, respectively for CSI (p=0.649), CCI (p=1) and VHI (p=0.087). Coronary circumference values were not statistically significantly different between the groups of operated children.
Conclusion:
Although there is no consensus regarding the ideal surgical technique for ISS, our results show that CI and sagittal circumference after PCS are better, compared to those after RHT and closer to those of normocephalic children. The values of CSI, CCI and VHI did not differ between the two surgical techniques, demonstrating that both techniques allow an effective and equivalent biparietal remodeling and expansion. As frontal bulging represents an important and prominent deformity in children with ISS, it is important and reasonable that surgical treatment should also be directed towards the correction of this characteristic deformity. In this context, the PCS technique is undoubtedly an effective method.
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