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Each time we enter a doctor’s office, our arms are cuffed and blood pressure checked. It’s common knowledge that high or low blood pressure can cause a variety of symptoms, even leading to aneurysm or stroke. And yet, a large portion of the medical community (and likely an even larger portion of the general public) pays no heed to cerebrospinal fluid pressure. Whether you have a severe chronic illness, are mostly functional, have a spine or head injury, or no illness at all, please take a moment to learn about intracranial pressure and how it may be affecting you, along with millions of others, often without our awareness.
Cerebrospinal fluid (CSF) is a clear, watery fluid that surrounds the brain and spinal cord, providing protection, nourishment, and waste removal. The skull contains a closed system of brain, blood, and cerebrospinal fluid and a delicate balance must be preserved to maintain intracranial pressure (ICP).
When something goes wrong—with, for instance, the mechanisms that absorb or drain CSF, illness, or injury—pressure can increase inside the skull, and bone is unable to accommodate expansion. This elevated pressure is called intracranial hypertension.
The brain and spinal cord make up the central nervous system, which controls everything from thought, movement, and emotion to breathing, heart rate, body temperature, and hormone regulation. To prevent damage to the CNS and preserve those functions, the pressure and volume relationship between cerebrospinal fluid, the brain, and the vascular system inside the skull must be maintained.
High intracranial pressure can injure the brain or spinal cord, limit blood flow to the brain, or cause a myriad of symptoms including headache, vision issues, cognitive issues, mood issues, pain, and fatigue. Low intracranial pressure can cause an even larger variety. (Learn about intracranial hypotension and spinal CSF leaks here.)
Intracranial hypertension in adults is defined as intracranial pressure of 250mmH2O or above. But an opening pressure on a lumbar puncture may not always be a useful guide, as recent findings reveal that pressure can fluctuate. Positional changes, medication, or duration between spinal taps could also affect results. A normal opening pressure does not rule out intracranial pressure issues.
Because CSF pressure fluctuates, symptoms can fluctuate as well.
Acute IH can have a rapid, identifiable onset as the result of head injury/brain swelling or intracranial bleeding (aneurysm or a stroke) into the sub-arachnoid space surrounding the brain. In these cases, parts of the skull may be removed to accommodate the additional pressure.
Chronic IH is a neurological disorder in which CSF pressure remains elevated over a sustained period of time. Causes can include injury, illness, medication, stenosis, and much, much more. If the cause is unknown, it may be referred to as idiopathic intracranial hypertension (IIH) or if secondary to another cause, secondary intracranial hypertension (SIH). It was previously known as pseudotumor cerebri because it mimicked the symptoms of brain tumor, but the term is now out of use.
IH can be a lifelong condition, and may be mild, intermittent, or disabling.
Symptoms of intracranial hypertension vary. Not every person will have headache, or vision issues, or any of the less common side effects of high pressure. Assumptions otherwise is the reason many cases are misdiagnosed.
These symptoms may appear in a variety of patient groups, yet many do not realize they may be attributed to raised ICP. It's important to remember diagnoses considered rare can be disregarded because they are considered rare.
It is known that the longer a leak (low ICP) goes untreated, the less pronounced the orthostatic changes can become. Less clear is whether this also happens with high pressure cases, but it’s worth noting the signs may be clear at onset but more difficult to untangle over time.
It’s difficult to ignore the parallels between ICP disorders and other illnesses. The spinal CSF leak page gives insight as to how low intracranial pressure can mirror the symptom set of ME/CFS right down to PEM, and how some symptoms may only be relieved by pacing and rest (because being flat allows the CSF to resume its place the brain and may better allow for healing of a leak). With high intracranial pressure, the increased pressure can force cerebrospinal fluid into nerve root sheaths, causing severe nerve pain that can be relieved somewhat by gentle upright activity, as in fibromyalgia.
If nothing else, these similarities could be causing misdiagnosis, and intracranial pressure should be considered early on in the process. Elevated ICP is also regarded a factor in Long Covid, and it is difficult to deny the similarities between it and ME/CFS.
What's more, high intracranial pressure can be brought on by illness.
A few additional causes of increased intracranial pressure include:
CSF pressure issues may be aggravated by flow problems such as stenosis, drainage issues, or many things mechanical, and made worse by lax dura mater related to connective tissue disorders. CSF pressure may also cycle between high and low in some patients with underlying IH and spinal CSF leaks.
As with spinal CSF leaks, the mantra of positional symptoms applies (but here, in reverse).
Pressure issues may not be part of standard testing but simple at home observation can sometimes give major insight.
What does this experiment tell us?
→ If you feel better when you lie down and stay down, look into intracranial hypotension (low pressure) and leaks.
→ If you feel worse when you’re flat, look into intracranial hypertension (high pressure).
To diagnose IH, your doctor may start with a general exam or neurological exam, followed by imaging such as MRI and CT.
MRI findings may include flattening of the pituitary gland, which gives the appearance of an empty sella turcica. In addition, the sclera (white outer layer of the eye) at the back of the eye can appear flattened. Imaging may only be one of many tools your doctors use to determine your underlying cause. High pressure may be hereditary, depending on the underlying cause.
Importantly, lack of papilledema does not rule out intracranial hypertension.
Did you already have a lumbar puncture and felt relief? This may indicate high intracranial pressure. If you did not eventually resume your baseline afterward, or felt substantially worse over the following days or months, this may indicate low pressure due to a leak, or you may already have been leaking. (If so, check out the spinal CSF leak page.)
Chiari and Brain Sag—Congenital, leak, or downward pressure?
According to studies, over time IH may cause an acquired Chiari malformation. Acquired Chiari (or brain sag) may also be the result of low fluid, such as CSF leaks, or LP shunts or multiple spinal taps. As noted on the spinal CSF leaks page, pressure on the brainstem and cranial nerves can affect function of the central nervous system and lead to a variety of symptoms.
Per the IHR Foundation, research suggests acquired Chiari malformation is eight times more common in chronic IH patients who have not had shunting procedures. Find out more at: https://ihrfoundation.org/what-is-ih/ih-and-related-disorders
As with leaks, it is essential to find a specialist experienced in pressure issues and armed with the most current information. Don’t let the incorrect notion that pressure issues are rare prevent you from finding treatment. If you fit the profile and your physician dismisses the possibility, consider a second opinion with an experienced specialist.
The official ICP diagnosis criteria can be found here https://ihrfoundation.org/what-is-ih/diagnosis
To treat IH, intracranial pressure must be lowered. As with leaks, treatment can often be completed in a relatively easy manner. Carbonic anhydrase inhibitors can reduce spinal fluid, including Diamox (acetazolamide) and the less potent Lasix (furosemide), Topamax (topiramate), and Neptazane (methazolamide).
It is important to understand that while lumbar punctures, or spinal taps, may temporarily ease IH symptoms, spinal fluid regenerates at a rate of .3cc per minute. The body produces, absorbs, and replenishes the total CSF volume several times each day. And, as many well know, lumbar punctures carry the risk of creating a CSF leak that may worsen a person’s condition considerably. Neurosurgical shunts are an option in certain cases but also carry more risk.
Tips for coping with IH in addition to or outside of medical intervention
Questions to consider as, no matter one's condition, pressure may affect them in ways they may not have realized. Even the relatively healthy can be affected by pressure changes and these may help you notice when and how your symptoms occur.
Think about how these factors affect your symptoms. If you believe you have a spinal CSF leak or IH, discuss it with your care team.
Intracranial Hypertension Research Foundation (information on IH) https://ihrfoundation.org/what-is-ih
Spinal CSF Leak Foundation Physician Directory (doctors experienced in intracranial pressure issues) https://spinalcsfleak.org/directory/
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