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CSF overshunting - intracranial hypotension

Case contributed by Dr Andrew Dixon

Presentation:

Headaches with a ventricular peritoneal shunt in situ. ? Blocked shunt. Past history of posterior fossa cerebrellar astrocytoma removal.

Patient Data:

Age: 20
Gender: Female

CT Brain

Modality: CT

VP shunt in situ. Slit-like 3rd and lateral ventricles. Distended dural venous sinuses which are of normal density. Appearances suggest intracranial hypotension secondary to CSF overshunting. 

Modality: MRI

VP shunt in-situ. Slit-like lateral and 3rd ventricles. Distended dural venous sinuses with "venous distension sign" present on the sagittal T1 images.  Thin pachymeningeal enhancement. Appearances are consistent with intracranial hypotension secondary to CSF overshunting.  

8 months earlier

Modality: CT

CT Brain from 8 months earlier reveals that the ventricles were previously less slit-like and that the dural venous sinuses were not as obviously distended. 

8 months earlier

Modality: MRI

MR Brain from 8 months earlier reveals that the ventricles were previously less slit-like and that the dural venous sinuses were not as distended with normal concave lower margin of the transverse sinus on the sagittal images (no "venous distension sign"). 

Venous distension sign

Modality: MRI

Sagittal T1 images at the level of the mid transverse sinus in the same patient. The upper image with red arrow demonstrates the "venous distension sign" of intracranial hypotension with a bulging convex inferior margin of the transverse sinus. The lower image from a scan 8 months earlier shows the original normal appearances of the transverse sinus with a concave inferior margin.

Case Discussion:

Reduced ventricular size with positive venous distension in keeping with intracranial hypotension, presumably secondary to CSF overshunting. This has occurred since the scans from 8 months earlier. This case is a good example of the "venous distension sign".

With thanks to Dr Anthony Kam.

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