Headache, confusion and dysphagia post VP shunt for NPH
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Bilateral convexity subdural collections of fluid without obvious internal membranes or acute blood suggesting hygroma rather than chronic haematoma. Note subtle effacement of both frontal lobe sulci suggesting mass effect. These findings contrast with the preoperative scans.
One of the major issues associated with shunting the ventricles of elderly patients is the development of subdural collections due to a excessive reduction in ventricular volume ("overshunting") leading to a subdural "dead space" that can fill with acute blood (haematoma) from the stretching of vessels traversing the space, or bland fluid = hygroma. Differentiating hygroma from chronic haematoma is always difficult on CT. The presence of membranes (granulation tissue) in the fluid indicates old haematoma but they can be very hard to see.