'Sneeze syncope,' basilar invagination and Arnold Chiari type I malformation

Abstract

Syncope precipitated by sneezing in an adult male associated with an Arnold Chiari type I malformation and basilar invagination presents a clinical problem in the differential diagnosis and pathological anatomy of Valsalva related syncope. An abnormally acute clivoaxial angle, small foramen magnum, and type I Arnold Chiari malformation appear to be a combination of features intolerant of Valsalva induced changes in cerebral volume, brain stem position, CSF fluid dynamics, or blood vessel relationships. Proposed mechanisms of pressure transmission to the area of intracranial pathology are discussed.