Idiopathic Intracranial Hypertension (IIH)
Pseudotumor cerebri: means “false brain tumor”. It is due to a buildup of pressure in the cerebrospinal fluid inside the skull. Symptoms of pseudotumor cerebri: include headache, nausea, vomiting, and pulsating sounds within the head, closely mimic symptoms of large brain tumors.
Pseudotumor cerebri can cause vision problems and severe headaches. Symptoms mimic those of a brain tumor, but no tumor is present.
Pseudotumor cerebri can occur in children and adults, but it's most common in obese women of childbearing age.
This condition is typically treated non-surgically through weight loss and medications. For severe cases of pseudotumor cerebri that don't respond to these treatments, surgery may be necessary.
Not a benign disorder. While once called benign intracranial hypertension, to distinguish it from secondary intracranial hypertension produced by a malignancy, it is not a benign disorder. Many patients suffer from intractable, disabling headaches, and there is a risk of severe, permanent vision loss, if left untreated.
As many as 10% of the people with pseudotumor cerebri experience progressively worsening vision and may eventually become blind. Even if your symptoms have resolved, they can recur — months or even years later.
Most Common Symptoms: however, not specific for IIH
- Headache (most common)
- Transient light flashes
- Intracranial noises (pulsatile tinnitus)
- Retrobulbar pain
- Sustained visual loss
Pseudotumor Cerebri Causes?
The exact cause of pseudotumor cerebri in most individuals is unknown, but it may be linked to an excess amount of cerebrospinal fluid within the bony confines of your skull.
Your brain and spinal cord are surrounded by cerebrospinal fluid, which acts like a cushion to protect these vital tissues from injury.
This fluid is produced in the brain and eventually is absorbed into the bloodstream. The increased intracranial pressure of pseudotumor cerebri may be a result of a problem in this absorption process.
In general, your intracranial pressure increases when the contents of your skull exceed its capacity. For example, a brain tumor typically increases your intracranial pressure because there's no room for it.
The same thing happens if your brain swells or if you have too much cerebrospinal fluid. Recent evidence indicates that the majority of people with pseudotumor cerebri have a narrowing (stenosis) in two large sinuses in the brain (transverse sinuses), but it's not clear whether the narrowing is a cause or effect of the condition.
Medical conditions associated with IIH:
■Polycystic ovary syndrome
■Underactive parathyroid glands
Medications that can cause this include:
■Discontinuation of steroids
■Excess vitamin A
Headache, often unusually severe, is the most common presenting sympton. The headaches are often lateralized and throbbing or pulsatile in character. They may be intermittent or persistent, daily in some, associated with nausea and vomiting in some.
In addition, a subset of patients describe headache exacerbation with changes in posture and some may report that relief occurs with nonsteroidal anti-inflammatory medications and/or rest.
Retrobulbar pain and pain with eye movement or globe compression are somewhat more specific features for IIH. In some patients, the pain follows a trigeminal or cervical nerve root distribution.
Neck stiffness is also commonly reported
Among younger children, headache is a less universal finding. In one series, 29% of children with IIH did not have headache, and men are less likely than women to note HA.
Transient visual obscurations: occur in about two-thirds of patients with papilledema. These last seconds at a time and can be bilateral or unilateral.
Position changes: Some patients note that these can be precipitated by changes in position (usually standing, but sometimes lying down or bending over), Valsalva, bright light, or eye movement.
The occurrence of transient visual obscurations does not appear to correlate with the degree of intracranial pressure elevation or the extent of disc swelling, and doesn’t predict future visual loss.
Photopsias, brief sparkles or flashes of light, can also occur in patients with IIH and, similar to visual obscurations, can be provoked by positional changes and Valsalva.
Pulsatile tinnitus is common in IIH and in the setting of headache is somewhat specific for the diagnosis. Patients often describe hearing rushing water or wind. This symptom can be persistent or intermittent and is believed to represent vascular pulsations transmitted by cerebrospinal fluid under high pressure to the venous sinuses.
Diplopia (Double Vision)
Patients with IIH may report intermittent or continuous horizontal diplopia.
On Exam — The most common signs of Pseudotumor Cerebri/IIH are:
- Visual field loss
- Sixth nerve palsy
Papilledema is optic disc swelling that is caused by increased intracranial pressure.
Normal optic disc Optic disc with papilledema
Papilledema is the hallmark sign of Pseudotummor Cerebri/IIH.
Severity of the papilledema relates to risk of permanent visual loss. Patients with more severe papilledema are at higher risk of permanent visual loss.
Loss of vision is the major morbidity in IIH and may be present on initial evaluation. Vision loss is usually gradual but can be abrupt. Such patients have a more fulminant course and more significant permanent vision loss.
- Visual field loss occurs before loss of acuity
confrontation visual fields are abnormal (nasal loss, temporal loss, visual blurring) in up to 32% at presentation.
Cranial nerve deficits are not uncommon with IIH and can resolve with IIH treatment.
How to Diagnose Pseudotumor Cerebri
Because the headache features are nonspecific, a thorough exam of the back of the eye (the fundus) is critical to identify patients with IIH. When papilledema is present, this suggests elevated intracranial pressure, which can have many etiologies in addition to IIH.
Secondary intracranial hypertension
Any entity that increases intracranial pressure may lead to papilledema. These include:
- Intracranial mass lesions (tumor, abscess)
- Increased cerebrospinal fluid (CSF) production, eg, choroid plexus papilloma
- Decreased CSF absorption, eg, arachnoid granulation adhesions after bacterial or other infectious meningitis, subarachnoid hemorrhage
- Obstructive hydrocephalus
- Obstruction of venous outflow, eg, venous sinus thrombosis, jugular vein compression, neck surgery
- Idiopathic intracranial hypertension (pseudotumor cerebri)
Diagnosis of Pseudotumor Cerebri or IIH is made according to specific, agreed-upon criteria:
The “Modified Dandy Criteria:
- Symptoms and signs of increased intracranial pressure (eg, headache, transient visual obscurations, synchronous tinnitus, papilledema, visual loss)
- No other neurologic abnormalities or impaired level of consciousness
- Elevated intracranial pressure with normal cerebrospinal fluid (CSF) composition
- A neuroimaging study that shows no etiology for intracranial hypertension
- No other cause of intracranial hypertension apparent
To exclude other possible causes your neurologist will take a complete history, including other medical conditions or medications.
In addition to seeing a neurologist, you will be referred to an experienced opthomalogist for a complete ocular exam which will document formal visual field examination, dilated fundus examination, and optic nerve photographs. Neuroimaging (MRI with contrast), will be done, followed by a lumbar puncture.
Pseudotumor cerebri treatment
Treatment typically begins with medications to control the symptoms. Weight loss is recommended for obese individuals. If your vision worsens, surgery to reduce the pressure around your optic nerve or to decrease the intracranial pressure may be necessary. Once you've had pseudotumor cerebri, you should have your vision checked regularly.
■ Glaucoma drugs. One of the first drugs usually tried is acetazolamide (Diamox), a glaucoma drug that reduces the production of cerebrospinal fluid by at least 50 %. Possible side effects: stomach upset, fatigue, tingling of fingers, toes and mouth, and kidney stones
■ Diuretics. If acetazolamide alone isn't effective, it's sometimes combined with furosemide, a potent diuretic that reduces fluid retention by increasing urine output.
■ Migraine medications. Medications typically prescribed to relieve migraines can sometimes ease the severe headaches that often accompany pseudotumor cerebri.
■ Optic nerve sheath fenestration. This procedure cuts a window into the membrane that surrounds the optic nerve. This allows excess cerebrospinal fluid to escape. Vision stabilizes or improves in more than 85% of cases. Most people who have this procedure done on one eye notice a benefit for both eyes. However, this surgery isn't always successful and may even increase vision problems.
■ Spinal fluid shunt. Another type of surgery inserts a long, thin tube — called a shunt — into your brain or lower spine to help drain away excess cerebrospinal fluid. The tubing is burrowed under your skin to your abdomen, where the shunt discharges the excess fluid. Symptoms improve for more than 80% of the people who undergo this procedure.
Weight loss is critical.
Obesity dramatically increases a young woman's risk of pseudotumor cerebri. In fact, a weight gain of as little as 5% of your body weight can increase the risk — even in women who aren't obese.
Losing extra pounds and maintaining a healthy weight may help reduce your chances of developing this potentially sight-stealing disorder.
[edited from mayoclinic.com and nimds.nih.gov]