Magnetic resonance venography of achondroplasia: correlation of venous narrowing at the jugular foramen with hydrocephalus.

In achondroplasia, venous narrowing associated with a small skull base leads to elevated venous pressure which impairs cerebrospinal fluid (CSF) absorption, resulting in communicating hydrocephalus. We correlated venous narrowing at the jugular foramina and collateral circulation on magnetic resonance venography (MRV) with ventricular size in 17 patients. Patients were divided into three groups: Group I: progressive hydrocephalus; Group II: nonprogressive hydrocephalus; and Group III: normal ventricular size. The grades of venous narrowing and types of collaterals were well correlated with hydrocephalus groups.