Odontoid Process Hypoplasia and Bipartite Atlas Associated With Atlanto-Axial Instability

Abstract

Surgical treatment of craniocervical junction pathology has evolved considerably in recent years with the implementation of short fixation techniques rather than long occipito-cervical fixation (sub-axial). It is often difficult and sometimes misleading to determine the particular bone and vascular features (high riding vertebral artery, for instance) using only the conventional images in three orthogonal planes (axial, sagittal and coronal). The authors describe a rare clinical case of congenital malformation of the craniovertebral junction consisting of hypoplasia/agenesis of the odontoid process and bipartite atlas associated with atlantoaxial instability which was diagnosed late in life in a patient with a previous history of rheumatologic disease. The authors refer to the diagnostic process, including new imaging techniques, and three-dimensional multiplanar reconstruction. The authors also discuss the surgical technique and possible alternatives.Keywords: Congenital abnormalities; Cervical atlas; Cervical vertebrae; Odontoid process. RESUMO O tratamento cirúrgico da patologia da charneira crânio-cervical tem evoluído consideravelmente nos últimos anos com a implementação de técnicas de fixação curta em detrimento de longas fixações occipito-cervicais (sub-axiais). Frequentemente é difícil e por vezes enganador determinar as variações ósseas e vasculares (artéria vertebral high-riding p.e.) apenas pelas imagens convencionais em três planos ortogonais (axial, sagital e coronal). Os autores descrevem um caso clínico raro de malformação congénita da charneira crânio-cervical constituída por hipoplasia/agenésia da odontoide e atlas bipartido, associado a instabilidade atlanto-axial e diagnosticado tardiamente em doente com antecedentes reumáticos prévios. Descreve-se o processo diagnóstico, incluindo novas técnicas de imagiologia e de reconstrução multiplanar tridimensional. Discute-se a técnica cirúrgica utilizada e possíveis alternativas.Descritores: Anormalidades congênitas; Atlas cervical; vertebras cervicais; Processo odontoide. (axial, sagital y coronal). Los autores describen un caso clínico poco frecuente de malformación congénita de la unión craneocervical que consiste en la hipoplasia/agenesia de la apófisis odontoides y atlas bipartito, asociado con la inestabilidad atlantoaxial, diagnosticado tardiamente en pacientes con enfermedades reumatológicas previas. Los autores relatan el proceso de diagnóstico, incluyendo nuevas técnicas de imagen y la reconstrucción multiplanar tridimensional. Los autores también discuten la técnica quirúrgica y las posibles alternativas. RESUMEN El tratamiento quirúrgico de la patología de la región craneocervical ha evolucionado considerablemente en los últimos años con la aplicación de técnicas de fijación cortas en lugar de fijación occipito-cervical larga (sub-axial). A menudo es difícil y hasta engañoso determinar las características óseos y vasculares (arteria vertebral high-riding, por ejemplo) usando sólo imágenes convencionales en tres planos ortogonales

Skeletal Anomalies in The Neandertal Family of El Sidrón (Spain) Support A Role of Inbreeding in Neandertal Extinction

“…Additionally, this specimen has the shortest odontoid height and a short ventral height for its superior transverse diameter within the available Neandertal sample 55 (Supplementary Information SI4, Supplementary Figs S3, S4). This metric assessment would be consistent with a partial hypoplasia of the dens 56,57 . In modern humans, hypoplasia or even aplasia of the dens of the axis is mostly an isolated, asymptomatic defect and a possible autosomal dominant trait, but it can be associated with C1-C2 instability and neurological symptoms, and it might occur in diverse genetic disorders 57 .…”