Idiopathic Intracranial Hypertension, often called IIH, is a condition in which the pressure inside the skull is higher than normal. In the past, it was commonly known as pseudotumor cerebri, which means “false brain tumor.” That older name was used because the symptoms can look like those caused by a brain tumor, even though no tumor is present.
What causes IIH?
The word idiopathic means that the exact cause is unknown. In IIH, the brain itself is normal, but the fluid that surrounds the brain and spinal cord-called cerebrospinal fluid (CSF)-is under too much pressure. This increased pressure can affect the brain and the eyes.
IIH is seen most often in women of childbearing age, especially those who are overweight, but it can occur in men and children as well. Certain medications, such as some antibiotics like tetracycline, vitamin A derivatives, and steroids, have been linked to IIH in some people.
Common symptoms
The most common symptom of IIH is headache, which may be daily and can be severe. Other symptoms include:
- Blurred or dim vision
- Temporary vision loss (often lasting seconds)
- Double vision
- Seeing flashing lights
- Ringing or whooshing sounds in the ears (often in time with the heartbeat)
- Nausea or vomiting
Because vision can be affected, IIH is especially important for eye doctors to recognize and monitor.
How IIH affects the eyes
In many patients, IIH causes papilledema, which is swelling of the optic nerve where it enters the back of the eye. This swelling happens because the high pressure around the brain also surrounds the optic nerve. Over time, papilledema can damage the optic nerve and lead to permanent vision loss if not treated.
An eye exam may show optic nerve swelling, blind spot enlargement, or other changes in vision. Visual field testing is often used to track how well the optic nerve is working.
How is IIH diagnosed?
Diagnosing IIH usually involves several steps. Brain imaging, such as an MRI, is done to rule out a tumor or other causes of high pressure. A lumbar puncture (spinal tap) is then used to measure the pressure of the spinal fluid and confirm that it is elevated.
Treatment options
Treatment focuses on lowering the pressure and protecting vision. This may include:
- Weight loss, which can significantly improve symptoms
- Medications like water pills that reduce spinal fluid production
- Regular eye exams to monitor vision
In severe cases, surgery may be needed to protect eyesight.
Why early diagnosis matters
IIH is treatable, but early diagnosis is key. If you have persistent headaches along with vision changes, an eye exam can play an important role in detecting this condition early and preventing long-term vision problems.
If you’ve ever heard the term pseudotumor cerebri, know that it refers to this same condition-now more accurately called idiopathic intracranial hypertension.