Besides a general correlation between the two diseases, the migraine attack itself temporarily correlates with RLS episodes. In a study done at China Medical University in Taiwan, Dr. Chen and his colleagues studied patient diaries that record both migraine headaches episodes and RLS episodes. They found that a patient is more likely to experience a RLS episode within 2 days of a migraine attack. In addition, there is a correlation between the severity of the migraine and the RLS – the worse the migraine, the worse the RLS episode that develops. This correlation, however, does not support the opposite as migraine attacks tend to follow RLS attacks only within one day.
The reason why the two diseases are correlated is unknown in part due to our lack of knowledge of the exact neurological mechanism for RLS. And, to some extent, what triggers a migraine attack. There are, however, various educated speculations. One theory is that sleep quality confers a common link between the two diseases. Patients with RLS tend to have poor sleep qualities( from both the symptom of leg discomfort as well as the syndrome itself) and as many migraineurs would agree, a poor night’ s sleep can often trigger a migraine attack. As Dr. Oosterhout from Leiden University Medical center stated:“ Restless leg syndrome is associated with lower sleep quality and fragmented sleep, which are known triggers for migraine attacks.”
Of course, he does not preclude the possibility of another hypothesis – that a neurochemical called dopamine is the cause of both conditions. Dopamine is a chemical in the brain that modulates rewards and risk-taking behaviors. It is also implicated in both RLS and migraine. Dopamineblocking medications, for example, have been shown to help with migraine. Medications that act like dopamine in the brain( dopamine agonists), on the other hand, tend to
help with RLS. Dr. Chen, who reported on the migraine diary study, postulates that as dopamine tends to be lower at night but higher during the day, this diurnal imbalance may precipitate the characteristic night time attacks of RLS. Incidentally, levels of serotonin, a sister neurochemical molecule that works against dopamine and prevents dopamine’ s release, are high after a migraine attack. This transient opposition after a migraine, Dr. Chen argues, maybe what provokes RLS after a migraine.
However, dopamine is not the only link between migraine and RLS. Researchers have also speculated that iron homeostasis( balance) might be a culprit. Iron is an important factor in dopamine and iron deficiency is one of the most common causes of RLS. Incidentally, while iron levels are normal in migraineurs, MRI studies offer some evidence that abnormal iron deposs in the brain may be involved in migraine attacks. It is possible that the iron imbalance between how the body allocates iron in the brain versus the rest of the body may play a part in both migraine and RLS. The iron hypothesis has support in genetic research. In a paper published in 2015, Dr. Fuh from Taiwan’ s National Yang-Ming University School of Medicine suggests that a gene called MEIS1 is associated with increased risk of RLS in migraine patients. This gene plays a part in the iron transportation pathway in the body. Dr. Fuh’ s team speculated that variations of MEIS1 gene affects iron transportation which in turn affects dopamine, causing RLS and migraine.
Regardless of the cause of restless leg syndrome and migraine, RLS is an important syndrome to recognize in migraine. As Dr. Chen suggests, if there really is a bidirectional link between RLS and migraine severity( and frequency), then improvement in one syndrome may benefit the other. HW
22 HeadWise ® | Volume 6, Issue 3 • 2017
170767 _ LOT A _ NHF Feb 2017 Vol. 6 Issue 3. indd 22 2 / 15 / 17 12:48 AM