Study Explores The Chiari-Migraine Connection...

Headaches are the most common symptom associated with Chiari. Whether its throbbing in the back of the head (suboccipital), pressure behind the eyes, or brought on by coughing, crying, or singing, the majority - but not all - of Chiari patients suffer from some type of headache. One such headache which seems to be common among Chiari patients are migraines.

Migraines refer to severe headaches, which usually recur, and can include changes in vision (known as an aura). Unfortunately, when a person with migraines and Chiari seeks help from a doctor, the migraines can become the focus of treatment since they are more common. This can mask the underlying Chiari problem and delay an accurate diagnosis and treatment.

Although most Chiari experts would agree that there appears to be some type of connection between Chiari and migraines, the nature of that link is a complete unknown. Now, researchers from Turkey have published a study in the journal, Clinical Neurology and Neurosurgery which clearly demonstrates a link, but comes short of clarifying its precise nature.

The researchers identified 73 Chiari patient they had treated over a two year period. Chiari was defined as a malformation of at least 5 mm on MRI, or at least 3 mm with additional indicators, such as peg shaped tonsils or kinking. Each patient was interviewed by the same neurologist to establish a detailed history of headaches. In addition, information was collected on patient demographics, the frequency, duration, and intensity of headaches, family history of headaches, activities that made the headaches worse, and use of mediations to treat the headaches. Only adults were included in the study.

Of the 73 people with Chiari, 11 (15%) were found to suffer from migraines
Figure 1: Frequency of Migraines Among Chiari Patients (73 Total)
Number Percent
Migraine 11 15%
Chronic Migraine 8 11%
Migraine w/aura 2 3%
which is not significantly different from the general population. However of those with migraines, 8 of the 11 suffered from chronic migraines (more than 15 days a month), which is three times the rate in the general population. Finally, two were found to suffer migraines with auras, which are visual disturbances such as flashing lights.

Next, the researchers chose to compare the Chiari-migraine sufferers to people with migraines but no Chiari. To do this, they created a control group of migraine patients with normal MRIs, who were selected to match the general age and gender make up of the Chiari group.

In comparing the two groups, the scientists found a number of notable differences Figure 2: Significant Differences Between Chiari Migraine Patients and General Migraine Patients
Chiari Migraine General Migraine
Age at onset 12.75 24.7
# days per month 23 17
Pain intensity 7 5.2
Number w/nausea 8 4
Number w/vomiting 8 2
Aggravated by physical activity 8 3

Specifically, the Chiari group tended to begin having migraines at a much younger age (13 years) than the general migraine group (25 years). In addition, the Chiari group on average suffered from migraines 6 days more a month than the control group. The intensity of headaches was also higher in the Chiari group, averaging 7 on a scale of 0-10 versus 5 for the migraine only group. Finally, the number of people who suffered from nausea and vomiting was higher in the Chiari group. Although, there were only 10 patients in the Chiari group and 8 in the control group, all these differences were found to be statistically significant, meaning the difference is not likely to be due to chance.

However, given the small size of the study, the results should be considered preliminary and used as a guide for further research, rather than a basis for strong conclusions. For example, beyond simply repeating this study with more patients, it would be interesting to compare Chiari patients who have migraines to Chiari patients who don't. Are there anatomical differences, such as the size of their posterior fossas? Or perhaps a difference woul be found in the cerebrospinal fluid which would provide a clue as to the nature of the connection between Chiari and migraines.

While Chiari is fundamentally a structural problem, no known structural abnormalities - such as could be seen on an MRI - have been found in association with migraines. Based on this research it is difficult to speculate on why chronic migraines would be more frequent among Chiari patients, but the authors do point out that one migraine theory involves pain centers found in the brainstem. The herniated tonsils with Chiari can easily put pressure on the brainstem and other brainstem issues, such as central sleep apnea, have been found to be more frequent among Chiari patients.

Although not fully understood, it seems clear that there is some type of connection between migraines and Chiari. An interesting question to answer with future research is whether decompression surgery reduces the frequency and/or intensity of migraines among Chiari patients.

-- Rick Labuda