gms | German Medical Science

Objective: The term "Chiari 0 malformation" was first used by Bermans J. Iskandar in a presentation given at a meeting of the Pediatric Neurosurgery Section of the American Association of Neurological Surgeons (AANS) in Louisiana, New Orleans, in December 1997. Iskandar and his working group defined Chiari 0 malformation as an obstruction of the outlets of the fourth ventricle caused by a small and malformed posterior fossa without evidence of cerebellar tonsillar herniation. Since the term was coined only a few years ago and is used variably in the medical literature, we use it more broadly to refer to all types of functional obstruction of the craniocervical junction without tonsillar descent.

Methods: In a total of 149 patients with impaired CSF flow pulsations at the craniocervical junction, we separately studied those patients with neither Chiari type I nor type II nor type III malformations.

Results: Our study group consisted of 16 patients. There were 9 women and 7 men with a mean age of 41 years (median age: 41 years; range: 2-72 years). Eight patients presented with syringomelia and 6 patients had hydrocephalus. An obstruction of the foramen of Magendie was diagnosed in 5 patients. Static stenosis of the foramen magnum was the underlying problem in 6 patients and dynamic narrowing in 2 patients. Cysts were detected in 3 cases. All patients underwent surgical treatment. As in surgery for the other types of Chiari malformations, the objective of surgical treatment was to restore normal CSF flow pulsations.

Conclusions: Our study suggests that the wider use of the term "Chiari 0 malformation" as defined here appears reasonable and practicable and should therefore be recommended.