Isolated Unilateral Frontosphenoidal Suture Synostosis in Six Patients: Lessons Learned in Diagnosis and Treatment.

Introduction: Due to the rarity of isolated frontosphenoidal suture synostosis clinical diagnosis can be challenging. This study of 6 patients aims to review the clinical, radiological findings, and operative techniques used to correct the underlying pathology. Methods: Patients with isolated frontosphenoidal suture craniosynostosis were selected from a retrospective review of 88 patients with unicoronal synostosis treated during a 3-year period. Two-dimensional photography of patients' soft tissue morphology from the vertex view allowed assessment of the following morphology: frontal bossing, brow depression, nasal tip deviation, and ear position. Quantitative measure of the extent of bony deformity was measured using various angles measured from two-dimensional axial views of computerized tomography scans. Last, technical variations in correction of isolated frontosphenoidal craniosynostosis were collected from operative notes. Results: On the side of isolated frontosphenoidal craniosynostosis, contralateral bossing and ipsilateral brow depression was present in all 6 patients. Ipsilateral nasal tip deviation was seen in 3 out of the 6 patients. Ear position was symmetrical in the cranial-caudal and anterior-posterior axes. No radiological evidence of harlequin deformity was seen on skull X-ray in all 6 patients, but computerized tomography scans demonstrated isolated frontosphenoidal suture craniosynostosis. The angle drawn between the foramen magnum, sella turcica, and anterior cribriform plate in 3 of 6 patients showed deflection of the anterior cranial fossa opposite to the side of isolated frontosphenoidal suture craniosysnotosis. There was no difference in the angle between the petrosal pyramid and the midline. In all patients, operative technique involved taking a deeper fron-to-orbital bandeau to capture and reshape the pathological suture. Conclusions: In isolated frontosphenoidal suture craniosynostosis, contralateral bossing and ipsilateral flattening of the forehead were the most consistent clinical features with nasal tip deviation away from the side of pathology less consistent. Ear position is unaffected. Measurements of various angles of the skull base were not consistent. A deeper vertical osteotomy at the site of isolated frontosphenoidal suture craniosysnotosis on removing the fronto-orbital bandeau was 1 operative technical variation.