The role of MRI-CSF flowmetry in the diagnosis of idiopathic normal pressure hydrocephalus

Abstract

: Background: Normal pressure hydrocephalus is a gloomy entity with no definite cause known till date. The classical clinical triad includes gait apraxia, urinary incontinence and different grades of cognitive dysfunction as dementia. NPH is considered the first treatable type of dementia as it differs from other dementias in that the symptoms can show clinical recovery & regression with CSF diversion . Many tests have been employed in the diagnosis of idiopathic NPH, including invasive methods serious is non-invasive techniques are required to increase the sensitivity and specificity of routinely used imaging . 6 patients (24%) were diagnosed as atrophic dilatation with hypo dynamic CSF flow across the aqueduct in the PC MRI study. In our study, we found that normal CSF flow throughout the cardiac cycle show free aqueductal pulsatile CSF flow as a cranial flow during CSF diastole (hyper intense signal) and caudal flow during systole (hypo intense signal). In our study, we found that at a cut off value for aqueductal SV of about 42 ul/cycle. Aqueductal stroke volume (> 42) shows sensitivity of about (93.3%) & specificity of about (75%) with total accuracy of about (89.5%) in predicting shunt responsiveness in NPH patients. Conclusion: Phase contrast MRI CSF Flowmetry was found to be of high sensitivity and specificity in diagnosing NPH & differentiating it from atrophic dilatation. It is simple, fast and non-invasive effective method that adds more to the total accuracy of the conventional MRI examination as it provide valuable additional information & reducing rates of complications and predicting shunt responsiveness.