Increased Intracranial Pressure

What is Increased Intracranial Pressure?

Intracranial hypertension (IH) is a medical condition where there’s an increase in the pressure within your skull. This pressure is measured using units called ‘millimeters of mercury’ (mm Hg), and typically, it should be less than 20 mm Hg.

Your skull, also referred to as the cranium, is a solid structure that houses the brain, a fluid called cerebrospinal fluid, and blood. If the amount of these contents inside your skull surges, then it will cause an increase in the pressure. This increase can cause problems because according to a principle called the Monroe-Kellie Doctrine, the total volume of these three contents remains uniform. So, if one component increases, it will result in the decrease of one or both of the others — this can lead to less blood flow to your brain or a dangerous condition known as brain herniation, which is the shifting or squeezing of brain parts.

Cerebrospinal fluid (CSF) is a clear fluid found in certain spaces and cavities in your brain and spinal cord, called subarachnoid spaces and ventricles. It acts like a cushion to protect your brain and spinal cord. This fluid is produced in your lateral ventricles, by a structure known as the choroid plexus. This CSF then moves to the third ventricle through the Monroe opening. It then flows to the fourth ventricle via the Sylvius aqueduct. From there, the CSF flows into the subarachnoid space through openings known as Magendie and Luschka. Eventually, it gets absorbed back into the blood through structures known as arachnoid granulations in the dural venous sinuses.

What Causes Increased Intracranial Pressure?

The causes of excess pressure inside your skull, or what doctors call “increased intracranial pressure” (ICP), can be grouped according to what parts of the brain are causing the pressure:

1. Increase in Brain Size

Your brain can swell up or grow larger from many causes, such as head injuries, stroke, certain medical conditions, and some medications.

2. Presence of Mass or Growth

There could be something taking up space inside your skull. For instance:

* A hematoma, which is a collection of blood outside of the blood vessels.
* A tumor, which is a growth of abnormal cells.
* An abscess, or a pocket of pus.
* An infarct, a tissue that’s dead due to lack of blood supply.

3. Too Much Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in your brain and spinal cord. It’s produced within the ventricles of the brain but can increase because of:

* Increased CSF production due to a tumor in the choroid plexus (The choroid plexus is tissue in the brain that produces CSF)

4. Poor Drainage of Cerebrospinal Fluid

Sometimes CSF isn’t drained or absorbed properly. This can happen because of:

* A condition called obstructive hydrocephalus.
* Inflammation or small nodules in the meninges, which are the membranes covering the brain and spinal cord.

5. Increase in Blood Volume

The blood flow to the brain can increase due to:

* High levels of carbon dioxide in the blood.
* A bulging blood vessel, or aneurysm.
* Slow or stagnant blood flow from blood clots in the veins or high pressure in the veins due to heart failure.

Other causes

Less common reasons for increased intracranial pressure include:

* A condition with no known cause, called idiopathic or benign intracranial hypertension.
* Deformed skull shapes, such as craniosynostosis, a condition where the parts of a baby’s skull join together too early.
* Too much vitamin A or use of the antibiotic tetracycline.

All the above can lead to increased pressure inside the skull. If you are showing symptoms, it is crucial to see a doctor for an evaluation.

Risk Factors and Frequency for Increased Intracranial Pressure

The exact number of cases of intracranial hypertension, which is increased pressure in the skull, is not currently known. However, the Centers for Disease Control and Prevention states that in 2010, 2.5 million people suffered from a brain injury, which can often lead to this condition. It is recommended that all patients with severe brain injuries be monitored for this. Studies suggest that the rate at which people contract idiopathic intracranial hypertension, a specific type of this condition, is between 0.9 to 1.0 per 100,000 people. This is particularly common in women who are overweight.

Signs and Symptoms of Increased Intracranial Pressure

If a person shows certain signs and symptoms, it could indicate that they have high pressure inside their skull, also known as intracranial hypertension. These symptoms include headaches, vomiting, mental changes that can range from sleepiness to coma, and various visual problems. Visual issues could include blurred vision, seeing double due to nerve issues, sensitivity to light, swelling of the optic disc (the area where the optic nerve connects to the eye), and eventually damage to the optic nerve. Babies who still have a soft spot on their skull might have a protruding bump over that area.

There’s also a condition called “Cushing’s triad”, which is a mix of three symptoms: high blood pressure, slow heartbeat, and irregular breathing. This condition is a sign that the brain may be starting to push down into the spinal cord due to this high pressure in the skull. This dangerous condition is known as herniation. High blood pressure happens as a reflex to keep blood flowing to the brain, but this leads to a slow heartbeat and changes in breath due to the high pressure affecting the brain stem. If untreated, herniation could be fatal.

Testing for Increased Intracranial Pressure

If your doctor suspects that you have increased intracranial pressure (ICP) – which means the pressure inside your skull is higher than normal, it is crucial to get a detailed personal medical history, a thorough physical examination, and more tests to confirm.

It’s critical to find and address high ICP as soon as possible to prevent harmful and potentially lethal complications, such as brain herniation – when brain tissue, cerebrospinal fluid, and blood vessels are moved away from their usual position in the skull. This condition is often associated with a severe type of stroke mostly seen in younger people, called malignant middle cerebral artery stroke. Patients with this condition are often cared for in the Intensive Care Unit (ICU). The key to managing this is to keep a very close eye on any neurological changes. These might include changes in consciousness or the onset of unusual pupil reaction.

If your doctor suspects a brain issue, you will likely need a CT scan (a special type of X-ray) of your brain. This can show any swelling (also known as edema) as low-density areas and blurred lines between the brain’s grey and white matter. The scan may also show a loss of the brain’s natural cavities (sulci and ventricles) – both of which suggest increased ICP. Your doctor will perform serial CT scans to monitor whether edema is getting better or worse over time.

A physical exam of the back of your eye (fundus), might show a condition called papilledema. This is when the optic disc in your eye is swollen due to increased pressure in or around the brain. The optic disc usually appears pink or red, but in papilledema, it looks more prominent and pale, indicating a rise in ICP.

The doctor may also order either a CT scan or an MRI (a test that uses strong magnets to create detailed images of organs) of your head to look for signs of increased ICP, such as enlarged brain cavities (ventricles), any unusual shifting of the brain, or abnormal mass-like structures that may be due to tumors, abscesses, or blood clots.

A lumbar puncture, also known as a spinal tap, involves inserting a needle into the space around your spinal cord to measure the pressure of your cerebrospinal fluid (the fluid that surrounds your brain and spinal cord). Any measurement above 20 mm Hg indicates high ICP. But before even doing this test, imaging of the brain should be done to prevent any sudden unwanted brain shift that might occur due to a rapid decrease in the pressure after the lumbar puncture.

There are several devices that your doctor might use to continually monitor your ICP. One of these involves placing a special type of sensor (a fiber optic catheter) into the brain tissue to directly measure the pressure there.

Your doctor could also insert a drain directly into the ventricles of your brain (the fluid-filled spaces in the brain). This drain can be attached to a device that measures pressure (a manometer) to give a reading for the pressure in your brain’s ventricles.

More recently, doctors have started using ultrasound technology to measure the diameter of the sheath (covering) of the optic nerve. This is considered a new way of figuring out if you have high ICP. In this procedure, they measure the thickness of the optic nerve’s covering in each of your eyes, and they normally do this 3 mm behind the eyeball. The cut-off values to denote high ICP usually range between 0.48 cm to 0.63 cm.

Treatment Options for Increased Intracranial Pressure

In general, managing a patient’s airway and ensuring that they are breathing and have proper circulation should always be the first priority. The main areas to focus on during treatment include maintaining proper blood flow to the brain, treating the underlying cause of the issue, and lowering the pressure inside the patient’s skull (a condition known as intracranial pressure).

There are several techniques to lower intracranial pressure. These include raising the patient’s head so it’s more than 30 degrees above their body, keeping their neck straight to allow proper drainage of blood from the head, and ensuring that the patient’s blood carbon dioxide levels stay around 30 mm Hg, which could be achieved through controlled breathing.

Mannitol, a substance that can draw fluid out of the brain, can be used to decrease swelling in the brain. While it’s primarily used to decrease the thickness of the blood, it can also reduce blood volume. However, potential side effects include dehydration and kidney damage. Diuretics, drugs that help your body get rid of unneeded water and salt through urine, can also be used to reduce pressure in the brain.

Doctors may give the patient a 3% saline solution either as a single large dose or continuous infusion to decrease swelling in the brain, closely monitoring blood sodium levels. This treatment is typically safe until blood sodium levels exceed 160. In some cases, medications such as acetazolamide, are used to reduce the production of cerebrospinal fluid (CSF), the clear, colorless body fluid found in the brain and spinal cord. CSF can also be drained with a lumbar puncture, which also helps diagnose conditions.

If a patient has chronic high brain pressure that might lead to blindness, a surgical procedure known as optic nerve fenestrations can be performed, where tiny holes are made in the optic nerve to relieve the pressure. A procedure known as decompressive craniectomy may be considered as a last resort. This involves the removal of part of the skull to allow the brain to swell without restriction. Other treatments like glyburide, a medication that stops the receptors that can contribute to swelling in stroke patients and barbiturates, a type of sedative, are also sometimes used to lower intracranial pressure.

When experiencing certain symptoms, there could be several possible medical conditions causing them. Here are some that might be considered:

Acute nerve injury
Blood dyscrasias and stroke
Hydrocephalus
Intracranial hemorrhage
Intracranial epidural abscess
Lyme disease
Meningioma
Migraine variants
Subarachnoid hemorrhage

What to expect with Increased Intracranial Pressure

The outcome of a condition largely depends on its root cause and severity. In the case of benign intracranial hypertension, which is basically an increase in the pressure inside your skull, it doesn’t increase the risk of death by itself. What can potentially increase the death rate is extreme obesity, which is often linked with this condition.

Another important thing to remember is that a significant issue associated with intracranial hypertension is visual loss, which means it can lead to serious eye and vision problems.

Preventing Increased Intracranial Pressure

Patients who are at risk of developing increased pressure inside their skull need to be aware of warning signs. These signs include persistent headaches and vomiting. By understanding these symptoms, they can seek medical attention promptly if needed. The pressure increase we’re referring to is a potentially dangerous condition often caused by a brain injury or a condition like a tumor.

Frequently asked questions

Increased Intracranial Pressure (ICP) is a medical condition where there is an increase in the pressure within the skull. This pressure is typically measured in millimeters of mercury (mm Hg) and should be less than 20 mm Hg.

The exact number of cases of intracranial hypertension is not currently known.

Signs and symptoms of Increased Intracranial Pressure include: - Headaches - Vomiting - Mental changes ranging from sleepiness to coma - Various visual problems - Blurred vision - Seeing double due to nerve issues - Sensitivity to light - Swelling of the optic disc - Damage to the optic nerve - Protruding bump over the soft spot on the skull in babies Additionally, there is a condition called "Cushing's triad" which consists of three symptoms that indicate increased intracranial pressure: - High blood pressure - Slow heartbeat - Irregular breathing If these symptoms are present, it may be a sign that the brain is starting to push down into the spinal cord, which is a dangerous condition known as herniation. If left untreated, herniation can be fatal.

The causes of increased intracranial pressure can be grouped into several categories, including an increase in brain size, the presence of a mass or growth, too much cerebrospinal fluid, poor drainage of cerebrospinal fluid, an increase in blood volume, and other less common reasons such as idiopathic or benign intracranial hypertension, deformed skull shapes, and certain medications.

The doctor needs to rule out the following conditions when diagnosing Increased Intracranial Pressure: 1. Acute nerve injury 2. Blood dyscrasias and stroke 3. Hydrocephalus 4. Intracranial hemorrhage 5. Intracranial epidural abscess 6. Lyme disease 7. Meningioma 8. Migraine variants 9. Subarachnoid hemorrhage

The types of tests needed for Increased Intracranial Pressure (ICP) include: 1. CT scan or MRI of the brain to look for signs of increased ICP, such as swelling, shifting of the brain, or abnormal mass-like structures. 2. Physical exam of the back of the eye (fundus) to check for papilledema, which is swelling of the optic disc due to increased pressure in or around the brain. 3. Lumbar puncture (spinal tap) to measure the pressure of the cerebrospinal fluid surrounding the brain and spinal cord. 4. Insertion of a special sensor (fiber optic catheter) into the brain tissue to directly measure the pressure there. 5. Insertion of a drain into the ventricles of the brain to measure the pressure using a manometer. 6. Ultrasound measurement of the diameter of the sheath of the optic nerve to determine if there is high ICP. 7. Serial CT scans to monitor changes in brain swelling over time. These tests help diagnose and monitor increased ICP and guide treatment decisions.

Increased Intracranial Pressure can be treated through various techniques. These include raising the patient's head, keeping their neck straight, and controlling their blood carbon dioxide levels. Mannitol can be used to decrease brain swelling, while diuretics can help reduce pressure in the brain. A 3% saline solution may be given to the patient, and medications like acetazolamide can be used to reduce the production of cerebrospinal fluid. In some cases, surgical procedures such as optic nerve fenestrations or decompressive craniectomy may be considered. Other treatments like glyburide and barbiturates are also sometimes used to lower intracranial pressure.

When treating Increased Intracranial Pressure, there are several potential side effects to consider. These include: - Dehydration and kidney damage from the use of Mannitol, a substance that draws fluid out of the brain. - Imbalance in blood sodium levels when using a 3% saline solution, which may require close monitoring. - Potential side effects from diuretics, such as increased urination and electrolyte imbalances. - Side effects from medications like acetazolamide, which can include nausea, vomiting, and electrolyte imbalances. - Risks associated with lumbar puncture, including headache, infection, and bleeding. - Risks associated with surgical procedures like optic nerve fenestrations and decompressive craniectomy, which can include infection, bleeding, and complications related to the brain and nervous system. - Side effects from medications like glyburide and barbiturates, which can include drowsiness, dizziness, and changes in blood pressure. It is important to closely monitor patients for these side effects and adjust treatment as necessary to minimize risks.

The prognosis for increased intracranial pressure largely depends on its root cause and severity. Benign intracranial hypertension, which is an increase in pressure inside the skull, does not increase the risk of death by itself. However, extreme obesity, which is often linked with this condition, can potentially increase the death rate. Additionally, intracranial hypertension can lead to serious eye and vision problems, which is an important issue associated with this condition.

A neurologist or a neurosurgeon.