Definition of the Adult Chiari Malformation: A Brief Historical Overview

Ghassan K. Bejjani, MD, Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania

Neurosurg Focus. 2001;11(1) 

In This Article

Abstract and Introduction

With the widespread use of newer neuroimaging techniques and modalities, significant tonsillar herniation is being diagnosed in more than 0.5% of patients, some of whom are asymptomatic. This puts the definition of the adult Chiari malformation to the test. The author provides a historical review of the evolution of the definition of the adult Chiari malformation in the neurosurgery, radiology, and pathology literature.

There is confusion in the literature regarding the concept of Chiari I malformation or adult Chiari malformation. Recent advances in neuroimaging modalities and their widespread use has led to an increase in the number of patients with radiological evidence of tonsillar herniation, some of whom are asymptomatic, raising questions as to its true clinical relevance. This is especially true because its incidence has been found to be between 0.56%[37] and 0.77%[65] on MR imaging studies, as well as 0.62% in brain dissection studies.[41] With that in mind, we attempted to review the various historical steps that marked the evolution of the definition of adult Chiari malformation.