In this study we used nitroglycerin (NTG)-induced migraine attacks as a translational human disease model. Static and dynamic functional connectivity (FC) analyses were applied to study the associated functional brain changes. A spontaneous migraine-like attack was induced in five episodic migraine (EM) patients using a NTG challenge. Four task-free functional magnetic resonance imaging (fMRI) scans were acquired over the study: baseline, prodromal, full-blown, and recovery. Seed-based correlation analysis (SCA) was applied to fMRI data to assess static FC changes between the thalamus and the rest of the brain. Wavelet coherence analysis (WCA) was applied to test time-varying phase-coherence changes between the thalamus and salience networks (SNs). SCA results showed significantly FC changes between the right thalamus and areas involved in the pain circuits (insula, pons, cerebellum) during the prodromal phase, reaching its maximal alteration during the full-blown phase. WCA showed instead a loss of synchronisation between thalami and SN, mainly occurring during the prodrome and full-blown phases. These findings further support the idea that a temporal change in thalamic function occurs over the experimentally induced phases of NTG-induced headache in migraine patients. Correlation of FC changes with true clinical phases in spontaneous migraine would validate the utility of this model.

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Common postictal MRI findings include transient cortical T2 hyperintensity, restricted diffusion, and gyral and/or adjacent leptomeningeal contrast enhancement. In certain uncommon pathological conditions, other signal abnormalities can be present, suggesting a different underlying pathogenic mechanism. We report the case of a 66‐year‐old man, recently diagnosed with diabetes mellitus type 2, presenting with new‐onset visual and auditory hallucinations, “absence” seizures, and repeated peaks of hyperglycaemia without hyperketonaemia or increased serum osmolarity. EEG confirmed epileptic discharges in the right temporal region and MRI showed vast subcortical T2 hypointensity in the right temporal lobe, without any cortical hyperintensity, restricted diffusion, or contrast enhancement. Subcortical signal abnormality and EEG discharges resolved after a month of follow‐up, with a small juxtacortical gliotic focus as a sequela. Peaks in hyperglycaemia have been reported to be responsible for T2 hypointense subcortical abnormalities through a proconvulsant mechanism linked to increased ketone body concentrations. Hyperosmolarity and hyperketonaemia were not evident in this case, however, transient accumulation of free radicals that alter the intercellular space can be considered the presumable cause of this finding. In summary, it is important to consider any unusual findings on postictal MRI in order to avoid errors in interpretation.

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