Abnormal, time-varying brain connectivity between the thalamocortical and frontoparietal pathways can contribute to migraine symptoms. These results from an analysis of functional magnetic resonance imaging (fMRI) data have been published in the Journal of Headache and Pain.
Study researchers recruited patients with episodic or chronic migraines (n = 20) and participants in a healthy control group (n = 26) through local advertising. All participants underwent an fMRI assessment at the University of Michigan asking them to relax, put visual focus on a screen, and think of nothing. The blood oxygen level-dependent signal variability (BOLDSV) was calculated using low frequencies (0.01-0.198 Hz).
Patients and participants in the control group were well balanced for age (P = 0.428) and gender (P = 0.818). In patients with chronic or episodic migraines, there was no difference in terms of duration of illness (P = 0.945), threshold of ictal thermal pain (P = 0.202), intensity of ictal pain (P = 0.246) or the 6-point Headache Impact Test (P = 0.086).
Specific regional differences in the BOLDSV patterns were observed between participants in the control group and patients with migraines, and between patients with chronic migraines and patients with episodic migraines. The study researchers averaged these observations and cross-correlation plots showed that the BOLD signal fluctuations were in a time-synchronized pattern between the trigeminal spinal-thalamo-cortical and frontoparietal pathways.
Using direct conditional correlation analysis, the patterns of strength (P <0.05) and variability (P <0.05) between the ventral posteromedial nucleus and the primary somatosensory cortex with dynamic functional connectivity (dFC) differed between control and participants Patient. Patients with chronic migraines had significantly higher dFC strength and lower variability compared to control group participants (all P <0.05). Patients with episodic migraines had a higher variability in dFC (P <0.05).
All patients had a lower level of dFC between the lower parietal cortex and the right dorsolateral prefrontal cortex compared to participants in the control group (P <0.01), which was more likely to affect patients with episodic (P <0.01) than chronic ( P <0.05) was due to migraines.
The severity of the headache correlated with an increased BOLDSV in the left medial pulvinary core (r, 0.697; P = 0.006), in the primary somatosensory cortex (r, 0.662; P = 0.010), and in the right spinal trigeminal core (r, 0.595; P =). 025) and dorsal posterior insula (r, 0.558; P = 0.038).
This study was limited due to the small sample size of patients with chronic and episodic migraines and the fact that general findings in all patients may only be determined by a subset of individuals.
The study researchers concluded, “Migraine is associated with changes in signal variability over time in the ascending somatosensory trigeminal and top-down modulation pathways, which may explain migraine-related pain and allodynia. Contrasting patterns of time-varying connectivity within the thalamocortical and frontoparietal pathways could be associated with abnormal network integrity and instability for pain transmission and modulation. ”
Disclosure: One author stated links to the pharmaceutical industry. For a full list of details, see the original article.
Lim M, Jassar H., Kim DJ, Nascimento TD, DaSilva AF. Differential change in the variability of the fMRI signal in the ascending somatosensory and pain-modulating trigeminal pathways in migraine. J headache. 2021; 22 (1): 4. doi: 10.1186 / s10194-020-01210-6.