Previous studies have shown that patients with migraine have abnormal processing of feeling inputs, including painful stimuli, during and between migraine attacks. During a migraine attack, the majority of migraineurs are overly sensitive to light, sound, smell and some touch stimuli.
Between migraine attacks, some sufferers also have persistent sensitivity. In terms of pain, previous studies have shown that pain exposure may increase the thickness of cortex and that this can normalise after the pain resolves.
So now, researchers have measured the thickness of the processing part of the brain (the cortex) in areas of the brain that are used to process pain, and compared it to how severely they felt a painful stimulus (in this case heat). They did so in 31 adults with migraine and 32 control subjects, who were well.
The study authors found that in normal subjects, like numerous studies before them, “those subjects with lower pain thresholds (i.e. those in whom less intense heat was required to cause pain) had thicker cortex” in the appropriate brain regions. However, in migraine patients, the opposite seems to be true: “migraine subjects with lower pain thresholds (i.e. were more sensitive to heat pain) had thinner cortex in these regions”.
In other words, migraine sufferers did not have a normal ratio of pain threshold to thickness of cortex, most prominently in an parts of the brain called the superior temporal and inferior parietal lobes. These areas of the brain have been associated with a person’s ability to pay attention to stimuli from the environment.
The hypothesis from the study is that migraine sufferers are less able to direct attention away from pain and therefore their experience of pain is more significant.