The space around the brain is filled with water-like fluid called liquor! If there is too much of this fluid present, the pressure around the brain rises. This can't be avoided because the space containing the fluid cannot expand.
Incidence
Idiopathic Intracranial Hypertension is a very rare condition. It mostly affects women, particularly obese women in pre-menopausal period, but can also occur in men and children. Studies of American-based populations have estimated that the incidence of pseudotumor cerebri ranges from 0.9-1.0 per 100,000 in the general population.
Possible causes of benign intracranial hypertension
Many conditions have been linked to high intracranial pressure. In fact, any disorder that blocks the flow of spinal fluid between the brain and its route to the blood, the jugular vein, can cause raised pressure. The exact causes for this condition are still unclear, but can often be associated with:
- menstrual problems,
- hormonal problems,
- being overweight,
- certain medications - oral contraceptive and vitamin A, as well as steroid withdrawal
Symptoms of pseudotumor cerebri
Some of the most common symptoms are:
Headaches (94%)
Headache is present in nearly all patients with Idiopathic intracranial hypertension and it is usually severe and present on a daily basis.
They are different from the headaches that healthy people may experience because they may awaken the patient and usually last for hours. They are commonly accompanied with nausea and patients often describe it as the worst head pain ever experienced.
Transient visual obscurations or blurring (68%)
Transient visual obscurations are episodes of transient blurred vision that usually last less than 30 seconds and are followed by full recovery of vision. Visual obscurations occur in about 3/4 of IIH patients. The attacks may involve one or both eyes. They are not correlated with the degree of intracranial hypertension or with the extent of optic nerve swelling. Visual obscurations do not appear to be associated with poor visual outcome.
Pulse synchronous tinnitus in the ear (58%)
Pulse intracranial noises or pulse-synchronous tinnitus is a very common symptom of intracranial hypertension. In patients with intracranial hypertension, compression of the jugular vein on the side of sound abolishes it.
Double vision (38%)
Patients who who experience double vision due to IIH most frequently complain of horizontal displacement of the images.
Other symptoms:
- Pain behind the eye (44%)
- Visual loss (30%)
- Pain with eye movement (22%)
- Shoulder and/or neck pain
- Vomiting
- Memory problems
- Migraine attacks with unexplained triggers
Risk factors for developing intracranial hypertension
Exogenous substances
Exogenous substances associated with idiopathic intracranial hypertension include:
- non-steroidal anti-inflammatory drugs (NSAIDs), tetracycline, nitrofurantoin, isotretinoin, tamoxifen, nalidixic acid, lithium, and the starting or stopping of steroids
- amiodarone,
- antibiotics,
- carbidopa,
- levodopa,
- chlordecone,
- corticosteroids,
- cyclosporine,
- danazol,
- growth hormone,
- indomethacin
Systemic diseases
The following diseases have been associated with idiopathic intracranial hypertension:
- anemia,
- chronic respiratory insufficiency,
- familial Mediterranean fever,
- hypertension,
- multiple sclerosis,
- polyangiitis overlap syndrome,
- psittacosis,
- Reye syndrome,
- sarcoidosis,
- systemic lupus erythematosus…
- Disorders of cerebral venous drainage
It is proven that venous compression by extra-vascular tumors or secondary thrombosis results in impaired absorption of the cerebrospinal fluid leading to pseudotumor cerebri.
Endocrine disbalances
Pregnancy is occasionally associated with idiopathic intracranial hypertension.
Secondary Intracranial Hypertension
While pseudotumor cerebri or primary intracranial hypertension is idiopathic, secondary intracranial hypertension always has a clear cause. Possible causes include:
- dural venous sinus thrombosis
- kidney failure
- leukemia
- lupus
- excess Vitamin A
- growth hormone treatments
- nasal fluticasone propionate
Diagnosis of pseudotumor cerebri
The diagnosis of intracranial hypertension is made by identifying the typical symptoms of the disease along with documentation of a high spinal fluid pressure.
Recommended blood tests are:
- Complete blood count
- Erythrocyte sedimentation rate
- Serum iron and iron binding capacity
- Anti-cardiolipin antibodies/lupus anticoagulant
- Antinuclear antigen (ANA) profile
Cerebrospinal fluid studies
- Opening pressure
- White blood cell and differential counts
- Red blood cell count
- Total protein
- Quantitative protein electrophoresis
- Glucose
- Aerobic bacterial culture and sensitivity
A CT scan, or MRI of the head and brain should be done although the result is usually normal. Sometimes the ventricles may appear smaller. The neurological examination is also normal except for the presence of swollen optic nerves called papilledema.
Treatment of pseudotumor cerebri
Treatment for patient with intracranial hypertension can be divided into:
- medical treatment
- surgical treatment
Medical treatment
Weight loss
The cornerstone of IIH medical treatment is weight loss. It may be the loss of fluid accompanying weight loss that is the significant factor but this has not been proven.
Even losing weight at a really slow pace may prove beneficial.
Fluid loss
Loss of fluid can also be obtained using diuretics (fluid pills).
Medications
Acetazolamide (Diamox ®) is the most commonly used medication. It is relatively safe but nearly all patients experience tingling of the fingers and toes as side effects. Patients may also notice that carbonated soft drinks taste metallic after using this medicine. Another diuretic commonly used that appears to be effective in some patients is Furosemide (Lasix®).
Corticosteroids are also very effective in lowering the intracranial pressure in those patients with idiopathic intracranial hypertension.
Surgical treatment
Optic nerve sheath fenestration
This procedure is based on surgeons making slits in the optic nerve sheath or covering. It is only used when patients do not respond adequately to medical therapy. The operation of fenestration is done first by an incision into the orbit. The eyeball is moved to the side and the optic nerve sheath is exposed. Slits or a large hole are then placed in the optic nerve sheath and fluid drains out, thereby taking pressure off the optic nerve.
Complications related to this procedure include:
- diplopia,
- optic nerve injury,
- vascular occlusion,
- a tonic pupil,
- the inherent risk of hemorrhage
- infection
Cerebrospinal fluid diversion procedures
Two neurosurgical interventions are highly effective in lowering the intracranial pressure: lumbo-peritoneal and ventriculo-peritoneal shunt. Lumboperitoneal shunts drain from the lumbar spine to the peritoneal cavity, while ventriculoatrial shunts run from the cerebral ventricles to the heart.
They represent the procedures of choice for treating patients with idiopathic intracranial hypertension who do not respond to maximum medical treatment. Unfortunately, these procedures have some complications.The most severe one is that some patients have periodic occlusion of the tubing with recurrence of symptoms and sometimes vision loss.
Appropriate diet
There is no doubt that weight reduction is definitely an important factor in the long-term management of these patients. Although As little as a 6% decrease in the total body weight can result in the resolution of papilledema. Unfortunately, weight loss in patients who are obese is difficult.
Preventing visual loss
Several researches have proven that the best way to prevent visual loss is to test vision regularly. Intracranial hypertension is a life-long disease but its’ symptoms are very treatable and, if treatment is started early enough, the vision loss is reversible.
Prognosis
The prognosis is good for most patients if they get an adequat treatment. This condition becomes chronic in rare cases only, and even then, long term medication may be sufficient to control the condition.