When Are Advanced Scans Needed for Hemicrania Continua?

Most people diagnosed with hemicrania continua will undergo a standard magnetic resonance imaging (MRI) of the brain to help exclude underlying structural issues ^[1][2]. However, advanced imaging like an MRA (magnetic resonance angiography), CTA (computed tomography angiography), MRV (magnetic resonance venography), or dedicated spine scans are not automatically required for everyone.

Your doctor will consider these specific scans if they suspect your headache is a “mimic”—a secondary headache caused by an underlying blood vessel problem, an infection, a tumor, a cerebrospinal fluid pressure disorder, or a structural issue in the neck ^[3][4]. They make this decision based on specific “red flag” symptoms, your personal medical history, and findings from your neurological physical exam ^[5].

Importantly, even if your headache completely goes away when you take indomethacin (the hallmark treatment for hemicrania continua), it does not definitively rule out a secondary cause ^[1][6].

Urgent Emergency Symptoms

Do not wait for an outpatient scan if you experience emergency symptoms. Seek immediate medical care if you develop:

• A “thunderclap” headache that reaches maximum intensity within seconds to minutes ^[7].
• New focal neurological deficits (localized problems with nerve, spinal cord, or brain function) like weakness, numbness, speech difficulty, confusion, or sudden vision loss ^[5][8].
• A new, painful drooping eyelid and small pupil (Horner syndrome) ^[9].
• A headache accompanied by fever, a stiff neck, or loss of consciousness ^[5].

In an emergency setting, the first test for a sudden severe headache is often a non-contrast head CT scan to check for bleeding, followed by other tests (like a CTA, MRI, or lumbar puncture) based on the timing and clinical findings ^[7][10].

Understanding the Different Types of Scans

When doctors order advanced imaging, they are choosing tools designed to look at specific structures. The choice between MRI/MRA and CT/CTA often depends on how urgently the scan is needed, kidney function, contrast allergies, and pregnancy status.

• Standard Brain MRI: Looks at brain tissue and structures. Does not use radiation. May use gadolinium contrast.
• MRA or CTA (Head and Neck Vessels): Looks specifically at the arteries (blood flowing to the brain). CTA uses radiation and iodinated contrast, making it very fast for emergencies. MRA does not use radiation and can often be done without contrast.
• MRV or CTV (Head Vessels): Looks at the veins (blood draining from the brain). Used to check for blood clots or pressure issues.
• Cervical Spine MRI or CT: Looks at the bones, discs, and spinal cord in the neck—this is different from looking at the blood vessels in the neck.

The Baseline Recommendation: Brain MRI

For anyone newly diagnosed with suspected hemicrania continua, medical guidelines recommend at least a standard brain MRI ^[1][2]. Depending on your specific symptoms, visual findings, or local protocols, your doctor may consider dedicated views of the pituitary gland (a small hormone-producing gland at the base of the brain), though this is not required for every patient ^[1][2].

A normal baseline MRI is reassuring, though it does not diagnose hemicrania continua on its own. If your symptoms remain stable and typical for hemicrania continua, repeat scans are generally not needed.

When an MRA or CTA is Considered (Arterial Scans)

An MRA or CTA of the head and neck is used to evaluate the arteries for conditions like an arterial dissection (a tear in the inner lining of a blood vessel), an aneurysm (a bulging weak spot), or reversible cerebral vasoconstriction syndrome (temporary narrowing of the blood vessels) ^[3][7].

Beyond emergency thunderclap headaches, arterial scans may be considered if you have:

• Severe neck pain or trauma: New or worsening headache accompanied by neck pain, especially if you recently had a neck injury or a forceful chiropractic neck manipulation ^[11][12].
• Partial Horner syndrome: A drooping eyelid (ptosis) and a constricted pupil (miosis) ^[9][13].
• New onset in older age: A brand new, daily headache starting after age 50 ^[5].
• Pulsatile tinnitus: Hearing a rhythmic whooshing or pulsing sound in your ear that matches your heartbeat. (This can be caused by arterial issues, venous issues, or pressure disorders, prompting your doctor to choose the appropriate targeted scan) ^[14].

When an MRV or CTV is Considered (Venous Scans)

An MRV or CTV is ordered to check the veins for cerebral venous sinus thrombosis (CVST, a blood clot in a brain vein) or issues related to high fluid pressure inside the skull, which can mimic the symptoms of hemicrania continua ^[4][15].

Venous imaging may be considered if you have:

• Papilledema: Swelling of the optic nerve at the back of the eye (seen during an eye exam), which indicates increased pressure around the brain ^[4][5].
• Vision changes: Double vision or a sixth-nerve palsy (an inability to move the eye outward) ^[16][17].
• High-risk factors for blood clots: A new, changing, or unusual headache if you are pregnant, recently gave birth, take estrogen-containing contraceptives, or have a known blood-clotting disorder or cancer ^[18][19].
• Specific positional changes: A headache that worsens significantly when you lie down (which can suggest high intracranial pressure, or high fluid pressure inside the skull). Conversely, a headache that worsens when you stand up may suggest low pressure, which requires a different diagnostic approach ^[5].

When Dedicated Spine Scans are Considered

If your doctor suspects your pain is cervicogenic (originating from the neck spine)—such as a pinched nerve or a structural spinal lesion—they may order an MRI or CT of the cervical spine ^[20]. Simple neck pain alone does not usually require a spine scan. Spine imaging is specifically targeted for patients who have focal tenderness in the spine, radicular symptoms (pain, numbness, or tingling shooting down the arm), significant trauma, weakness in the arms or hands, or a history of cancer ^[20][5].