Table 2 Structural and Functional abnormalities in migraine and cluster headache

Decreased Grey Matter in:

frontal lobes, prefrontal cortex, left medial prefrontal (MPFC), brainstem cortex, cerebellum, temporal lobes Right Superior Temporal; bilateral insula; cingulated cortex; orbitofrontal cortex right occipital lobe right posterior parietal cortex [226,227,228,229,230]

Reduced Fractional Anisotropy values:

superior frontal lobe; medial frontal lobe; Right Inferior Frontal [227, 230]

Thickening of the cortical mantle in the Somatosensory cortex [231]

Decrease Grey Matter in:

right thalamus, bilateral posterior, Hypothalamus, right posterior cingulate cortex, left inferior parietal lobe, head of the right caudate nucleus, bilateral middle frontal gyrus, right-middle temporal gyrus, right precentral gyrus, left insula [64, 78, 79]

Increased Grey matter:

right cuneus [78]

Grey matter volume changes:

Temporal lobe, hippocampus, insular cortex, cerebellum [77].

Changes in Fractional Anisotropy:

Brainstem, thalamus, internal capsule, superior and inferior temporal region, frontal lobe, occipital lobe and cerebellum [101]

Cortical thinning was found in the contralateral angular and precentral gyrus contralateral to the headache side [232]

Enhanced activation in:

perigenual part of anterior cingulate cortex [233] red nucleus, substantia nigra [234], dorsolateral pons [24, 235], cerebellum, insula, cingulate, prefrontal cortices, anterior temporal pole, hippocampus [32]

Decreased activation in: somatosensory cortex [233]

Enhanced activation in:

Posterior hypothalamus, anterior and posterior cingulate cortex, thalamus, basal ganglia, cerebellar hemispheres, prefrontal, insular and temporal cortices [64, 74, 95]

Stronger functional connectivity:

• periaqueductal grey to the ventrolateral prefrontal cortex, supramarginal gyrus, anterior insula, precentral gyrus, postcentral gyrus, and thalamus [33]

• anterior cingulate cortex to middle temporal, orbitofrontal cortex, and dorsolateral prefrontal cortex [229]

• caudate nucleus to the parahippocampal gyrus, amygdala, insular cortex, and putamen; nucleus accumbens to the parahippocampal, anterior cingulate cortex, orbitofrontal cortex [236]

• Medial prefrontal cortex to the posterior cingulate cortex (coppola 2017)

• Medial prefrontal cortex and left to the right inferior parietal lobules and bilateral insula [237]

Atypical Functional connectivity of:

• salience network, default mode network, central-executive network, somatomotor network, and frontoparietal attention network [34]

• left rostral anterior cingulated cortex, bilateral prefrontal cortex and right thalamus [97]

Stronger functional connectivity of:

• hypothalamus to parts of the frontal, parietal and temporal cortex during headache free intervals; to the Anterior Cingulate Cortex and Posterior Cingulate Cortex during the acute spontaneous CH [87]

• attention network ipsilateral to a headache paine and in the contralateral cerebellar network [75]

Atypical Functional connectivity of:

• the hypothalamus both ipsilateral and contralateral to the CH side and the salience network [238]

Decreased functional connectivity of:

• the hypothalamus with the medial frontal gyrus, precuneus and cerebellar areas [97]