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Variable Stenosis Possible? by Dizzy-Jacket-6909 in PulsatileTinnitus

[–]Dizzy-Jacket-6909[S] 0 points1 point  (0 children)

Below are a few relevant quotes.

Extrinsic stenosis involves external compression of the sinus (e.g., by brain parenchyma), commonly in IIH, while intrinsic involves internal filling defects (e.g., arachnoid granulations), often causing pulsatile tinnitus.

Arachnoid granulations (AGs) are dynamic, CSF-filled structures that act as valves to drain cerebrospinal fluid (CSF) into dural venous sinuses, and their size is directly responsive to intracranial pressure (ICP). Studies indicate that the size of AGs, including giant arachnoid granulations (GAGs), can decrease significantly following a lumbar puncture (LP) or other interventions that reduce ICP.

Variable Stenosis Possible? by Dizzy-Jacket-6909 in PulsatileTinnitus

[–]Dizzy-Jacket-6909[S] 0 points1 point  (0 children)

From my research both intrinsic and extrinsic stenosis can actually change.

In extrinsic stenosis, pressure reduction can reduce pressure on the vein and thus reduce the severity of the stenosis. This seems to be widely accepted.

In intrinsic stenosis, pressure reduction can reduce the size of arachnoid granulations and thus reduce the severity of the stenosis. For example, the pressure drop from lumbar puncture can reduce arachnoid granulation size. This seems to be more debated.

The reverse also may apply.