MRI Abnormalities Induced by Seizures

Abstract

When computed tomography started to be used routinely in the evaluation of patients presenting with seizures it became evident that some periictal abnormalities disappeared in follow-up studies with no specific treatment except antiepileptics. These findings suggested that those reversible abnormalities were not structural but functional, possibly resulting from the cerebral edema induced by seizure activity (Goulatia et al. 1987; Sammaritano et al., 1985; Sethi et al., 1985). With the advent of MRI and it’s increasingly use in the acute phase of seizures, these seizureinduced abnormalities were also demonstrated, being described as periictal or reversible MRI abnormalities (Cole 2004; Briellmann et al., 2005); since follow-up MRI studies disclosed that irreversible brain damage can occur in the regions previously affected by them, they are now better defined as transient periictal MRI abnormalities (TPMA). In this way, TPMA should only be considered if two conditions are fulfilled: first, the brain MRI signal abnormalities demonstrated periictally must be attributable to seizures and not other causes; and second, that these abnormalities totally or partially reverse on subsequent MRI studies. Besides the detection of TPMA, MRI can provide us with a unique non-invasive diagnostic tool to better understand the physiopathological mechanisms underlying TPMA formation, and to identify and predict the brain damage induced by seizures. In this chapter, we review the neuroimaging features, differential diagnosis, pathophysiology, electroclinical-imagiological spectrum and outcome of TPMA, highlighting the fundamental role of multi-sequence MRI studies in their investigation.