Atypical postictal transient subcortical T2 hypointensity in a newly diagnosed diabetic patient with seizures

Abstract

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.

Hemichorea Associated With Non-ketotic Hyperglycemia: A Case Report and Literature Review

“…By actively controlling blood glucose and using dopamine receptor antagonists such as haloperidol, most HC-NH patients have a good prognosis (25), which is also confirmed in the current study. It is important to note that because some patients may develop side effects such as tremors from taking dopamine receptor antagonists, we should start with a small dose and slowly increase the dose and adopt an individualized treatment scheme.…”

Magnetic resonance imaging findings in patients with non-ketotic hyperglycaemia and focal seizures

“…6,[8][9][10][11][12][13][14] These seizures respond well to glycaemic correction and tend to be refractory if treated only with anticonvulsants. 15 The hyperglycaemic non-ketotic state has a proconvulsant effect by lowering the epileptic threshold due to increased GABA metabolism. In fact, during the hyperglycaemic state, the activity of the Krebs cycle and glucose utilisation are reduced in the brain, so the cerebral metabolism shifts to alternative pathways.…”

“…On the other hand, focal subcortical hypointensity on T2-weighted/FLAIR images has been reported as an uncommon MRI finding related to seizures, but it is broadly reported in cases of NKH-related seizures present in the literature, even as an isolated imaging finding without cortical involvement. [6][7][8][9][10][11][12][13][14][15][16][17][21][22][23][24][25][26] These findings are usually unilateral and focal, involving mainly parieto-occipital and perirolandic regions, and show a good correlation with the EEG focus. Previous case reports and small series reporting the presence of MRI abnormalities in a total of 51 patients with NKH-related seizures are listed in Table 2.…”

“…6,8–14 These seizures respond well to glycaemic correction and tend to be refractory if treated only with anticonvulsants. 15…”

Occipital Seizures and Persistent Homonymous Hemianopia (HH) With MRI Subcortical T2 Hypointensity in a Newly Diagnosed Diabetic Patient

“…While motor seizures were widespread, only a few cases of occipital seizures with or without hemianopia were reported [3]. T2-weighted and fluid-attenuated inversion recovery (FLAIR) subcortical hypointensity have been observed in association with NKH, and these findings are occasionally reversible [4]. The major treatment includes managing of hyperglycemia and ensuring enough hydration.…”