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--- normaltryckshydrocefalus [2025/10/21 13:39] – skapad akestorck
+++ normaltryckshydrocefalus [2025/10/31 08:12] (aktuell) – akestorck
@@ Rad 1: / Rad 1: @@
 ====== Normaltryckshydrocefalus ======
+===== Summary =====
+Normal pressure hydrocephalus is a form of communicating hydrocephalus characterized by ventricular dilation with normal CSF pressure, classically presenting with the Hakim triad: gait disturbance, cognitive decline, and urinary incontinence. It results from impaired CSF absorption at the arachnoid granulations without a significant rise in intracranial pressure. Differentiation from atrophy-related (ex vacuo) ventriculomegaly is crucial.
+==== Radiographic Features ====
+CT (Non-contrast, preferred for initial evaluation):
+Ventricular enlargement:
+Evans Index (ratio of maximal frontal horn width to maximal internal skull diameter on same axial slice): >0.3 diagnostic; >0.4 strongly suggestive.
+Temporal horn dilatation: Out of proportion to cortical sulcal enlargement.
+Sylvian fissures: Prominent and widened.
+High-convexity sulci: Narrowed or effaced (“disproportionately enlarged subarachnoid space hydrocephalus,” DESH pattern).
+Cortical atrophy: Minimal compared to degree of ventricular enlargement (helps distinguish from ex vacuo dilation).
+Periventricular lucency: Hypoattenuation due to transependymal CSF flow.
+No obstructing lesion (confirms communicating type).
+MRI (Preferred for detailed evaluation):
+Ventricular morphology:
+Evans Index >0.3 confirms ventriculomegaly.
+Callosal Angle (measured on coronal image at posterior commissure):
+Normal: 100–120°
+NPH: <90° (usually 50–80°).
+DESH pattern:
+Enlarged Sylvian fissures + tight high-convexity sulci + ventriculomegaly.
+Flow void sign: Prominent aqueductal and fourth ventricular flow void on T2 or phase-contrast sequences (reflects hyperdynamic CSF flow).
+Periventricular T2/FLAIR hyperintensity: CSF seepage (not necessarily ischemic).
+Phase-contrast cine MRI:
+Measures CSF stroke volume at the aqueduct.
+Stroke volume >42 µL/cycle suggests shunt-responsive NPH.
+Nuclear Medicine (if performed):
+Delayed radionuclide cisternography may show prolonged ventricular retention and delayed cortical activity (rarely used in modern practice).
+Classification / Diagnostic Criteria (Imaging):
+Evans Index >0.3
+Callosal Angle <90°
+DESH pattern present
+No major cortical atrophy or obstructive lesion