What Is Transverse Sinus Stenosis in IIH?

Seeing “transverse sinus stenosis” on your MRI report can be scary, especially since “stenosis” sounds serious. But in the context of Idiopathic Intracranial Hypertension (IIH), it is a very common finding that simply helps explain why your brain is having trouble draining fluid.

The transverse sinuses are the main veins that drain blood out of your head. Stenosis means that these veins are narrowed, creating a bottleneck ^[1]. This bottleneck makes it harder for cerebrospinal fluid (CSF) to drain, contributing to the high pressure in your head ^[2].

What Are the Transverse Sinuses?

Think of your brain’s venous system as a network of plumbing pipes. The transverse sinuses are like the main drainage pipes—or highways—that carry blood away from the brain and down toward the neck ^[3]. When you have IIH, these flexible pipes often become pinched or narrowed, which is what doctors call “stenosis” ^[1]. This narrowing is one of the most classic signs of IIH seen on an MRI ^[4].

The “Chicken or the Egg” Feedback Loop

When patients learn they have a narrowed vein, they often wonder if the narrow vein caused their IIH, or if the IIH caused the narrow vein. Doctors refer to this as a “feedback loop” ^[5][2].

Here is how it works:

1. High pressure in the cerebrospinal fluid (CSF) physically squeezes the flexible walls of the transverse sinus, causing it to narrow ^[2].
2. Because the vein is narrowed, blood and fluid cannot drain out of the head efficiently ^[6].
3. This backup of fluid causes the pressure in the head to rise even further, which squeezes the vein even more ^[5].

This bottleneck often causes pulsatile tinnitus, which is a whooshing sound in your ears that beats in time with your heartbeat. The sound is actually the blood forcefully squeezing through the narrowed part of the vein ^[7][8]. Many patients discover that gently pressing on the side of their neck can temporarily quiet the whooshing sound, as this briefly alters the blood flow.

Will I Need Surgery or a Procedure?

Not necessarily. While transverse sinus stenosis is a real physical narrowing, it often improves on its own. When the overall fluid pressure in your head is lowered through standard IIH treatments like medication (such as acetazolamide) or weight management, the veins can physically “un-pinch” themselves and open back up ^[4].

However, if your vision is severely threatened or if you are suffering from debilitating headaches and medications are not working, your care team may discuss surgical options. One specific option is a minimally invasive procedure called venous sinus stenting ^[8][5].

Instead of open brain surgery, stenting is an endovascular procedure typically done by threading a tiny catheter through a vein in your leg or wrist. A doctor places a small mesh tube (a stent) inside the narrowed transverse sinus to physically prop it open ^[5]. This breaks the feedback loop, allowing fluid to drain normally and lowering the pressure in your head ^[9][10].

Stenting is not for everyone, nor is it risk-free. Before you can even be considered for a stent, doctors must perform a test (an angiogram with manometry) to measure the exact pressures inside your vein. They need to confirm that there is a significant pressure difference—or gradient—across the narrowed area ^[11][12]. If you are not a candidate for a stent, or if your symptoms require a different approach, your doctor might recommend other standard surgeries, such as placing a shunt to drain fluid or fenestration surgery to relieve pressure around the optic nerve.