Table 3.

Summary of posterior cranial fossa morphology in patients with Chiari malformations stratified according to etiology

	Occipital bone size	PCFV	FM
CM-I (classical type)	Small	Small	Small
CM-I/craniosynostosis	Small	Small	Small
CM-II/(with myelodysplasia)	Small	Small	Large
CM-I/tethered cord syndrome	Normal	Normal	Large
CM-I/cranial settling	Normal	Normal	Normal
CM-I/intracranial space-occupying lesions	Normal	Normal	Normal
CM-I/lumboperitoneal shunt	Normal	Normal	Normal

Abbreviations: PCFV posterior cranial fossa volume, FM foramen magnum, CM-I Chiari malformation type I, CM-II Chiari malformation type II