Migraine Is Associated With High Sodium Levels in CSF
Migraineurs have significantly higher sodium concentrations in their CSF than people without migraine, according to the first study to use a technique called sodium MRI to examine patients with migraine.
Diagnosis of migraine is challenging, as the characteristics of migraines and the types of attacks vary widely among patients. Consequently, many patients with migraine are undiagnosed and untreated. Other patients, in contrast, are treated with medications for migraines even though they have a different type of headache, such as tension-type headache.
“It would be helpful to have a diagnostic tool supporting or even diagnosing migraine and differentiating migraine from all other types of headache,” said Melissa Meyer, MD, a radiology resident at the Institute of Clinical Radiology and Nuclear Medicine at University Hospital Mannheim and Heidelberg University in Heidelberg, Germany.
Dr. Meyer and colleagues explored a technique called cerebral sodium MRI as a possible means to help in the diagnosis and understanding of migraine. While MRI most often relies on protons to generate an image, sodium can be visualized as well. Research has shown that sodium plays an important role in brain chemistry.
The researchers recruited 12 women (mean age, 34) who had been clinically evaluated for migraine. The women filled out a questionnaire regarding the length, intensity, and frequency of their migraine attacks and accompanying auras. The researchers also enrolled 12 healthy women of similar age as a control group. Both groups underwent cerebral sodium MRI. Sodium concentrations of patients with migraine and healthy controls were compared and statistically analyzed.
The researchers found no significant differences between the two groups in sodium concentrations in the gray and white matter, brainstem, and cerebellum. Significant differences emerged, however, when the researchers looked at sodium concentrations in the CSF. Overall, sodium concentrations were significantly higher in the CSF of migraineurs than in healthy controls.
“These findings might facilitate the challenging diagnosis of a migraine,” said Dr. Meyer. The researchers hope to learn more about the connection between migraine and sodium in future studies. “As this was an exploratory study, we plan to examine more patients, preferably during or shortly after a migraine attack, for further validation.”
Gadolinium May Not Cause Neurologic Harm
There is no evidence that accumulation of gadolinium in the brain speeds cognitive decline, according to researchers.
“Approximately 400 million doses of gadolinium have been administered since 1988,” said Robert J. McDonald, MD, PhD, a neuroradiologist at the Mayo Clinic in Rochester, Minnesota. “Gadolinium contrast material is used in 40% to 50% of MRI scans performed today.”
Scientists previously believed that gadolinium contrast material could not cross the blood–brain barrier. Recent studies, however, including one by Dr. McDonald and colleagues, found that traces of gadolinium could be retained in the brain for years after MRI.
On September 8, 2017, the FDA recommended adding a warning about gadolinium retention in various organs, including the brain, to labels for gadolinium-based contrast agents used during MRI. The FDA highlighted several specific patient populations at greater risk, including children and pregnant women. Yet little is known about the health effects, if any, of gadolinium that is retained in the brain.
For this study, Dr. McDonald and colleagues set out to identify the neurotoxic potential of intracranial gadolinium deposition following IV administration of gadolinium-based contrast agents during MRI. The researchers used the Mayo Clinic Study of Aging (MCSA), the world’s largest prospective population-based cohort on aging, to study the effects of gadolinium exposure on neurologic and neurocognitive function.
All MCSA participants underwent extensive neurologic evaluation and neuropsychologic testing at baseline and 15-month follow-up intervals. Neurologic and neurocognitive scores were compared using standard methods between MCSA patients with no history of prior gadolinium exposure and those who had undergone prior MRI with gadolinium-based contrast agents. Progression from normal cognitive status to mild cognitive impairment and dementia was assessed using multistate Markov model analysis.
The study included 4,261 cognitively normal men and women between ages 50 and 90 (mean age, 72). Mean length of study participation was 3.7 years. Of the 4,261 participants, 1,092 (25.6%) had received one or more doses of gadolinium-based contrast agents, with at least one participant receiving as many as 28 prior doses. Median time since first gadolinium exposure was 5.6 years.
After adjusting for age, sex, education level, baseline neurocognitive performance, and other factors, gadolinium exposure was not a significant predictor of cognitive decline, dementia, diminished neuropsychologic performance, or diminished motor performance. No dose-related effects were observed among these metrics. Gadolinium exposure was not an independent risk factor in the rate of cognitive decline from normal cognitive status to dementia in this study group.
“There is concern over the safety of gadolinium-based contrast agents, particularly relating to gadolinium retention in the brain and other tissues,” said Dr. McDonald. “This study provides useful data that at the reasonable doses [that] 95% of the population is likely to receive in their lifetime, there is no evidence at this point that gadolinium retention in the brain is associated with adverse clinical outcomes.”