ABSTRACT
INTRODUCTION Chiari malformations are a group of conditions with different etiologies. They are all similar; however, in that they involve abnormalities in the posterior fossa and craniovertebral junction. These abnormalities often are associated with the presence of hydrocephalus due to changes they cause in cerebrospinal fluid (CSF) flow at the level of the craniovertebral junction. Any posterior fossa/craniovertebral junction abnormality has the potential to affect CSF flow by fourth ventricular outlet atresia or obstruction, venous flow abnormalities or, rarely, other mechanisms. This chapter reviews the most common Chiari malformations associated with hydrocephalus and other similar conditions and discusses development and pathology, presentation, imaging, and management options.
