The Arnold-Chiari malformations.

Abstract

THE ARNOLD-CHIARI malformation is more accurately designated the Chiari-Arnold malformation since Hans Chiari's first publication on this subject preceded Julius Arnold's by three years.1-3In his initial report, translated below, Chiari divided the hindbrain anomalies occurring in some hydrocephalic children into three types. Subsequently, two of Arnold's students gave the name Arnold-Chiari malformation to Chiari's second type, which they, like Chiari, found in association with meningomyelocele.4The eponymic error has been perpetuated ever since, though the term is now loosely applied to encompass a whole spectrum of related developmental defects. There is considerable individual variation in the pathological composition of the Arnold-Chiari malformation, but in general, Chiari's type II changes are common in infants with hydrocephalus and meningomyelocele, and the type I changes are encountered occasionally in older children and adults. The detection of the latter cases has been aided greatly by the recent development of satisfactory techniques