MRI of Normal Pressure Hydrocephalus

Publication date: Available online 20 January 2016 Source:Seminars in Ultrasound, CT and MRI Author(s): William G. Bradley Normal Pressure Hydrocephalus (NPH) is a syndrome found in the elderly which is characterized by ventriculomegaly and deep white matter ischemia (DWMI) on MRI and the clinical triad of gait disturbance, dementia and urinary incontinence. NPH has been estimated to account for up to 10% of cases of dementia and is significant because it is treatable by ventriculoperitoneal shunting (VPS). Patients with a known cause of chronic communicating hydrocephalus, ie, meningitis or hemorrhage, tend to respond better than patients with the so-called “idiopathic” form, most likely due to poor selection criteria in the past. Good response to shunting has been associated with hyperdynamic CSF flow through the aqueduct. In the early days of MRI, patients with a large CSF flow void extending from the foramen of Monro through the aqueduct to the fourth ventricle had an excellent chance of responding to VPS (p<.003). Today we use phase contrast MRI to measure the volume of CSF flowing through the aqueduct in either direction over a cardiac cycle. When this aqueductal CSF stroke volume (ACSV) is sufficiently elevated, there is an excellent chance of shunt responsiveness (100% PPV in one study). Idiopathic NPH appears to be a “two hit” disease: benign external hydrocephalus (BEH) in infancy followed by DWMI in late adulthood. Since BEH occurs when the sut...
Source: Seminars in Ultrasound, CT and MRI - Category: Radiology Source Type: research