What is Intracranial Hypertension?
Idiopathic intracranial hypertension (IIH) is a condition in which the cerebral spinal fluid (CSF) surrounding the brain is under higher than normal pressure. The increased pressure can cause swelling and damage to nerve tissue, especially the optic nerve. It can also result in the deformation of other parts of the brain, such as the pituitary gland and the sella turcica.
“Idiopathic” means that the condition doesn’t have an apparent cause. Some intracranial hypertension cases are caused by brain tumors, blood clots, drug reactions, or other disorders, but IIH doesn’t have a discernible cause.
The symptoms of IIH are often similar to symptoms of some types of brain tumors. Because of the similarity, the condition is sometimes called pseudotumor cerebri (meaning “false brain tumor”), but IIH is currently the more commonly used name.
Symptoms of Intracranial Hypertension
The most common symptoms of IIH include:
- Severe headaches, often directly behind the eyes
- Temporary total vision loss in one or both eyes
- Blind spots
- Loss of peripheral (side) vision
- Double vision
- Flashes of light in the field of vision
- Ringing or whooshing sound in the ears that pulses with your heartbeat
- Nausea and/or vomiting
- Neck pain
- Shoulder pain
What Causes Intracranial Hypertension?
The cause of idiopathic intracranial hypertension is not currently known. Several risk factors increase the risk of developing the disorder:
- Sex. Women are disproportionately affected by IIH. Men account for only 5% of cases.
- Age. Women are most likely to be affected between the ages of 20 and 50.
- Obesity. IIH is most common in people with a body mass index (BMI) greater than 30. A weight gain of 5-15% of total body weight also may put a person at greater risk, even if their final body weight is below the obesity threshold.
Secondary Intracranial Hypertension
In contrast to IIH, secondary intracranial hypertension can be linked to an underlying condition or cause. Common causes of secondary intracranial hypertension include:
- Reactions to antibiotics such as doxycycline, minocycline, or tetracycline
- Reaction to growth hormone
- Excessive vitamin A consumption
- Brain tumors
- Obstructive sleep apnea
- Systemic lupus erythematosus (SLE)
- Chronic kidney disease
- Polycystic ovary syndrome
- Blood-clotting disorders
Is Intracranial Hypertension Hereditary?
Scientists have not yet discovered a definite connection between IIH and genetics. However, in a small number of cases, IIH has been found in multiple generations of the same family. In these cases, no common underlying causes for the disorder can be identified, suggesting that there might be a genetic component to at least some rare cases of IIH.
How is Intracranial Hypertension Detected?
Early detection and diagnosis of IIH are essential for more than one reason. The symptoms of IIH are similar to those of potentially life-threatening conditions, so ruling out those conditions as soon as possible is vital. In some cases, IIH can cause rapid, permanent vision loss, and in these cases, early treatment may help prevent permanent damage.
IIH is often first noticed by optometrists, ophthalmologists, or general practitioners who identify swelling of the optic nerve (papilledema) during an eye exam. In many cases, the patient may not yet be experiencing any other symptoms when the papilledema is detected.
How is Intracranial Hypertension Diagnosed?
When a doctor suspects intracranial hypertension, they will work through a series of steps to confirm or rule out the diagnosis. The diagnostic process will usually include:
- Physical exam. This exam will focus on ruling out conditions other than IIH that could be causing the symptoms. The exam may also look for indications of an underlying cause of secondary IH.
- Neurological exam. This exam will test neurological functions such as reflexes, balance, muscle strength, and sensory perception. In the case of IIH, the exam is typically normal except for the visual symptoms.
- Vision tests. The doctor will conduct tests to look for papilledema, blind spots in the field of vision, and problems with peripheral vision.
- Imaging exams. Computerized tomography (CT) and/or magnetic resonance imaging (MRI) may be used to look for conditions, such as a brain tumor or brain injury, that may be causing the symptoms.
- Lumbar puncture (spinal tap). This test examines the cerebrospinal fluid for abnormalities and increased pressure.
PLEASE CONSULT A PHYSICIAN FOR MORE INFORMATION.
How is Intracranial Hypertension Treated?
The cause of IIH is not known, so no direct treatment for the disorder is available. Treatment programs typically include a combination of lifestyle changes and medication. In some severe, rapidly progressing cases, surgery may be required.
- Monitoring. Regular vision and eye exams will be recommended to watch for any worsening symptoms or progressive vision loss.
- Weight loss. Because IIH has been linked to obesity, doctors will usually recommend that obese IIH patients lose weight, and a low-sodium is also usually recommended. In cases where lifestyle changes don’t produce weight loss, weight-loss surgery may be recommended. Although weight loss does often correspond with an easing of symptoms, it does not always have an effect. Some patients report a recurrence of symptoms if they regain weight.
- Medication. The glaucoma drug acetazolamide helps to decrease the production of cerebrospinal fluid and, as a result, may help reduce the symptoms of IIH. Other diuretics, drugs that encourage fluid reduction by increasing urination, may also be prescribed.
Surgery is usually only recommended in cases where IIH is causing rapid deterioration of vision. Surgical interventions can include:
- Optic nerve sheath fenestration. This surgery attempts to decrease the pressure of the cerebrospinal fluid on the optic nerve. During the procedure, the surgeon makes an incision in the membrane that surrounds the optic nerve directly behind the eye. The opening allows fluid to drain away. The surgery carries the risk of making vision problems worse.
- Therapeutic shunting. This procedure involves inserting a long, thin catheter into the inner cavities of the brain. Excess fluid is allowed to drain through the tube, thereby decreasing pressure within the skull. This procedure is typically only considered when other treatments have been unsuccessful at relieving symptoms.
How Does Intracranial Hypertension Progress?
The progression of IIH varies widely from patient to patient. In some cases, the symptoms resolve on their own. Most cases respond well to treatment, and symptoms resolve within a few months. Sometimes the symptoms recur later. Most patients do not require surgery.
In about 5-10% of cases, the symptoms are progressive, and vision loss worsens over time. In a small number of cases, vision loss can be complete and permanent.
Although the symptoms may be severe in the worst cases, IIH does not typically lead to life-threatening complications.
How is Intracranial Hypertension Prevented?
Absent any definitive way to address the underlying cause of IIH, the best strategy for preventing the disorder is to manage its risk factors. Lifestyle changes that may decrease the risk of IIH include:
- Weight loss if you’re obese
- Avoidance of rapid weight gain
- Low-sodium diet
- Regular exercise
Intracranial Hypertension Caregiver Tips
Dealing with IIH can be an exhausting endeavor, both for the sufferer and their caregivers. Keep these tips in mind as you help your loved one to cope with IIH:
- Be empathetic. The symptoms of IIH are not outwardly visible, but they can be debilitating. Pain can make it difficult for your loved one to function, and the prospect of vision loss is terrifying for most people. Acknowledge what your loved one is going through, and offer any help you can.
- Be supportive. The prescribed treatment plan for IIH almost always involves radical changes to your loved one’s lifestyle. Making such changes is not easy for anyone, but they’re more manageable when you’re there to offer encouragement, support, and solidarity.
- Be an educator. Learn as much as you can about IIH (and your loved one’s unique experience of the disorder) so that you can help others to understand your loved one’s condition. There will likely be times when you have to be the one to communicate with healthcare providers, and you can best serve as your loved one’s advocate when you’re educated about the disorder.
Intracranial Hypertension Brain Science
Cerebrospinal fluid surrounds brain tissue, providing: protection from injury, nourishment for cells, and waste elimination. CSF is produced in the brain and, under normal conditions, is continuously reabsorbed by the body to maintain a constant pressure within the skull. In IIH, it appears that the normal process of reabsorption is disrupted, allowing excess fluid to build up in the skull. The cause and mechanism of the disruption remain unknown.
Some scientists believe that the strong connection between IIH, sex, and obesity suggests that hormones play a role in developing the disorder. Ongoing research is looking for trends in hormonal levels in IIH patients.
Other research focuses on the fact that IIH patients often have an abnormal narrowing of blood vessels in their brains. A surgical procedure called venous sinus stenting, which helps increase blood flow within the brain, has shown promise in treating IIH symptoms. However, it is unclear if the blood vessel abnormalities cause IIH or if the increased CSF pressure causes them.
Intracranial Hypertension Research
Title: Ocular Screening in Children and Young Adults at Risk for Increased Intracranial Pressure (ICP)
Study director: Sarah K. Jones
The purpose of this study is to evaluate the vision and posterior segment of the eyes in children and young adults less than 22 years of age with risk, suspicion, or past medical history significant for elevated intracranial pressure (ICP). Patients will have visual acuity and color vision tests. The posterior segment assessment will involve using a non-invasive (non-contact) imaging technique (i.e., a portable fundus camera in clinic and hospital settings).
Title: Non-invasive Diagnostic for Assessing Elevated Intracranial Pressure
Study Director: Eric Jackson, MD
Johns Hopkins University
The study is a prospective, multi-center, non-randomized, open-label observational study. This study aims to compare the accuracy of the EyeBOX to a clinical diagnosis of abnormal ICP as determined by an external ventriculostomy drain (EVD) or ventriculostomy catheter.
Title: Non-Invasive and Non-Contact Intracranial Pressure Waveform Recording Using Dynamic Video Ophthalmoscopy (ICP Waveform)
Study Director: Igor Nestrasil, MD, PhD
University of Minnesota
The monitoring of intracranial pressure (ICP) is crucial in head injuries and pathologies such as brain edema, arachnoid cyst, craniosynostosis, or, in very-low-birthweight infants, post-hemorrhagic hydrocephalus. Some current methods of ICP are invasive and, in the case of lumbar puncture, require anesthesia, which can distort the measurement by 5-10 mmHg. The golden clinical standard is direct measurement using a surgically-implanted intraventricular drain connected to an external pressure transducer (“ICP probe”). However, this method carries risks such as hemorrhage, malfunction, obstruction, or infection. The risk in pediatric patients is up to 5%, and in adults, the risk of fatal bleeding is 4-5% in patients with subdural and intraparenchymal monitoring devices. Due to these risks and the financial burden on patients, there have been attempts to develop non-invasive ICP estimation tools. This study will test the use of a video ophthalmoscope that will calculate the relative waveform of intracranial pressure and provide information about intracranial compliance without anesthesia, invasive methods, or contact with the eye.