MRI scans of migraine sufferers are almost always normal. Occasionally we see white spots on the MRI, which can be also found in people with high blood pressure, dementia, and sometimes in perfectly healthy people (see my previous post on this).
However, Mayo Clinic neurologists, led by Dr. Todd Schwedt reported being able to diagnose chronic migraines on the MRI scan. The accuracy of the diagnosis of those who had 15 or more headache days each month was fairly high – 84%. Patients with this frequency of attacks are considered to be suffering from chronic migraines. However, they could diagnose only 67% of those with episodic migraines (less than 15 headache days each month). The researchers used sophisticated software (FreeSurfer) that measured the surface area, thickness, and volume of 68 various brain regions and discovered that changes in 6 of these regions were predictive of migraine diagnosis. These 6 regions participate in pain processing in the brain and include the temporal lobe, superior temporal lobe, anterior cingulate cortex, entorhinal cortex, medial orbital frontal gyrus, and the pars triangularis. The software used in the study is freely available, but using it is time consuming and it is utilized only by researchers and not by any hospital or private MRI facilities.
Their findings confirmed what until now was an arbitrary decision by headache experts to divide migraines into episodic and chronic ones with a 15 day cutoff. Ahother study by Dr. Richard Lipton and his colleagues at the Montefiore headache clinic has found that those who have 10 or more headache days each month have many similar features compared to those who have less than 10.
This is not a purely academic question. Insurance companies will pay for Botox only if a patient has 15 or more headache days each month because this type of patients was used in clinical trials of Botox. However in practice we also see very good response to Botox in patients who have fewer than 15 days.
