Abstracts

Magnetic resonance imaging (MRI) changes due to status epilepticus (SE) have been documented in both animal models and humans. The etiology of MRI changes due to seizures is unknown, although MRI effects are often suggestive of a combination of cytotoxic and vasogenic edema. It is not yet apparent why only certain patients have MRI changes and whether the etiology of the seizure influences the MRI manifestations. Using a research patient database, the records of all patients who were admitted to Brigham and Women[apos]s Hospital or Massachusetts General Hospital for SE from 1/1999-7/2003 and who also received MRI were reviewed for etiology of SE and MRI changes attributed to seizures. Eighty-six patients were identified. Ten patients had MRI abnormalities that were likely due to seizures. These consisted of focally increased T2 signal with reversible restricted diffusion in the hippocampus corresponding to the seizure focus (5 cases), increased T2 signal and variable restricted diffusion in the splenium (1 case), and a larger gyral pattern of restricted diffusion corresponding to the apparent seizure focus (4 cases).
In the 5 cases of reversible restricted diffusion in the hippocampus ipsilateral to the side of seizure onset, 3 had epilepsy (2 with extratemporal vascular malformations, 1 with hippocampal sclerosis), and in the other two SE was their initial seizure presentation (1 each with malignant glioma and multiple sclerosis). The patient with focal edema of the splenium had elevated levels of clozapine, and MRI became normal after discontinuation of clozapine and initiation of anticonvulsants. All 4 patients with a gyral pattern of restricted diffusion had possible hypoperfusion and/or hypoxia associated with their seizures; 2 patients had acute myocardial infarctions requiring intubation, 1 had multiple metabolic derangements with episodic hypotension, and 1 had ipsilateral subclavian steal syndrome. Two of these 4 patients died, 1 clinically resolved but did not receive follow-up imaging, and one showed resolution of T2 hyperintensity but developed diffuse atrophy. In this series of 86 patients in SE, the incidence of MRI changes attributed to seizures was 11.6%. A gyriform pattern of restricted diffusion in the cortical gray matter was seen in patients with possible hypoperfusion in the region of seizure origin. When this pattern is seen in patients with SE, ischemic and/or hypoxic injury should be suspected. The pattern of reversible restricted diffusion in the hippocampus was seen in patients with either hippocampal sclerosis or extratemporal structural lesions, and may demonstrate selective vulnerability of the hippocampus in these situations to seizure induced edematous changes. (Supported by Brigham and Women[apos]s Hospital Translational Neuroscience Grant)