IIH (old term: pseudotumor cerebri) is a condition mostly affecting young obese women resulting in high brain or intracranial pressure, usually from no obvious reason. Normal intracranial pressure in adults is up to 10-20cm or 200mm of H₂O, and probably up to 25-28cm in children, depending upon their age.

What are symptoms of IIH?

Following are common symptoms:

1. Headache: Severity of headache ranges from debilitating 24/7 pain to minimal pressure type feeling. Patient may also complain of sensitivity to light and noise, nausea, and dizziness. Headache may be worse upon waking up, with coughing or sneezing, or with activities that may raise pressure in the head, such as straining while passing bowels, or having an orgasm.
2. Vision problems: Blurred vision is a common symptom, and if the pressure is high enough, patient may also have episodes of double vision, or complete loss of vision.
3. Ear symptoms: There may be a feeling of ear popping, or heart beat type of feeling in the ear, the so-called pulsatile tinnitus.
4. Rarely, there may be facial numbness or weakness.
5. Finally, many patients have no symptoms at all, and the condition is discovered on a routine eye examination.

 

What are typical signs or the finding on examination of IIH?

Most patients are obese, usually with history of recent significant weight gain. BMI is usually significantly elevated. The more specific finding on examination is the swelling inside the eyes, the disc edema. Rarely, an eye muscle may not work well, and that eye may not move all the way away from the nose. There may be evidence of visual loss on bedside examination. Rarely, there may be facial weakness. Other than that, there is no particular finding on examination.

 

How is the diagnosis of IIH confirmed?

Confirmation of IIH requires confirmation of high intracranial pressure. Theoretically, one can measure intracranial pressure in three different ways: a. directly within the skull (almost never done), b. accessing the CSF cavity in the neck (doable but risky, and not the procedure of choice), and the c. accessing the CSF cavity in the lower back. Lower back is a relatively safe area, as there is no risk of direct injury to either brain or the spinal cord.

 

What tests are required to investigate IIH?

1. MRI of brain: If patient’s history and examination is suggestive of high intracranial pressure, the first next step is to have a brain scan done. MRI of brain is preferred, unless for some reason patient cannot have an MRI, in which case a CT scan is performed. This is to make sure that there is no obvious structural reason for the high pressure, such as a tumor. MRI may also provide some clues for the high pressure, but the MRI findings are not definitive.
2. Lumbar Puncture: This is a test to check CSF pressure. Please review the details of this procedure on the post titled, The Lumbar Puncture.
3. Visual field testing: This is done in ophthalmology office. It can be a useful way to monitor visual dysfunction, and indirectly, the severity of CSF pressure.
4. If a problem with venous sinus is suspected, an MRV or a CTV of brain is performed.
5. Other ophthalmological measures such as Optical Coherence Tomography (OCT), or Fluorescein Angiography may also help to rule out alternate optic nerve pathologies, or to assess the extent of nerve injury.

 

What are different causes of high CSF pressure?

 

A. Anything blocking the CSF-flow, like a tumor

B. Certain medications: such as minocycline, retinoids (vitamin A derivatives), and lithium

C. Corticosteroid withdrawal

D: Cerebral venous sinus thrombosis

E: Venous sinus compression by a mass, like a meningioma

F: Congenital stenosis or tightening of cerebral venous sinus

F: AVM (arteriovenous malformation or fistula) resulting in leakage of arterial blood (high pressure area) in a venous sinus (low pressure area).

 

Are there different levels of IIH?

Following division is based upon my own observations and experience:

            . Mild: CSF pressure 20-25 cm. In this range, patients may or may not have any symptom. An eye doctor on a routine eye examination may pick it up.

            . Moderate: CSF pressure 26-30 cm. In this range, patients usually complain of headaches.

            . Severe: CSF pressure: 31-40 cm. In this range, patients complain of continuous headache, blurred vision, and other symptoms described above.

            . Critical: CSF pressure >40 cm. In this range, patients usually have severe symptoms, including episodes of complete loss of vision, and quickly progressive visual loss. 

 

Who usually gets IIH?

Obesity is the most common factor, usually with history of recent and significant weight gain. Most patients are young women, but it may also affect men and children, and rarely older patients.

 

How is IIH treated?

The goal of treatment in IIH is to:

• Alleviate pressure to avoid permanent visual loss
• Alleviate symptoms
• Measures to prevent its recurrence.

 

Following measures can be useful, with some limitations:

1. Lumbar puncture (LP). It can help to confirm the diagnosis of high pressure, and remove some CSF to lower the pressure, at least temporarily.
2. Acetazolamide: a diuretic or a water-pill. It is a temporary solution until the more definitive measures start to work. Many patients do not tolerate its side effects, especially in higher doses where it is more effective.
3. Weight loss, in many cases the ultimate solution. Even 10% of weight loss can make a significant difference. For more difficult cases, bariatric surgery is an option.
4. Topiramate: It works similar to acetazolamide, though not that effective to lower CSF pressure. On the other hand, it may help to lose weight.
5. CSF shunting procedures: Usually, for patients not responsive to other measures, or with critically high CSF pressure. Shunting procedure involves putting a plastic tube with one end in the central brain cavity, and the other in the belly (the ventriculo-peritoneal shunting). It can also be achieved by putting a tube between the CSF cavity in the back and the belly (the lumbo-peritoneal shunt). Shunts can malfunction, get infected, or obstructed, and many times require replacement.
6. Eye surgery: In this procedure, an ophthalmologist performs a surgical procedure and approaches the back of the eye, from the side, and makes a hole in the covering of the optic nerve. This suddenly takes away the pressure on the optic nerve, with resolution of eye symptoms and the nerve protected from high-pressure injury. The procedure may have to be done on both sides. The risks may include injury to the optic nerve, other nerves in the vicinity, or the small blood vessels. It can be a useful option for patients with significant eye involvement, a permanent incurable reason (such as venous sinus disease), and not responsive to other measures.
7. Transverse sinus stenting: It is an option for some patients with venous sinus stenosis. Complications may include restenosis, blockage of the stent, and subdural hemorrhage.

Formal investigational data to compare different types of treatment is lacking, and the decision for the procedure is made based upon clinical experience and common sense. It depends upon the exact cause of high pressure, if known, severity of symptoms, and the extent of ophthalmological complications. IIH is best managed by close collaboration between a neurologist, an ophthalmologist (ideally a neuro-opthalmologist), and at times a neurosurgeon. Most patients require long-term follow-up and care.

 

Where can get more information about IIH?

American Academy of Neurology

American Ophthalmology Association