Three-dimensional study of 31 cases of synostotic anterior plagiocephaly before and after surgical management the Lille protocol

Crouzon syndrome: posterior fossa volume studies in vestibular orientation

INTRODUCTION

With the increasing possibilities of surgical treatment addressing the complex spectrum of defects in Crouzon syndrome (CS), it is of utmost importance to obtain accurate assessment of the malformation. Evaluating the volume of the posterior fossa is of great importance since many authors, considering that its volume is always decreased, favor posterior fossa enlargement as a first step in the treatment of CS.

MATERIAL AND METHODS

We studied CT scans of children with CS, which were vestibular-oriented (VO) in order to conform with physiological landmarks, and we measured intracranial volume by manual segmentation; these abnormal CT scans were superposed with VO 3D-CT scanners of age-matched controls. We studied the volume index of the posterior fossa for each CS patient defined as the ratio of its volume in CS patients with the normal for age calculated from normal controls.

RESULTS

We studied the imaging of 41 children with CS and 70 control. Among CS patients, the volume of the posterior fossa was increased in 10, compared with control. We found closure of the sphenoidal synchondrosis was correlated with age and with the width of the posterior fossa, but not with its length nor with the posterior fossa volume index.

CONCLUSION

Segmentation on VO-CT scanner and superposition with CT scanners of normal controls is a powerful tool for the study of the impact of CS or other synostoses on volume and shape. We found that CS is more heterogeneous than previously thought, and surgical strategies should be adapted accordingly.

Extraocular muscle positions in anterior plagiocephaly: V-pattern strabismus explained using geometric mophometrics

INTRODUCTION

Ophthalmological involvement in anterior plagiocephaly (AP) due to unicoronal synostosis (UCS) raises management challenges. Two abnormalities of the extraocular muscles (EOM) are commonly reported in UCS without objective quantification: (1) excyclorotation of the eye and (2) malposition of the trochlea of the superior oblique muscle. Here we aimed to assess the positions of the EOM in AP, using geometric morphometrics based on MRI data.

MATERIALS AND METHODS

Patient files were listed using Dr WareHouse, a dedicated big data search engine. We included all patients with AP managed between 2013 and 2018, with an available digital preoperative MRI. MRIs from age-matched controls without craniofacial conditions were also included. We defined 13 orbital and skull base landmarks in order to model the 3D position of the EOM. Cephalometric analyses and geometric morphometrics with Procrustes superimposition and principal component analysis were used with the aim of defining specific EOM anomalies in UCS.

RESULTS

We included 15 preoperative and 7 postoperative MRIs from patients with UCS and 24 MRIs from age-matched controls. Cephalometric analyses, Procrustes superimposition and distance computations showed a significant shape difference for the position of the trochlea of the superior oblique muscle and an excyclorotation of the EOM.

CONCLUSIONS

Our results confirm that UCS-associated anomalies of the superior oblique muscle function are associated with malposition of its trochlea in the roof of the orbit. This clinical anomaly supports the importance of MRI imaging in the surgical management of strabismus in patients with UCS.