In addition to being painful and a debilitating interruption for busy adults, migraines can be a seemingly insurmountable frustration. You can identify and eliminate triggers, meditate and deep breathe the mornings and nights away, and yet they still come back.
Wouldn't it be nice if migraines were like broken bones - easy to diagnose on an X-Ray and straightforward to fix? Unfortunately, it's not that easy and, while imaging tests such as MRIs can provide helpful information, they aren't able to "show us" the migraine.
Why Are MRIs Used to Investigate Migraines?
Before going into exactly why an MRI is used as an investigative tool, rather than a diagnostic tool, it's important to understand exactly what it does. MRIs are at type of "imaging test," which means they provide a picture of the brain for your doctor to review.
Magnetic Resonance Imaging (MRI) does not use any radiation (unlike x-rays or CT scans). Rather, the combined work of a large magnet, radio waves and a computer to form clear imagines of the soft organs and tissues in the body. MRIs are the best way to obtain a clear image of the brain, providing greater insight into its structure and biochemistry. An MRI provide more defined images than CT scans, particularly when it comes to the back portion of the brain and the neck-level area of the spine.
For this reason, MRIs are often used by doctors and neurologists to investigate their patients' migraines. However, in all but a very few cases, the imaging test won't actually tell what is causing the migraines.
Primary & Secondary Headaches
What an MRI is able to diagnose are secondary issues that may cause or contribute to migraines. This is where things can become a bit confusing. In the world of headaches, there are two different types:
- Primary headaches. These are the most common type of headache. Primary headaches are diagnosed based on the way they express themselves in the body. Examples include migraines, tension and cluster headaches. They are considered, "idiopathic," a medical term for conditions that arise with no known cause. In other words, MRIs performed for primary headaches almost invariably yield "normal" results - they don't show any biologic or physiologic reason for the headaches.
Primary headaches often:
---Occur in patients throughout their life.
---Have known triggers.
---Begin after certain activities such as exercising, drinking, coughing or
working on a computer.
---Occur in patients who have a family history of headaches.
- Secondary headaches. Secondary headaches are much less common than primary headaches. They are caused by a specific, diagnosable, underlying condition. Examples of secondary headaches would be those caused by an original head injury, tumor, vascular disease, stroke, or an infection.
Secondary headaches typically manifest differently than primary headaches. They usually:
---Occur in individuals younger than 5 and over the age of 50.
---Come on suddenly, with little warning, in those who do not normally suffer from headaches.
---Include additional symptoms such as fever, optic nerve swelling, neurological abnormalities or deficits.
---Are determined by an abnormal neurological examination
An MRI can be helpful in diagnosing the cause of secondary headaches, which may also be the underlying cause of a primary headache.
This places doctors in a difficult position. While they know via research that MRI tests rarely reveal helpful information for patients suffering from migraines, there is always the very slight chance that an imagine test could reveal something. In addition to wanting to provide the best treatment for their patients, doctors will prescribe MRIs in order to avoid litigation in case that patient happens to be the rare exception.
What The Evidence Says Regarding MRI and Migraines
In an article published in the Expert Review of Neurotherapeutics (medscape.com), authors Michael Eller and Peter J Goadsby explain why doctors and their patients should use caution before prescribing an MRI scan for migraines. Their review found:
"Studies demonstrate that there is no appreciable difference in the frequency of pathological and incidental findings in common headache populations compared with the general community. Imaging is therefore not routinely required where a primary headache diagnosis can be made."
In other words, when studying the MRIs of patients with migraines and those from the general patient population, there was no real differences between their brain scans. As a result, the authors conclude that most patients with headaches do not need a brain scan.
What they do need, however, is a thorough examination by a doctor specializing in headaches. This will reveal which migraine treatments, if any, will be the most effective.