MRI Scan for Headaches and Migraines

Headaches and migraines affect around 10 million people in the UK. Most are harmless — tension headaches, dehydration, stress — but when headaches change in pattern, become unusually severe, or bring new neurological symptoms with them, a brain MRI is the best way to check for structural causes and put your mind at rest.

If you have had headaches for years with a stable pattern, imaging is rarely needed. But new headaches, worsening headaches, or headaches with features like weakness, visual changes, or seizures warrant a proper look inside.

Types of Headaches and When to Worry

Headaches fall into two broad categories: primary (the headache is the condition) and secondary (something else is causing it).

Primary Headaches

• Tension-type headaches — the most common type, affecting around 80% of people at some point. Often described as a tight band around the head, mild to moderate severity, both sides.
• Migraines — affect roughly 1 in 7 people in the UK. Typically one-sided, throbbing, moderate to severe. Often accompanied by nausea, light sensitivity (photophobia), sound sensitivity (phonophobia), and sometimes visual aura (flashing lights, zigzag lines) lasting 20-60 minutes before the headache starts.
• Cluster headaches — relatively rare (about 1 in 1,000 people), but extremely severe. Intense, one-sided pain around or behind the eye, lasting 15 minutes to 3 hours, occurring in bouts (clusters) over weeks or months. More common in men. Often accompanied by a red, watering eye and blocked nose on the affected side.
• Medication overuse headache — affects around 1-2% of the UK population. Caused by taking painkillers (especially codeine-containing medications) on more than 10-15 days per month.

Red Flags — When a Headache Needs Urgent Investigation

These features should prompt urgent medical assessment and usually imaging:

• Thunderclap headache — sudden, severe headache reaching maximum intensity within 60 seconds. This needs same-day investigation to rule out subarachnoid haemorrhage (brain bleed).
• New headache after age 50 — raises concern about temporal arteritis (giant cell arteritis), which can lead to permanent vision loss if untreated.
• Headache with fever and neck stiffness — possible meningitis or encephalitis.
• Progressive headache with neurological symptoms — weakness, speech problems, personality changes, or seizures.
• Headache worse on lying down or straining — possible raised intracranial pressure.
• Headache waking you from sleep — particularly between 1am and 5am.
• New headache in someone with cancer or HIV — needs urgent imaging.
• Headache after head injury — particularly if worsening.

What a Brain MRI Shows for Headaches

A brain MRI gives exceptionally detailed images of brain tissue, blood vessels, fluid spaces, and surrounding structures. For headache investigation, the radiologist will specifically look for:

• Brain tumours — both benign (meningiomas, acoustic neuromas) and malignant. Around 12,000 people are diagnosed with a brain tumour in the UK each year. MRI can detect tumours as small as a few millimetres.
• Aneurysms and vascular malformations — weak spots or tangles in blood vessels that could bleed. Unruptured aneurysms are found in about 3% of the general population.
• Chiari malformation — where the lower part of the brain (cerebellar tonsils) extends down through the base of the skull into the spinal canal. Affects about 1 in 1,000 people, often causing headaches made worse by coughing, straining, or bending forward.
• Signs of raised intracranial pressure — including idiopathic intracranial hypertension (IIH), more common in young women with higher BMI.
• White matter lesions — small bright spots on T2/FLAIR sequences. Can be seen in migraine sufferers (usually harmless) but also in multiple sclerosis, small vessel disease, and other conditions.
• Hydrocephalus — excess fluid in the brain's ventricles.
• Sinus disease — MRI picks up sinusitis incidentally, which may be causing or contributing to facial pain and headache.
• Previous stroke or bleeding — old infarcts or haemorrhages that may have gone unnoticed.
• Pituitary abnormalities — pituitary adenomas can cause headaches alongside hormonal symptoms.

MRI Sequences for Brain Imaging

A standard brain MRI protocol for headaches typically includes:

• T1-weighted — shows anatomy clearly. Grey matter appears grey, white matter appears lighter.
• T2-weighted — fluid appears bright. Good for detecting pathology.
• FLAIR (Fluid-Attenuated Inversion Recovery) — similar to T2 but suppresses the signal from spinal fluid, making small lesions near the ventricles and brain surface much easier to spot. This is the key sequence for white matter lesions.
• Diffusion-weighted imaging (DWI) — detects acute stroke (restricted water movement in damaged brain tissue).
• MRA (Magnetic Resonance Angiography) — images the blood vessels without contrast dye. Often added when there is concern about aneurysms or vascular malformations.

The scan typically takes 20 to 30 minutes without contrast, or 30-40 minutes if contrast and MRA are included.

What a Brain MRI Cannot Show

• The cause of most primary headaches — tension headaches and migraines do not show structural changes on MRI (apart from occasional non-specific white matter spots in migraine). A normal scan does not mean your headaches are not real — it means there is no structural cause, which is actually good news.
• Tiny aneurysms — MRA has a lower size limit of roughly 3mm. Very small aneurysms may be missed, though these are the least likely to rupture.
• Functional problems — MRI shows structure, not function. Issues like cortical spreading depression (the mechanism behind migraine aura) are not visible on standard MRI.
• Cervicogenic headache source — if your headache is coming from your neck, a brain MRI will look normal. A cervical spine MRI would be needed instead.

When NOT to Get a Brain MRI for Headaches

• Stable, long-standing migraines — if you have had the same migraine pattern for years with no new features, imaging is unlikely to show anything new and is not routinely recommended.
• Tension-type headaches responding to treatment — simple tension headaches that respond to over-the-counter painkillers and stress management rarely need imaging.
• Sinus headache — if your doctor suspects sinusitis, a CT sinus scan is quicker, cheaper, and more appropriate than MRI.
• First trimester pregnancy — MRI is generally deferred unless clinically urgent.

Alternative Diagnostic Approaches

• CT head — faster than MRI (5 minutes vs 20-30 minutes), available in all A&E departments. Used for urgent assessment of thunderclap headache, head injury, and stroke. Less detailed for soft tissue than MRI. Uses radiation.
• CT angiogram (CTA) — good for assessing blood vessels urgently, often used when subarachnoid haemorrhage is suspected.
• Lumbar puncture — measures spinal fluid pressure and can detect infection (meningitis) or bleeding not seen on scans. Used when raised intracranial pressure or subarachnoid haemorrhage is suspected despite normal imaging.
• Blood tests — ESR and CRP (for temporal arteritis), thyroid function (thyroid disease can trigger headaches), vitamin B12, iron studies (anaemia), and hormonal profiles.
• Eye examination — fundoscopy (looking at the back of your eye) can show papilloedema (optic disc swelling) caused by raised intracranial pressure.

What to Expect During Your Brain MRI

You will lie on your back on a padded table. Your head is placed inside a dedicated head coil — a frame that sits close around your head (it does not touch you) to improve image quality. The table then slides into the scanner bore.

For a brain scan, your entire head will be inside the tunnel. This is the part that some people find uncomfortable, so here are a few practical tips:

• Keep your eyes closed if the enclosed space bothers you — many people find this helps significantly.
• You will be given headphones or earplugs. The knocking and buzzing sounds vary in pitch and rhythm as different sequences run. Some people describe it as industrial machinery; others say it sounds like a drum and bass track.
• You will have a squeeze-ball alarm in your hand throughout — press it any time you need to stop.
• The radiographer can talk to you between sequences via an intercom.
• The scan room is air-conditioned and you will usually have a blanket.

Preparation

No special preparation is needed for a brain MRI without contrast. Eat, drink, and take your medications as normal. If contrast is being used, you may need a recent kidney function test (eGFR) and may be asked to fast for 2-4 hours beforehand. Remove all jewellery, hair clips, and piercings before the scan.

What Happens After Diagnosis — Treatment Pathways

• Normal MRI — reassurance that there is no structural cause. Your GP or neurologist can then focus on treating the headache type itself (migraine preventers, lifestyle changes, medication review).
• White matter lesions — if isolated and non-specific, these are often monitored. If multiple sclerosis is suspected, further tests (spinal MRI, lumbar puncture, evoked potentials) will be arranged.
• Brain tumour found — referral to a neurosurgeon and/or oncologist via the 2-week wait cancer pathway. Treatment depends on type, size, and location — options include surgery, radiotherapy, and chemotherapy.
• Aneurysm found — referral to a neurovascular team. Small unruptured aneurysms (under 7mm) are often monitored with annual MRA. Larger ones may need treatment (coiling or clipping).
• Chiari malformation — if symptomatic, referral to a neurosurgeon. Mild cases are monitored; severe cases may need decompression surgery.
• Raised intracranial pressure — referral to a neurologist. Treatment typically involves weight management, acetazolamide (a medication that reduces fluid production), and sometimes lumbar puncture or shunt surgery.

UK Statistics: Headaches and Migraines

• Migraine is the third most common disease worldwide
• Around 10 million people aged 15-69 in the UK experience migraines
• Migraine is 3 times more common in women than men
• The UK loses an estimated 25 million work and school days to migraine each year
• Only about 1 in 50 new-onset headaches is caused by a brain tumour
• Cluster headaches affect about 66,000 people in the UK
• The average time to receive a correct migraine diagnosis in the UK is 5 years

Private MRI vs NHS for Headaches

NHS waiting times for a non-urgent brain MRI typically range from 4 weeks to several months. During this wait, anxiety about undiagnosed headaches often makes symptoms worse — the worry itself can trigger more headaches.

A private brain MRI through Lola Health gives you:

• Fast access — appointments often available within 1-5 working days
• Self-referral — no GP referral needed
• Expert reporting — scans reported by specialist neuroradiologists
• Choice of location — 150+ centres across the UK
• Quick results — report typically within 3-5 working days

Related Blood Tests for Headaches

Blood tests can identify treatable causes that either trigger or worsen headaches:

• Thyroid function (TSH, Free T4) — both underactive and overactive thyroid can cause or worsen headaches. Thyroid disorders affect around 1 in 20 people in the UK.
• Vitamin B12 — deficiency is common and linked to migraines, particularly migraine with aura.
• Iron studies and full blood count — anaemia is an under-recognised cause of chronic headaches.
• ESR and CRP — important if temporal arteritis is suspected (typically over 50s with new temporal headache, scalp tenderness, and jaw pain on chewing).
• Vitamin D — emerging evidence links low vitamin D levels with increased migraine frequency.

Browse Lola Health blood tests

Frequently Asked Questions

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