The normal evolution of the cranium in three dimensions.

Insight into the growth and development of the normal newborn cranial shape is essential to monitor cranial development, to detect and diagnose abnormal skull shapes, and for the long-term follow-up of craniosynostosis surgery. The aim of this study was to analyse the growth pattern of the cranial shape of infants during the first years of life using 3D stereophotogrammetry and 3D computed tomography (CT) with advanced 3D evaluation techniques. A large set of 3D photographs (n=199) and CT scans (n=183), taken between ages 0 and 54 months, was collected. Cranial shapes with artefacts and asymmetries were removed. Total volumes and intracranial volumes were obtained, as well as 3D and 2D measurements, including the cranial width, cranial length, cranial index, and suture lengths. Growth maps were created for all modalities to indicate 3D growth over time. For the final analysis, a total of 130 3D photographs, 94 hard tissue CT scans, and 76 soft tissue CT scans were used. 3D and 2D measures, volumes, growth maps, and growth animations were obtained. A non-uniform growth was revealed by the 3D growth maps. This study addresses the need for normative cranial evolution data to monitor healthy cranial development and for detection, follow-up, and treatment planning in craniosynostosis.

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 new method for three-dimensional evaluation of the cranial shape and the automatic identification of craniosynostosis using 3D stereophotogrammetry.

Craniosynostosis is a congenital defect which can result in abnormal cranial morphology. Three dimensional (3D) stereophotogrammetry is potentially an ideal technique for the evaluation of cranial morphology and diagnosis of craniosynostosis because it is fast and harmless. This study presents a new method for objective characterization of the morphological abnormalities of scaphocephaly and trigonocephaly patients using 3D photographs of patients and healthy controls. Sixty 3D photographs of healthy controls in the age range of 3-6 months were superimposed and scaled. Principal component analysis (PCA) was applied to find the mean cranial shape and the cranial shape variation in this normal population. 3D photographs of 20 scaphocephaly and 20 trigonocephaly patients were analysed by this PCA model to test whether cranial deformities of scaphocephaly and trigonocephaly patients could be objectively identified. PCA was used to find the mean cranial shape and the cranial shape variation in the normal population. The PCA model was able to significantly distinguish scaphocephaly and trigonocephaly patients from the normal population. 3D stereophotogrammetry in combination with the presented method can be used to objectively identify and classify the cranial shape of healthy newborns, scaphocephaly and trigonocephaly patients.

The computed cranial focal point.

INTRODUCTION: Stereophotogrammetry is a radiation-free method for monitoring skull development after craniosynostosis repair. Lack of clear fixed reference points complicate longitudinal comparison of 3D photographs. Therefore we developed the 'computed cranial focal point' (CCFP). METHODS: The CCFP was calculated in segmented 3D CT-scans of 36 adult subjects using Matlab. The robustness of the CCFP calculation was evaluated in predefined hemi-ellipsoid shapes. Finally we used the CCFP in two clinical cases to correlate CT data with 3D-photographic data. RESULTS: The CCFP calculation was found to be hardly influenced by incomplete or deformed surface data which resulted in small deviations (<2.5 mm). The average position of the CCFP of the skin relative to the sella turcica was at (0.0, 27.1, 19.4) mm, with CCFPσ (0.6, 4.6, 3.9) mm. The mean difference between the CCFP for the skull and skin was (-0.1, 1.9, -1.4) mm, with CCFPσ (0.5, 1.4, 1.0) mm. Using the CCFP in two cases to correlate the skin from a 3D-photo and the segmented skin from a CT-scan resulted in absolute mean differences of 0.7 and 2.3 mm, with a standard deviation of 1.1 mm in both cases. CONCLUSION: The CCFP calculation is a robust method to define a reference point relative to the sella turcica based on the skin or cranial bone surfaces. The CCFP can be used to correlate 3D photographs with CT-scan data or for longitudinal radiation-free comparison of 3D-photos.

A new test set-up for skull fracture characterisation.

Skull fracture is a frequently observed type of severe head injury. Historically, a variety of impact test set-ups and techniques have been used for investigating skull fracture. The most frequently used are the free-fall technique, the guided fall or drop tower set-up and the piston-driven impactor set-up. This document proposes a new type of set-up for cadaver head impact testing which combines the strengths of the most frequently used techniques and devices. The set-up consists of two pendulums, which allow for a 1 degree of freedom rotational motion. The first pendulum is the impactor and is used to strike the blow. The head is attached to the second pendulum using a polyester resin. Local skull deformation and impact force are measured with a sample frequency of 65 kHz. From these data, absorbed energy until skull fracture is calculated. A set-up evaluation consisting of 14 frontal skull and head impact tests shows an accurate measurement of both force and local skull deformation until fracture of the skull. Simplified mechanical models are used to analyse the different impacting techniques from literature as well as the new proposed set-up. It is concluded that the proposed test set-up is able to accurately calculate the energy absorbed by the skull until fracture with an uncertainty interval of 10%. Second, it is concluded that skull fracture caused by blunt impact occurs before any significant motion of the head. The two-pendulum set-up is the first head impact device to allow a well-controlled measurement environment without altering the skull stress distribution.