This report describes a patient who had a first generalized tonic clonic se
izure (GTCS) at the age of 18 years. The initial MRI scan was normal on vis
ual and quantitative examination. After a further six GTCS, a second MRI sc
an showed reduced hippocampal volume and increased hippocampal T2 signal, w
hich was confirmed in a third scan. Therefore, hippocampal sclerosis may be
acquired in adulthood after brief GTCS.