Key takeaways:
Idiopathic intracranial hypertension (IIH) (formerly known as a pseudotumor) is a condition that results from excess cerebrospinal fluid that surrounds the brain. It can lead to headaches that range from mild to debilitating.
It’s more common in younger people, women, and people with obesity. But experts still don’t understand what causes it or why being in these groups increases your risk of getting IIH.
There are several treatment options for IIH. These include medications, procedures to remove excess fluid, or surgery to help prevent fluid buildup.
Idiopathic intracranial hypertension (IIH) is a condition that occurs when there is a buildup of the fluid that naturally surrounds the brain, called cerebrospinal fluid (CSF). Idiopathic means that experts still don’t know why this happens in some people. And intracranial hypertension means there is abnormally high pressure inside the skull, which is the result of the excess fluid.
In the past, this condition was called pseudotumor cerebri. This is an outdated term that was originally used because the symptoms of it are similar to those of a brain tumor, like headaches and vision changes. But this name was understandably misleading. We’ll explain more about the causes of IIH, symptoms, and treatments for this condition.
What causes idiopathic intracranial hypertension?
IIH occurs when there is too much cerebrospinal fluid (CSF). Under normal circumstances, this fluid normally serves as a cushion for the brain and helps provide the brain with nutrients. The body is continuously making and reabsorbing CSF to keep the amount of fluid steady. But if there is too much CSF squeezed into the skull, the pressure inside the skull begins to rise.
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Other medical conditions, like brain tumors, can also raise the pressure in the skull. But actually, there’s nothing wrong with the brains of people with IIH: The pressure is coming from the CSF.
Experts still don't know exactly what causes IIH. They think it may either be that the body makes too much CSF or that it can’t reabsorb it fast enough. But in the meantime, they have observed some characteristics that put people at a higher risk of having this condition:
Gender: Over 90% of people with IIH are genetically female.
Age: IIH is usually diagnosed between the ages of 20 and 40. The average age that people get diagnosed with IIH is 30 years old.
Weight: People with increased body fat are more likely to have this condition. Over 90% of people with IIH are classified as having obesity.
What are the symptoms of idiopathic intracranial hypertension?
The main symptom associated with IIH is a headache. People with IIH usually describe a diffuse, press-like headache that can range from mild to severe. The headache also typically worsens when lying flat (which allows more CSF to accumulate in the skull). And sometimes the pain can spread down into the neck and shoulders.
In addition to headaches, people with IIH also experience:
Nausea and vomiting, which is a common symptom that accompanies anything that increases pressure in the skull.
Blurry vision or eye pain, which can result from the pressure in the brain pressing on the optic nerve that connects the brain to the eyes.
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What is the treatment for intracranial hypertension?
Fortunately, someone with IIH has several options for treatment. And they all work by lowering the amount of fluid surrounding the brain in different ways. These include:
Medications: Those that lower the amount of CSF production include acetazolamide (Diamox) or furosemide (Lasix).
Weight loss: Losing weight can help with symptoms in some cases. Evidence shows that losing 6% to 10% of body weight might decrease the symptoms of IIH.
A lumbar puncture: This is a procedure in which a trained provider inserts a small needle in the lower back to drain CSF from the brain. (The CSF actually flows around the brain as well as the entire spine. This allows the provider a safe, convenient way to remove some of the CSF from its reservoir.) This treatment is often only a temporary solution, however, as the CSF tends to gradually build up again over time.
A ventriculoperitoneal shunt: This is a tube that runs from inside the skull down into the abdomen. This tube lets the CSF continually drain into the abdomen, where it is eventually reabsorbed. A specialist can implant this device through a surgical procedure. And because the tube travels under the skin, nobody sees it after it’s in place.
How serious is idiopathic intracranial hypertension?
Idiopathic intracranial hypertension ranges from being mild and temporary to serious and more longer term. In mild cases, the symptoms may improve with a small amount of medication or go away on their own.
In other cases, IIH leads to headaches that can feel severe — and significantly disrupt your day-to-day activities. The good news is that symptoms usually improve when people get treatment.
While IIH does not typically lead to any long-term complications, in some cases it can lead to vision loss. But this only occurs in less than 10% of people with IIH. Still, if you are having any symptoms involving your vision, it is best to see your provider. They can check your eyes and make sure you are on the right treatment to avoid any permanent changes to your vision.
The bottom line
Idiopathic intracranial hypertension (IIH) can sound like a scary condition, especially when people refer to it as a pseudotumor. But it is actually caused by extra CSF fluid surrounding the brain rather than a problem with the brain itself. Still, it can cause pretty severe, debilitating headaches. Luckily, there are a number of different treatment options to remove this fluid and alleviate your symptoms, and many people will grow out of this condition as they grow older.
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References
American Academy of Ophthalmology. (2020). What is idiopathic intracranial hypertension?
Best, J., et al. (2013). The incidence of blindness due to idiopathic intracranial hypertension in the UK. The Open Ophthalmology Journal.
Chen, J., et al. (2014). Epidemiology and risk factors for idiopathic intracranial hypertension. International Ophthalmology Clinics.
Hoffmann, J., et al. (2018). European headache federation guideline on idiopathic intracranial hypertension. The Journal of Headache and Pain.
National Health Service. (2019). Intracranial hypertension.
National Institutes of Health. (2021). Idiopathic intracranial hypertension.
Subramaniam, S., et al. (2017). Obesity and weight loss in idiopathic intracranial Hypertension: A narrative review. Journal of Neuro-Ophthalmology.
Wall, M., et al. (2015). Risk factors for poor visual outcome in patients with idiopathic intracranial hypertension. Neurology.
Yri, H. M., et al. (2012). Idiopathic intracranial hypertension is not benign: A long-term outcome study. Journal of Neurology.
