Hydrocephalus MRI

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Syed Ahsan Hussain, M.D.[2]

MRI[edit | edit source]

• The MRI findings are given below:^[1][2][3]
• Ventricular enlargement not entirely attributable to cerebral atrophy or congenital enlargement (Evans index >0.3).
• No macroscopic obstruction to CSF flow.
• Enlargement of the temporal horns of the lateral ventricles not entirely attributable to hippocampus atrophy.
• Callosal angle of 40º or greater. Evidence of altered brain water content, including periventricular signal changes on CT and MRI not attributable to microvascular ischemic *Changes or demyelination. An aqueductal or fourth ventricular flow void.
• 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 is sufficiently elevated, there is an excellent chance of shunt responsiveness (100% positive predictive value).
• Idiopathic NPH appears to be a "two-hit" disease-benign external hydrocephalus (BEH) in infancy followed by DWMI in late adulthood.
• As BEH occurs when the sutures are still open, these infants present with large heads, a finding also noted in patients with NPH.
• Although BEH has been attributed to immature arachnoidal granulations with decreased CSF resorptive capacity, this now appears to be permanent and may lead to a parallel pathway for CSF resorption via the extracellular space of the brain.
• With DWMI, the myelin lipid is lost, exposing the polar water molecules to myelin protein, increasing resistance to CSF outflow and leading to backing up of CSF and hydrocephalus.

Marked Hyrocephalus

Aqueductal Stenosis[edit | edit source]

Images courtesy of RadsWiki

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  Fetal MRI: Aqueductal stenosis
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  Fetal MRI: Aqueductal stenosis
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  Fetal MRI: Aqueductal stenosis
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  Fetal MRI: Aqueductal stenosis
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  Fetal MRI: Aqueductal stenosis

Diffusion MRI[edit | edit source]

It gives better visualisation of microstructral changes in periventricular white matter areas than conventional MRI^[4]

References[edit | edit source]

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