Dumkrieger, Gina M

AbstractPosttraumatic headache (PTH) is the most common symptom following mild traumatic brain injury (mTBI) (also known as concussion). Migraine and PTH have similar phenotypes, and a migraine-like phenotype is common in PTH. The similarities between both headache types are intriguing and challenge a better understanding of the pathophysiological commonalities involved in migraine and PTH due to mTBI. Here, we review the PTH resting-state functional connectivity literature and compare it to migraine to assess overlap and differences in brain network function between both headache types. Migraine and PTH due to mTBI have overlapping and disease-specific widespread alterations of static and dynamic functional networks involved in pain processing as well as dysfunctional network connections between frontal regions and areas of pain modulation and pain inhibition. Although the PTH functional network literature is still limited, there is some evidence that dysregulation of the top-down pain control system underlies both migraine and PTH. However, disease-specific differences in the functional circuitry are observed as well, which may reflect unique differences in brain architecture and pathophysiology underlying both headache disorders.

Objective To interrogate hippocampal morphology and structural co‐variance patterns in migraine patients and to investigate whether structural co‐variance patterns relate to migraine disease characteristics. Background Migraine is associated with structural alterations in widespread cortical and subcortical regions associated with the sensory, cognitive, and affective components of pain processing. Recent studies have shown that migraine patients have differences in hippocampal structure and function relative to healthy control subjects, but whether hippocampal structure relates to disease characteristics including frequency of attacks, years lived with migraine and symptoms of allodynia remains unknown. Furthermore, this study investigated hippocampal volume co‐variance patterns in migraineurs, an indirect measure of brain network connectivity. Here, we explore differences in hippocampal volume and structural co‐variance patterns in migraine patients relative to healthy controls and examine whether these hippocampal measures relate to migraine disease burden. Methods This study included 61 migraine patients and 57 healthy control subjects (healthy controls: median age = 34.0, IQR = 19.0; migraine patients: median age = 35.0, IQR = 17.5; P = .65). Regional brain volumes were automatically calculated using FreeSurfer version 5.3. Symptoms of allodynia were determined using the Allodynia Symptom Checklist 12 (ASC‐12). Structural co‐variance patterns were interrogated using pairwise correlations and group differences in correlation strength were estimated using Euclidian distance. A stepwise regression was used to investigate the relationship between structural co‐variance patterns with migraine burden. Results Migraine patients had less left hippocampal volume (healthy controls: left hippocampal volume = 4276.8 mm 3 , SD = 425.3 mm 3 , migraine patients: left hippocampal volume = 4089.5 mm 3 , SD = 453.9 mm 3 , P = .02) and less total (right plus left) hippocampal volume (healthy controls: total hippocampal volume= 8690.8 mm 3 , SD = 855.1 mm 3 ; migraine patients: total hippocampal volume = 8341.8 mm 3 , SD = 917.9 mm 3 ; P = .03) compared to healthy controls. Migraineurs had stronger structural covariance between the hippocampi and cortico‐limbic regions in the frontal lobe (inferior opercular gyrus), temporal lobe (planum temporale, amygdala), parietal lobe (angular gyrus, precuneus), and the cerebellar white matter. Results of a stepwise regression showed that hippocampal volumes and the interactions between hippocampal volumes with the volumes of other cortico‐limbic regions associate with migraine‐related allodynia but not with headache frequency or years lived with migraine. Conclusion Migraineurs have less hippocampal volume and stronger hippocampal‐cortico‐limbic connectivity compared to healthy controls. Hippocampal volumes and measures of hippocampal volume connectivity with other cortico‐limbic network regions associate with symptoms of allodynia.