What Does a Brain MRI Check for Hemicrania Continua?

A brain MRI is a crucial step when you are evaluated for hemicrania continua. Hemicrania continua is diagnosed clinically based on your symptom history and a complete response to indomethacin. However, an MRI is used to rule out other problems. Even if your headache goes away completely with medication, an MRI is still recommended because other underlying medical issues can produce a similar pattern of symptoms and respond to the same treatment ^[1][2]. A normal MRI is generally a good sign, confirming that no dangerous underlying cause is to blame for the headaches.

When to Seek Immediate Care

An MRI is usually scheduled as a routine outpatient test. However, you should not wait for a scheduled scan if you experience warning signs of an emergency. Seek urgent medical care immediately if you have a sudden “worst-ever” headache, new weakness or numbness, trouble speaking, confusion, sudden vision loss or double vision, a new drooping eyelid, fever with neck stiffness, or a painful red eye.

What the Imaging is Looking For

A brain MRI checks for “secondary” causes of your headache—meaning the pain is a symptom of another structural or medical issue rather than a primary headache disorder. While these conditions are uncommon, it is standard practice to check for them. Depending on your symptoms, your doctor will order a specific combination of scans:

• Standard Brain MRI: This looks at the overall structure of your brain. It helps check for inflammatory conditions (like pachymeningitis, which is inflammation of the brain’s lining), severe sinus infections, or tumors that might be pressing on nerves ^[3][4][2].
• Vascular Imaging (MRA or MRV): A standard MRI does not fully evaluate your blood vessels. If your doctor suspects a vascular issue, they may add an MRA (Magnetic Resonance Angiography) or MRV (Magnetic Resonance Venography) ^[5]. These scans look for abnormalities like an aneurysm, a tear in a neck artery, or an abnormal connection between an artery and a vein ^[2][6][7].
• Dedicated Pituitary (Sellar) Views: The pituitary is a small, hormone-producing gland at the base of the brain in an area called the sella. While not universally required, dedicated pituitary views are often recommended when evaluating hemicrania continua ^[1]. Rare cases of pituitary tumors (such as a prolactin-secreting microadenoma) can cause headaches that resemble hemicrania continua ^[2][8]. These views are especially considered if you have hormonal changes, visual symptoms, or unusual autonomic symptoms (such as eye tearing, nasal congestion, or facial sweating). Keep in mind that many small pituitary growths are “incidental”—meaning they are found by chance and are not actually the cause of your headaches ^[2].

Do I Need Contrast?

Contrast is a gadolinium-based dye injected into a vein to make certain tissues, like blood vessels or areas of inflammation, show up more clearly. Contrast is not always mandatory, but it is frequently used to help detect tumors, infection, or inflammation ^[1][2]. Your doctor will choose the exact protocol (with or without contrast) based on your specific symptoms and neurological exam.

Planning for Your Scan: Practical Considerations

Kidney Function

Gadolinium contrast is filtered by your kidneys. If you have normal kidney function or mild to moderate kidney disease, standard modern contrast agents (known as Group II agents) are considered very safe, with an exceedingly low risk of a rare condition called nephrogenic systemic fibrosis ^[9][10]. Policies vary by imaging center—some require a recent kidney function blood test (eGFR), while others do not unless you have known risks ^[11][12]. Always disclose any history of kidney disease, acute illness, dialysis, or prior reactions to contrast, and follow the facility’s instructions for testing.

Medical Implants and Metal

You must tell the MRI facility about any metal in or on your body, including pacemakers, medication pumps, neurostimulators, aneurysm clips, cochlear implants, or a history of metal fragments (like shrapnel in your eye) ^[13][14][15]. You cannot assume a device is safe or unsafe; you must provide the exact make and model. Many modern devices are “MRI-conditional,” meaning they can be scanned safely if the facility uses specific settings and monitors the device ^[16][17]. Metal implants can also distort the MRI image, so specialized techniques may be used to get a clear picture ^[18].

Pregnancy and Breastfeeding

An MRI uses magnets and radio waves, not ionizing radiation like an X-ray or CT scan, and a scan without contrast can generally be performed safely during pregnancy when medically necessary. However, exposure to gadolinium contrast is avoided during pregnancy unless the expected diagnostic benefit outweighs any potential risks to the fetus ^[19][20][21]. Always inform the imaging team if you are or might be pregnant.

If you are breastfeeding, professional guidelines generally state that you do not need to interrupt breastfeeding or discard your milk after receiving gadolinium, as only a tiny amount passes into the milk ^[22][23]. Discuss any concerns with your doctor and follow the imaging center’s specific instructions.

What to Expect and Claustrophobia

An MRI typically takes 20 to 60 minutes depending on the specific scans ordered. The machine is a tube-like scanner that is very noisy; you will be given earplugs or headphones, a call button to communicate with staff, and you must remain very still.

If you are anxious about enclosed spaces, talk to your doctor ahead of time. Preparation can include relaxation techniques or requesting a “wide-bore” MRI machine that offers more space ^[24][25]. If your doctor prescribes a mild sedative to help you tolerate the exam, you must take it exactly as directed, you will need an adult escort to take you home, and you cannot drive or operate machinery afterward ^[25].