Chiari type 1-a malformation or a syndrome? A critical review.

OBJECTIVE: As the understanding of pathophysiology behind Chiari malformation still is limited, the treatment of Chiari malformation type 1 remains rather empirical. This may result in suboptimal treatment strategy and outcome in many cases. In this review, we critically address whether the condition known today as Chiari malformation type I should rather be denoted Chiari syndrome.

METHODS: The current knowledge of Chiari malformation type 1 is summarized from the historical, etymological, genetic, clinical, and in particular pathophysiological perspectives.

RESULTS: There are several lines of evidence that Chiari malformation type 1 represents a condition significantly different from types 2 to 4. Unlike the other types, the type 1 should rather be considered a syndrome, thus supporting the reasons to reappraise the traditional classification of Chiari malformations.

CONCLUSION: We propose that Chiari malformation type 1 should rather be denoted Chiari syndrome, while the notation malformation is maintained for types 2-4.