Intracranial Hypertension

What is Intracranial Hypertension?

Intracranial hypertension is a condition where the pressure inside the skull is higher than normal. This increased pressure can place a lot of stress on the brain and other structures inside the head, possibly leading to a variety of neurological symptoms and complications. The symptoms can differ greatly from person to person, based on the underlying cause of the condition, the severity of the pressure increase, and individual health factors. Common symptoms can include intense headaches, problems with vision, feeling sick, vomiting, ringing in the ears, and in extreme cases, seizures or falling into a coma.

Diagnosing intracranial hypertension usually requires a mix of evaluating the patient’s health, results from advanced brain imaging procedures like CT scans and MRIs, and taking direct or indirect measurements of the intracranial pressure. It’s vital to identify and manage this condition quickly to prevent possible complications, including permanent damage to the nervous system and in some cases, even risk of death. Treatment usually depends on identifying the source of the problem, enhancing blood flow to the brain, and sometimes needing surgery to relieve brain pressure.

The volume inside a human skull is fixed, approximately holding around 1400 to 1700 milliliters. This volume is made up of around 80% brain tissue, and the remaining 20% is split equally between cerebrospinal fluid and blood.

The choroid plexus, a network of cells in the brain, has a crucial role in producing and regulating cerebrospinal fluid. It secretes around 20 milliliters per hour of cerebrospinal fluid, which is about 450 milliliters each day. This fluid is recycled, being reabsorbed and drained back into the bloodstream at about the same rate it’s produced. The production rate of cerebrospinal fluid changes with age, usually high during infancy, then gradually decreasing and stabilizing by adulthood. A pressure of the cerebrospinal fluid above 250 mm H2O in adults and 200 mm H2O in children generally indicates increased intracranial pressure.

The volume inside the skull stays more or less the same once the cranial sutures (the connections between skull bones) fully harden. If the volume of intracranial tissue or fluid increases, it can lead to increased intracranial pressure. This can happen when there are skull abnormalities, blockages in the brain’s ventricular system, or hematomas (accumulations of clotted blood). One of the critical parts of treating intracranial hypertension is in managing the risk of this increased pressure and making swift clinical decisions to prevent unwanted outcomes.

What Causes Intracranial Hypertension?

The brain’s volume is usually consistent in adults, but it can change due to things like growths in the brain or fluid buildup, known as cerebral edema. This fluid buildup can happen after events like severe brain injuries, big strokes, or a lack of oxygen to the brain. The amount of cerebrospinal fluid (CSF) and blood inside the brain changes often because they help regulate brain pressure.

Injuries to the brain, such as strokes or traumas, can disrupt the mechanisms that control the amount of CSF. If the production of CSF increases, as it can with a type of tumor called a choroid plexus papilloma, more CSF can be produced than reabsorbed. Similarly, if the reabsorption of CSF isn’t working well, as can happen after bacterial meningitis, it can also increase brain pressure. Conditions like blockages in the brain, birth defects that narrow parts of the brain, and sudden bleeding inside the brain can also cause interruptions in CSF drainage and lead to a condition known as hydrocephalus, or water on the brain.

The flow of blood in the brain (CBF) is primarily responsible for controlling how much blood is in the brain. Diseases that block blood from flowing out of the brain, like blood clots in the brain’s veins, pressure on the jugular vein, and changes to the structure of your neck caused by surgery, can cause blood to pool in the brain and increase brain pressure. There’s also a condition called Idiopathic Intracranial Hypertension (IIH), or pseudotumor cerebri, which is a long-term increase in brain pressure due to unknown reasons.

Increased brain pressure can be divided into primary and secondary causes. Here are some examples:

Primary causes come from inside the brain:
– Trauma that causes bleeding inside the skull, brain contusions
– Brain tumors
– Stroke
– Non-injury related bleeding inside the brain from things like blood vessel rupture
– Unknown reasons or benign increased brain pressure
– Hydrocephalus
– Meningitis
– Birth defects, including narrowing of parts of the brain, Dandy-Walker malformation (a certain type of birth defect of the brain), and Chiari malformation (where brain tissue extends into your spinal canal)

Secondary causes come from outside the brain:
– Breathing too slow, causing a lack of oxygen or too much carbon dioxide
– High blood pressure
– Blocked airway
– Metabolic issues, usually related to medications
– Seizures
– High fever
– Swelling in the brain due to high altitude
– Blockage of veins in the neck
– Interactions from multiple medications

Risk Factors and Frequency for Intracranial Hypertension

The likelihood of developing high pressure in the skull, also known as intracranial hypertension, depends on what’s causing it. Conditions that cause a rapid increase in pressure in the skull are more common in certain groups of people compared to conditions that slowly increase this pressure over time. For example, most spontaneous bleedings in the brain, around 60%, are due to high blood pressure. About a third of these bleedings happen in people over 80. Another common cause of spontaneous brain bleeding is amyloid angiopathy, which is more common in older people. Subarachnoid hemorrhage, a specific type of brain bleeding, happens in up to 91 out of 100,000 people each year, and most of the time it’s because of a ruptured aneurysm. In 2019, 27 million new cases of brain injury occured worldwide, with a range from mild to severe.

On the other hand, up to 90% of people with a slower, chronic increase in intracranial pressure are women who can still have children. Those with chronic high blood pressure or obesity are at a greater risk of developing high pressure in the skull. Out of 100,000 people, it happens to 1 person in the general population, 1.6 to 3.5 women, and 7.9 to 20 overweight women.

Signs and Symptoms of Intracranial Hypertension

Intracranial hypertension, or increased pressure in the skull, can result in a person becoming unconscious and experiencing difficulty breathing. Signs like this require immediate medical attention to help prevent the condition from escalating. After stabilizing the person, doctors ask questions to try and understand what could have caused the situation. Common symptoms can include headaches, changes in vision, nausea, and vomiting. Other effects might be nerve damage in the face and changes to mental state.

Looking into a person’s health history is also important in understanding why this could have happened. Certain factors, like being overweight, having high blood pressure or a thyroid disorder, or experiencing a head injury can make a person more likely to have increased pressure in the skull. Certain medications can also raise this risk.

High pressure in the skull can also be caused by idiopathic intracranial hypertension (IIH) or acute intracranial hypertension. IIH often leads to chronic headaches and worsening eyesight, which can sometimes result in permanent vision loss. On the other hand, acute intracranial hypertension, often caused by physical injuries, can produce symptoms like nausea, vomiting, confusion, and fatigue among others. This condition can also lead to brain herniation, a potentially fatal condition where the brain is squeezed out of position. Depending on the area affected, this can result in unconsciousness and difficulty breathing.

Physical examination can provide more details on the condition like the function of the eyes, ears, and face, balance, and mental wellbeing. Details doctors might look for include an enlarged blind spot in the field of vision (papilledema) or noticeable physical changes such as spontaneous bruising around the eye. Also, a condition called Cushing triad, which is characterized by slow heart rate, irregular breathing, and high blood pressure, could suggest that a person has intracranial hypertension. In infants, this condition can lead to physical changes like bulging fontanelles, which is the space between the bones of the skull that eventually fuse together as they grow.

Testing for Intracranial Hypertension

If a doctor suspects that someone has high pressure inside their skull, or intracranial hypertension, they will likely run a few different tests to confirm this and figure out what might be causing it. These tests may include imaging studies, a lumbar puncture, and an eye exam.

Imaging studies, like CT scans and MRIs, can take detailed pictures of the brain. They can find any structural problems, like tumors, and signs that the pressure is too high. CT scans are usually the first choice because they can quickly pick up acute conditions such as brain bleeds, growths, or fluid buildup in the brain. They’re also good at seeing if the brain’s ventricles are too large or if the grooves on the brain’s surface are getting too small. A type of CT scan called a CT venography can even check whether the veins in the brain are open and working properly.

MRIs are also helpful because they can pick up small issues that CT scans might miss, like little tumors or a condition called Chiari malformation. They can also see any problems with the flow of cerebrospinal fluid (CSF), which can increase pressure in the brain. If the doctor thinks there may be a problem with the veins in the brain, an MR venography can be done. This test can detect issues like narrowing of the veins or blood clots, which could lead to intracranial hypertension.

A lumbar puncture, or spinal tap, is a test where a small amount of CSF is taken from the lower back using a needle, to measure the pressure and check for abnormalities. In adults, a pressure reading over 20 millimeters of mercury suggests intracranial hypertension.

Other tests may be needed based on what the doctor thinks might be causing the problem. Cerebral angiography can spot abnormal blood vessels in the brain, CSF flow studies look at the CSF’s movement, and endocrine tests can catch hormonal disorders, like hypothyroidism or adrenal insufficiency.

Identifying the cause of high intracranial pressure requires a good clinical evaluation coupled with the above tests. If someone has idiopathic (meaning of unknown cause) intracranial hypertension, an MRI and lumbar puncture are typically performed. It’s important, though, to rule out potential intracranial masses through imaging before a spinal tap is done to avoid complications. If papilledema or swelling of the optic nerve due to high pressure inside the skull is suspected, referral to a neuro-ophthalmologist would likely be recommended for close monitoring.

Sometimes, high intracranial pressure can come on suddenly. In these instances, a CT scan of the head is usually conducted as a first step, alongside blood tests, to evaluate for infection, anemia, and electrolyte abnormalities. A ventriculostomy catheter, which measures pressure and can drain CSF, may be used in acute cases. If this isn’t possible, other tools that use microsensors and fibreoptic transducers can be implemented.

Treatment Options for Intracranial Hypertension

A significant sudden increase in intracranial pressure (ICP), or pressure inside the skull, is a medical emergency that needs close monitoring in an intensive care unit. The priorities in this situation are protecting the patient’s airway, maintaining stable vital signs, and preventing the condition from getting worse. It’s critical to keep a close watch on the patient’s heart rate, blood pressure, body temperature, breathing, oxygen levels, blood sugar, fluid balance, and heart rhythms. The ICP should also be monitored in patients who are suspected to have increased ICP, especially those with severe traumatic brain injuries.

Managing increased intracranial pressure is a four-step process, starting at Tier 0 and moving on to the next steps if the patient doesn’t show improvement. It includes raising the head of the patient’s bed to improve blood and cerebrospinal fluid flow, ensuring any neck brace isn’t obstructing blood flow, and managing the patient’s breathing to prevent further increases in intracranial pressure.

Finding ways to provide comfort for the patient is important, as stress and pain can raise blood pressure and ICP. Sedatives and painkillers that have the least effect on blood pressure should be used. Giving enough fluids is also key since dehydration can worsen the side effects of these medications. Fevers should also be controlled, as they can increase brain activity and blood flow, thereby raising ICP further. Conditions that cause fevers, like infections, should be ruled out.

Blood pressure may be high in patients with increased intracranial pressure, particularly traumatic brain injury patients. The blood pressure might be allowed to stay high in some patients because it can help maintain blood flow in the brain. However, if blood pressure needs to be lowered, beta-blockers and calcium channel blockers are often preferred. Medications that can further decrease blood pressure and increase blood flow in the brain, such as sodium nitroprusside, nitroglycerin, and nifedipine, are generally avoided.

If the ICP continues to rise despite these measures, medical therapies and surgical interventions may be needed. Drug therapies might focus on reducing brain swelling or suppressing brain activity. Surgically, removing any abnormal tissues that cause increased ICP, draining excess cerebrospinal fluid, or creating an opening in the skull to relieve pressure might be considered.

For patients with idiopathic intracranial hypertension (IIH), a condition of unknown cause that increases brain pressure, the focus is on managing the buildup of cerebrospinal fluid or improving blood outflow. Overweight patients would be advised to lose weight, as it can improve the condition. Medications to reduce the production of cerebrospinal fluid might also be given. Surgical treatment options typically include placing a shunt to divert excess cerebrospinal fluid, inserting a stent to improve blood flow, or performing an optic nerve sheath fenestration to relieve pressure on the optic nerve.

If you’re experiencing symptoms associated with high pressure inside your skull, it could be due to a number of different causes. Here are some conditions that could be causing your symptoms:

Damage to a nerve
An increase in skull pressure which doesn’t seem to have a specific cause (also known as “Pseudotumor cerebri”)
Problems with the blood supply to your brain, such as a stroke or hemorrhage (bleeding)
An excess buildup of cerebrospinal fluid in the brain (Hydrocephalus)
An infection in the protective layers surrounding the brain (Intracranial epidural abscess)
Bleeding inside the brain (Intracranial hemorrhage)
Cancer affecting the tissues surrounding the brain and spinal cord (Leptomeningeal carcinoma)
A slow-growing type of brain tumor called low-grade astrocytoma
Lyme disease, a tick-borne illness
A type of brain tumor called meningioma
Infection causing inflammation of the brain’s protective membranes (Meningitis)
Severe or recurring headaches often accompanied by nausea (Migraine)
Swelling of the optic disc due to increased pressure in or around the brain (Papilledema)
Bleeding in the space between the brain and the surrounding thin tissue (Subarachnoid hemorrhage)
Formation of a blood clot in the brain’s venous sinuses, preventing blood from draining out of the brain (Venous sinus thrombosis)

Proper evaluation and medical assessment by a doctor can help determine which of these conditions might be the cause of your symptoms.

What to expect with Intracranial Hypertension

The outcome for patients with increased pressure inside the skull (ICP) can vary greatly depending on its cause. This could range from fatal to harmless. Children usually have the ability to withstand higher ICP for longer periods of time.

A condition called Idiopathic Intracranial Hypertension (IIH) doesn’t usually increase the risk of death. However, surgical treatments could affect the risk of other health problems and even death. The outcome of this condition mainly relies on the health of a person’s vision. If optic nerve swelling, or disc edema, goes untreated, it could result in permanent damage to the optic nerve and loss of color vision.

For cases of temporary and acute increased pressure inside the skull, patients usually have a good outcome when they receive quick treatment. But, if treatment is delayed, or if the cause behind the condition is malignant, the prognosis is usually poor. Many surviving patients might develop permanent neurological issues later on.

Possible Complications When Diagnosed with Intracranial Hypertension

Complications of intracranial hypertension (increased pressure inside the head) can differ based on the root cause. These complications can include:

Stroke
Seizures
Damage to the optic nerve, known as optic neuropathy
Loss of vision
Stupor, or a state of near-unconsciousness
Coma
Respiratory arrest, which is when breathing stops

People with existing health issues should be advised to get medical help promptly if these symptoms develop and continue even after initial treatment.

Preventing Intracranial Hypertension

To prevent too much pressure in the skull, it’s important to address any factors that can be changed and also to generally take care of the health of the brain and eyes. Here are a few preventive steps one can take:

* Maintain a healthy weight, as this can lower the risk of too much pressure in the skull
* Regularly check your eyes to spot early any swelling of the optic nerve or other eye issues
* Manage medications like corticosteroids and contraceptive pills that could cause high pressure in the skull
* Manage other existing health conditions, e.g., stroke, which could cause too much pressure in the skull
* Avoid behaviors that can lead to traumatic brain injury (TBI)
* If the condition runs in the family, it can be helpful to seek genetic counselling

Patients with high pressure in the skull should also be made aware of the associated risks. These include the potential risk of loss of vision. If any changes in vision occur, they should see an eye specialist immediately.

Frequently asked questions

Intracranial hypertension is a condition where the pressure inside the skull is higher than normal.

Intracranial Hypertension is common in certain groups of people, with a range from mild to severe.

Signs and symptoms of Intracranial Hypertension include: - Unconsciousness - Difficulty breathing - Headaches - Changes in vision - Nausea - Vomiting - Nerve damage in the face - Changes to mental state In addition, there are specific signs and symptoms associated with idiopathic intracranial hypertension (IIH) and acute intracranial hypertension. IIH can lead to chronic headaches and worsening eyesight, which may result in permanent vision loss. Acute intracranial hypertension, often caused by physical injuries, can produce symptoms such as nausea, vomiting, confusion, and fatigue. It can also lead to brain herniation, which can cause unconsciousness and difficulty breathing depending on the area affected. Physical examination can provide further details on the condition, including the function of the eyes, ears, and face, balance, and mental well-being. Doctors may look for specific signs such as an enlarged blind spot in the field of vision (papilledema) or physical changes like spontaneous bruising around the eye. In infants, bulging fontanelles, which are the spaces between the bones of the skull, can be a sign of intracranial hypertension.

Intracranial Hypertension can be caused by various factors, including trauma that causes bleeding inside the skull, brain tumors, stroke, non-injury related bleeding inside the brain, unknown reasons or benign increased brain pressure, hydrocephalus, meningitis, birth defects, breathing too slow, high blood pressure, blocked airway, metabolic issues, seizures, high fever, swelling in the brain due to high altitude, blockage of veins in the neck, and interactions from multiple medications.

The doctor needs to rule out the following conditions when diagnosing Intracranial Hypertension: 1. Damage to a nerve 2. An increase in skull pressure which doesn't seem to have a specific cause (also known as "Pseudotumor cerebri") 3. Problems with the blood supply to your brain, such as a stroke or hemorrhage (bleeding) 4. An excess buildup of cerebrospinal fluid in the brain (Hydrocephalus) 5. An infection in the protective layers surrounding the brain (Intracranial epidural abscess) 6. Bleeding inside the brain (Intracranial hemorrhage) 7. Cancer affecting the tissues surrounding the brain and spinal cord (Leptomeningeal carcinoma) 8. A slow-growing type of brain tumor called low-grade astrocytoma 9. Lyme disease, a tick-borne illness 10. A type of brain tumor called meningioma 11. Infection causing inflammation of the brain's protective membranes (Meningitis) 12. Severe or recurring headaches often accompanied by nausea (Migraine) 13. Swelling of the optic disc due to increased pressure in or around the brain (Papilledema) 14. Bleeding in the space between the brain and the surrounding thin tissue (Subarachnoid hemorrhage) 15. Formation of a blood clot in the brain's venous sinuses, preventing blood from draining out of the brain (Venous sinus thrombosis)

The types of tests that a doctor would order to properly diagnose Intracranial Hypertension include: - Imaging studies such as CT scans and MRIs to take detailed pictures of the brain and identify any structural problems or signs of high pressure. - A lumbar puncture, or spinal tap, to measure the pressure of cerebrospinal fluid and check for abnormalities. - Eye exams to assess for papilledema or swelling of the optic nerve, which can be a sign of high pressure inside the skull. Other tests may also be needed based on the suspected cause of the condition, such as cerebral angiography, CSF flow studies, and endocrine tests. It is important to rule out potential intracranial masses through imaging before performing a lumbar puncture.

For patients with idiopathic intracranial hypertension (IIH), the treatment focuses on managing the buildup of cerebrospinal fluid or improving blood outflow. Overweight patients are advised to lose weight, as it can improve the condition. Medications to reduce the production of cerebrospinal fluid might also be given. Surgical treatment options typically include placing a shunt to divert excess cerebrospinal fluid, inserting a stent to improve blood flow, or performing an optic nerve sheath fenestration to relieve pressure on the optic nerve.

The side effects when treating Intracranial Hypertension can include stroke, seizures, damage to the optic nerve (optic neuropathy), loss of vision, stupor (a state of near-unconsciousness), coma, and respiratory arrest (when breathing stops).

The prognosis for Intracranial Hypertension can vary depending on the cause and severity of the condition. In cases of temporary and acute increased pressure inside the skull, patients usually have a good outcome when they receive quick treatment. However, if treatment is delayed or if the cause is malignant, the prognosis is usually poor. Many surviving patients might develop permanent neurological issues later on.

A neurologist or a neuro-ophthalmologist.