What is Idiopathic Intracranial Hypertension (IIH)?
Idiopathic Intracranial Hypertension (IIH) refers to increased pressure inside the skull without a known cause. Breaking it down:
- Idiopathic means “unknown cause.”
- Intracranial refers to “inside the skull.”
- Hypertension means “high pressure.”
In IIH, the cerebrospinal fluid (CSF) surrounding the brain and spinal cord builds up pressure. Historically, this condition was called pseudotumor cerebri, meaning “false brain tumor,” because its symptoms mimic those caused by a brain tumor. While the term pseudotumor is now outdated, some healthcare providers may still use it. It could be also referred to as chronic venous hypertension.
Symptoms of Idiopathic Intracranial Hypertension
IIH symptoms vary, but the most common ones include:
- Persistent headaches, often worse in the morning or when bending down.
- Blurred or temporary vision loss, especially with activities like coughing or lifting.
- Pulsatile tinnitus (a rhythmic “whooshing” sound in one or both ears).
- Dizziness and double vision.
Additional symptoms may include fatigue, difficulty concentrating, and even depression. Unfortunately, IIH is sometimes misdiagnosed as a migraine, leading to delays in appropriate treatment.
How is Idiopathic Intracranial Hypertension Diagnosed?
IIH diagnosis begins with an eye exam by an ophthalmologist or neurologist, who will look for papilledema—swelling of the optic nerve caused by increased intracranial pressure. A visual field test may also detect subtle vision changes.
To confirm the diagnosis and identify potential causes, doctors use imaging tests like:
- MRI or CT scans to check for brain abnormalities or signs of increased pressure.
- Specialized MRI techniques, such as magnetic resonance venography (MRV), to detect venous sinus stenosis (narrowing of veins that drain blood from the brain).
Finally, a spinal tap (lumbar puncture) measures the opening pressure of the cerebrospinal fluid and helps confirm the diagnosis.
Risk Factors for Idiopathic Intracranial Hypertension
Certain factors can increase the risk of developing IIH, including:
- Being a woman aged 20–50.
- Carrying excess weight or experiencing recent significant weight gain.
- Using certain medications, such as steroids, high doses of vitamin A, or tetracyclines.
- Rarely, infections or blood clots in brain veins can contribute.
