Idiopathic Intracranial Hypertension (IIH) Ottawa Program

Intracranial pressure (ICP) refers to the pressure exerted by:

• Brain tissue

• Cerebrospinal fluid (CSF)

• Blood within the skull

In IIH, pressure is too high, even though brain imaging does not show a structural cause.

CSF is a clear fluid that:

• Cushions the brain and spinal cord

• Maintains normal pressure inside the skull

• Supports normal neurologic function

IIH is associated with:

• Female sex

• Overweight or obesity

• Recent weight gain

• Certain medications (e.g., vitamin A derivatives, some antibiotics)

• Hormonal factors

Not everyone with IIH has all risk factors.

Vision loss

• The most serious complication

• Can be gradual or sudden

• May be permanent if untreated

Chronic headache

• Headache may persist even after pressure improves

• Often overlaps with migraine

• Requires tailored headache management

A lumbar puncture (LP)—sometimes called a spinal tap—is a medical procedure used to measure the pressure of cerebrospinal fluid (CSF) and/or collect a small sample for testing.

LPs are commonly used in the evaluation of headache disorders such as idiopathic intracranial hypertension (IIH).

• The procedure is usually done with you lying on your side and relaxed. Positioning is critical as a seated position will yield unreliable results.

• The lower back is cleaned and numbed with local anesthetic

• A thin needle is inserted between the bones of the lower spine

• CSF pressure is measured using a spinal manometer (looks like a thermometer)

• A small amount of fluid is collected

• The needle is removed and a bandage is placed

The procedure typically takes 20–30 minutes.

What does it feel like?

• You may feel pressure during the procedure

• Sharp pain is uncommon after numbing medication is given

• Some people feel brief discomfort or an “electric” sensation if a nerve is irritated

Most people tolerate the procedure well.

After the procedure

• You may be asked to lie flat for a period of time

• Drink fluids as advised

• Resume normal activity gradually

• Mild back soreness is common and usually improves within a few days

Your care team will give specific instructions based on why the LP was done.

Common side effects

• Back soreness at the puncture site

• Headache, especially when upright

• Mild fatigue

These usually resolve on their own.

Post-dural puncture headache (PDPH)

Some people develop a post-dural puncture headache, which:

• Is worse when upright

• Improves when lying flat

• May occur within days of the procedure

This is a recognized complication and is treatable, often with conservative measures or an epidural blood patch if needed.

Less common complications

Rare complications include:

• Infection

• Bleeding

• Persistent nerve irritation

Serious complications are uncommon.

When to seek medical advice after an LP

Contact your care team if you experience:

• Severe or worsening headache

• Headache that does not improve with lying down

• Fever or signs of infection

• New weakness, numbness, or difficulty walking

• Severe or persistent back pain

An epidural blood patch is the most commonly used treatment for SIH.

What is a blood patch?

• A small amount of the patient’s own blood is injected into the epidural space

• The blood seals the leak and helps restore normal CSF pressure

Blood patches may be:

• Non-targeted (lumbar)

• Targeted to a known leak site

Some patients require more than one blood patch.

An epidural blood patch (EBP) is a commonly used and effective treatment for post dural puncture headache, CSF-leaks, and spontaneous intracranial hypotension (SIH). Understanding what is normal afterward can help reduce anxiety and guide recovery.

Common and expected effects

Many people experience temporary symptoms after a blood patch. These are usually mild to moderate and improve over days.

Common experiences include:

• Back soreness or stiffness at the injection site

• Neck tightness or pressure

• Headache that feels different from the original SIH headache

• A sensation of pressure or fullness in the head

• Fatigue or a “washed-out” feeling

These symptoms often reflect restoration of CSF pressure and tissue healing.

Rebound headache or “high-pressure” symptoms

Some people develop symptoms that feel opposite to SIH after a blood patch, sometimes called rebound intracranial hypertension.

This may include:

• Headache that is worse when lying flat

• Headache on waking in the morning

• Pressure behind the eyes

• Nausea

This is usually temporary and often improves with time and conservative measures. Your clinician can help guide management if this occurs.

Changes in headache pattern

It is common for headache to:

• Improve gradually rather than immediately

• Fluctuate from day to day

• Change in character as pressure normalizes

Improvement may take days to weeks, especially if symptoms were present for a long time before treatment.

Activity and recovery after a blood patch

General recommendations often include:

• Rest for the first 24 hours

• Avoid heavy lifting, straining, or vigorous activity for several days

• Gradual return to normal activity as tolerated

Specific instructions may vary depending on the type of blood patch performed.

When to contact your care team

Seek medical advice if you experience:

• Severe or worsening back pain

• New weakness, numbness, or bladder/bowel changes

• Fever or signs of infection

• Headache that becomes progressively severe or different from expected recovery

Acetazolamide is a medication commonly used to lower pressure around the brain by reducing the amount of cerebrospinal fluid (CSF) the body produces.

Acetazolamide works by:

• Reducing CSF production in the brain

• Lowering intracranial pressure over time

• Helping protect the optic nerves and vision

It does not directly treat pain, but by lowering pressure it can improve pressure-related symptoms and reduce the risk of vision loss.

• Taken by mouth

• Usually started at a low dose

• Dose is gradually increased as tolerated

• Sometimes accompanied with sodium bicarbonate if side effects develop

Many people experience some side effects, especially early on.

Common effects include:

• Tingling in fingers, toes, or around the mouth

• Fatigue or low energy

• Increased urination

• Altered taste (especially carbonated drinks)

• Nausea or stomach upset

These effects are often dose-related and may improve with time or dose adjustment.

Less common side effects can include:

• Electrolyte imbalances

• Kidney stones

• Low potassium levels