Basilar invagination associated with chiari malformation type I: A literature review

Basilar invagination (BI) and Chiari malformation type I (CM-I) are very important anomalies that introduce instability and compression in the occipitocervical transition region and have complex clinical characteristics. These anomalies vary according to the affected structures. The present study revises current knowledge regarding the anatomy, anatomo-physiology, clinical manifestations, and radiological findings of these entities and the associated surgical treatment approaches. A bibliographic survey was performed through a search in the Medline, PubMed, SciELO, Science and LILACS databases. When associated, these craniovertebral malformations result in neurological deficits due to neural parenchyma compression; however, the presence of microtraumas due to repetitive lesions caused by the bulb and cervical marrow instability has been highlighted as a determinant dysfunction. Surgical treatment is controversial and has many technical variations. Surgery is also challenging due to the complex anatomical characteristics and biomechanics of this region. Nevertheless, advances have been achieved in our understanding of related mechanisms, and compression and atlantoaxial instability are considered key elements when selecting the surgical approach.

Estudo clínico-radiográfico da subluxação atlantoaxial congênita em cães / Clinic-radiographic study of congenital atlantoaxial subluxation in dogs

Neste estudo foram analisadas ficha clínica e radiografias simples de cães com diagnóstico de subluxação atlantoaxial congênita, obtidos junto ao Serviço de Radiologia do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, no período de janeiro de 1990 a dezembro de 1999. Durante este período, foram identificados sete cães com alterações do processo odontóide do áxis (agenesia ou hipoplasia), levando à instabilidade da articulação atlantoaxial e conseqüente compressão medular. Todos os animais, com idade igual ou inferior a um ano, apresentavam sinais neurológicos. O diagnóstico definitivo foi firmado mediante as alterações observadas em exame radiográfico simples.