Frequency and patterns of MRI abnormalities due to status epilepticus.

Background: MRI changes due to status epilepticus (SE) often suggest a combination of cytotoxic and vasogenic edema, but it is unclear why only certain patients have MRI changes.

Objectives: To determine the frequency of MRI changes due to SE and the associated patient characteristics.

Methods: We reviewed records for demographics, medical history, and MRI changes attributable to seizures of all patients admitted to Brigham and Women's Hospital or Massachusetts General Hospital for SE from 1/1999 to 7/2003 and who had MRI during admission.

Results: Ten (11.6%) of the eighty-six patients identified had MRI abnormalities likely due to seizures. Four, two with pre-existing epilepsy and two with extratemporal structural lesions, had focally increased signal on T2 and diffusion-weighted imaging (DWI) in the hippocampus ipsilateral to the seizure focus. One, with elevated levels of clozapine, had increased signal on T2 weighted images and variably restricted diffusion in the splenium. Five had gyral distribution of restricted diffusion and increased signal on T2 weighted images; they had complex medical comorbidities and possible hypoperfusion or hypoxia associated with SE.

Conclusions: Among patients with SE who had MRI changes, those with previous epilepsy or extratemporal structural lesions showed increased diffusion in the hippocampus and may have selective hippocampal vulnerability to seizure-induced hyperexcitability. Patients with hyperintense signal in the cortical gray matter had episodes of possible hypoperfusion or hypoxia.