Chiari 1 malformation with basilar invagination


Chiari I malformation consists of downward tonsillar herniation and syringomyelia. As an association with this syndrome there is also basilar invagination as shown by flat basioccipt (platybasia) and upward odontoid projection. Normally the dens should project up to 3 mm above Chamberlain line and 5 mm above Mc Gregor line.