Aetiologies of Subcortical T2 Hypointensity on MRI in Patients Presenting with Seizures or Visual Symptoms: A Cross-sectional Study

Introduction: Magnetic Resonance Imaging (MRI) findings in seizures associated with hyperglycaemia, particularly non ketotic hyperglycaemia, are distinctive and can aid diagnosis. Characteristic features include focal subcortical T2-weighted hypointensity, with or without cortical hyperintensity, reflecting underlying metabolic disturbances. Aim: To analyse patients presenting with seizures or visual symptoms who demonstrate subcortical T2 hypointensity on MRI and by correlating these radiological patterns with clinical and laboratory findings. Materials and Methods: This cross-sectional study was conducted in the Department of Radiodiagnosis, Mahatma Gandhi Medical College and Hospital, Jaipur, Rajasthan, India, between 2020 and February June 2022. Patients presenting with seizures and/or visual disturbances who demonstrated focal subcortical T2 hypointensity on MRI were included. Imaging was performed on 1.5T and 3T scanners. Sequences analysed included T2, Fluid Attenuated Inversion Recovery (FLAIR), Diffusion Weighted Imaging (DWI), Apparent Diffusion Coefficient (ADC), and Susceptibility Weighted Imaging/Gradient Echo (SWI/GRE). Results: Twenty-two patients were evaluated. Hyperglycaemia was confirmed in nine patients (serum glucose 384-520 mg/dL; HbA1c 7.1-14%). MRI consistently showed subcortical hypointensity on T2-weighted, FLAIR, and SWI/GRE sequences, with corresponding reduced signal on DWI. No haemorrhage was detected. The parieto-occipital lobes were predominantly affected (77.8%), while frontal and temporal lobes were less frequently involved (22.2%). One patient demonstrated complete resolution of abnormalities on follow-up after glycaemic control. The remaining 13 patients had alternative diagnoses, including infarcts, meningitis, metastases, cerebritis, and Sturge-Weber syndrome. Conclusion: Subcortical T2 hypointensity, especially in the parieto-occipital regions, is a subtle but reliable MRI marker of hyperglycaemia-related seizures. Recognition of this finding facilitates accurate diagnosis, prevents misinterpretation as stroke or infection, and enables timely initiation of metabolic correction. Isolated subcortical T2 hypointensity in the parietooccipital regions should alert radiologists to hyperglycaemia as an underlying cause of seizures or visual symptoms, allowing timely metabolic correction and complete reversibility of MRI findings.