'Sneeze syncope', basilar invagination and Arnold-Chiari type I malformation.
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.
D000328:Adult; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D010985:Platybasia / Q000150:complications* / Q000000981:diagnostic imaging; D011859:Radiography; D012886:Skull / Q000000981:diagnostic imaging; D012912:Sneezing; D013575:Syncope / Q000209:etiology*