Abnormally Increased Effective Connectivity of the Periaqueductal Gray in Migraine Without Aura Patients

Objectives: The periaqueductal gray (PAG) is a key region in the descending pain modulatory system. We applied a Granger causality analysis-based approach to examine resting-state effective connectivity of the bilateral PAG regions in migraine patients without aura (MwoA).

Materials and methods: Resting-state functional magnetic resonance imaging data were obtained from 28 MwoA patients and 17 healthy controls. The effective connectivity of the bilateral PAG was characterized using a voxel-wised Granger causality analysis method. The resulting effective connectivity measurements were assessed for correlations with other clinical features.

Results: Compared with the healthy controls, MwoA patients showed increased effective connectivity from the left PAG to the left anterior cingulate gyrus and right postcentral gyrus. Meanwhile, MwoA patients also showed increased effective connectivity from the right PAG to the left precentral gyrus and increased effective connectivity from the left caudate and right middle occipital gyrus to the right PAG.

Discussion: Abnormally increased effective connectivity between PAG and limbic system, primary sensorimotor cortex, and visual cortex may play a key role in neuropathological features, perception, and affection of MwoA. The current study provides further insights into the complex scenario of MwoA mechanisms.