Transient MR Signal Changes in Patients with Generalized Tonicoclonic Seizure or Status Epilepticus: Periictal Diffusion-weighted Imaging

Images of a 12-year-old male patient (patient 2) with generalized tonicoclonic seizure.

A, Initial FLAIR image shows increased signal intensity in the cortical gray matter and subcortical white matter in cuneus and precuneus bilaterally (arrows).

B, Initial diffusion-weighted image shows mildly increased signal intensity in the corresponding areas (arrows). The decrease of the mean ADC was 8% at the right and 6% at the left on the ADC map (not shown).

C, Follow-up T2-weighted image obtained 14 days after the onset of seizure shows complete resolution of the signal change.

Images of a 2-year-old female patient (patient 6) with complex partial status epilepticus with secondary generalization.

A, Initial T2-weighted image shows increased signal intensity and swelling in the right hippocampus (arrow).

B, Initial diffusion-weighted image shows increased signal intensity in the right hippocampus (arrow).

C, Corresponding ADC map shows 14% decrease of mean ADC (arrow).

D, Follow-up FLAIR image obtained 18 months after the onset of seizure shows the resolution of the swelling and mass effect of the hippocampus (arrow) and increased T2 signal intensity without definite atrophic change of the hippocampus.

Images of a 60-year-old woman (patient 7) with simple partial status epilepticus sustained for 5 days.

A, Ictal T2-weighted images show extensive swelling and increased signal intensity of the left hippocampus (left) and diffuse swelling with increased signal intensity at the cortical gray matter and subcortical white matter of the adjacent left temporal lobe (right).

B, Ictal diffusion-weighted images show increased signal intensity and swelling at the left hippocampus (left, arrows) and at the uncus (right, arrowhead), parahippocampal gyrus (right, black arrow), and inferior temporal gyrus (right, white arrow).

C, ADC maps show a 19% decrease of the mean ADC at the left hippocampus (left, arrow) and a 2% to 5% increase of the mean ADC at the subcortical white matter of the uncus, parahippocampal gyrus, and inferior temporal gyrus (right).

D, Follow-up T2-weighted images obtained 4 months after the onset of seizure show the resolution of the marked swelling of the left hippocampus and partial resolution of the increased signal intensity of the left hippocampus (left). A tumor was revealed, which was diagnosed as glioblastoma multiforme at the left anterior temporal lobe (right).

Continued.

E, Light microscopic image of the left hippocampus obtained by amygdalohippocampectomy reveals extensive neuronal loss and gliosis in the CA4 area of the hippocampus (left: arrowheads, granule cell layer of dentate gyrus; arrow, remaining neuron in CA4) and neuronal loss and gliosis in the CA2 area of the hippocampus (right). More neurons are preserved in the CA2 area than in the other areas of the hippocampus (CA4, CA3, and CA1).

Images of a 51-year-old woman (patient 8) with generalized tonicoclonic status epilepticus.

A, Initial FLAIR images show multiple increased signal intensity and swelling at the cortical gray matter and subcortical white matter of the right inferior frontal gyrus (left, arrowhead), right insular cortex (left, short arrow), left superior, middle, and inferior temporal gyri (right, open arrows), and bilateral hippocampi (long arrows).

B, Initial diffusion-weighted images show increased signal intensity at the right inferior frontal gyrus (left, arrows), left temporal lobe (middle), and bilateral hippocampi (right, arrows).

C, Follow-up diffusion-weighted images show resolution of the signal changes of the right frontal (left) and left temporal (middle) lobe. The increased signal intensity at the bilateral hippocampi did not resolve (right).