What is idiopathic intracranial hypertension (IIH)?
Idiopathic intracranial hypertension (IIH) is a build-up of cerebrospinal fluid around the brain, which causes increased pressure inside the skull (intracranial hypertension); however, people with IIH are still alert and orientated and able to function. Idiopathic means that the cause has not been identified.
IIH was previously known as pseudotumor cerebri which translates to “false brain tumor” because its symptoms resemble those caused by brain tumors.
IIH more commonly occurs in women aged between 20 and 50 and is estimated to affect more than 100,000 people in the United States. Only 5-10% of those affected are men.
What causes idiopathic intracranial hypertension (IIH)?
Although several conditions and medications are known to cause intracranial hypertension, the term “idiopathic” means no cause has been identified.
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spinal cord. It flows in and around the hollow spaces of the brain and spinal cord, protecting and cushioning them. Because our skull is rigid and cannot expand, any condition that causes an increase in the production of CSF or a decrease in its reabsorption can cause pressure build-up.
Risk factors that increase the likelihood of developing IIH include:
- Age, particularly aged 20 to 50 years
- Anemia (a lack of red blood cells) or polycythemia (too many red blood cells)
- Antibiotics, such as doxycycline, minocycline, and nitrofurantoin
- Barrter's syndrome (a kidney disorder) and the use of NSAIDs such as indomethacin or ketoprofen
- Chemotherapy medications
- Chronic kidney disease
- Female sex
- Obesity (BMI greater than 30)
- Oral contraceptives
- Thyroid replacement in children with hypothyroidism
- Vitamin A derivatives, such as isotretinoin
- Withdrawal of corticosteroids
What are the symptoms of idiopathic intracranial hypertension (IIH)?
The symptoms of idiopathic intracranial hypertension (IIH) resemble those of a brain tumor and reflect increased levels of pressure inside the skull.
Symptoms may include:
- Vision changes, such as blurred vision or double vision
- Vision loss, especially in peripheral vision
- Nausea and vomiting
- Neck stiffness
- Tinnitus (ringing in the ears)
- Walking difficulties
How is idiopathic intracranial hypertension (IIH) diagnosed?
If you have any symptoms suggestive of idiopathic intracranial hypertension (IIH), such as vision changes or persistent headaches, see your doctor.
Your doctor will perform a physical examination and listen to your medical and medication history. They may perform several tests, to help either diagnose IIH or rule out other conditions. These may include brain imaging, such as MRI or CT scans, a lumbar puncture, or eye and vision examinations.
IIH is diagnosed if you have increased pressure on your brain and no other cause can be found.
How is idiopathic intracranial hypertension (IIH) treated?
Although idiopathic intracranial hypertension (IIH) isn’t a brain tumor, it can still cause serious problems if left untreated.
Medications that potentially could be contributing to the idiopathic intracranial hypertension (IIH) should be discontinued. This usually leads to resolution of IIH within two to four weeks.
Weight loss, through dietary modification, salt restriction, and exercise has also been associated with an improvement of IIH in obese people.
Other treatments may include:
- Fluid and salt restriction
- Medications, such as diuretics to remove extra fluid from the body or a short course of steroids
- Spinal taps to remove pressure
- Surgery, such as placement of a ventriculoperitoneal (VP) shunt or eye surgery on the optic nerve to ease the pressure