As most patients in whom surgery is considered suffer from TLE for a period of at least several years, it is important to understand how this ongoing disease interferes with brain functioning. If a prolonged disease course has a negative impact on brain functioning in TLE patients, this would support the importance of early surgical intervention. However, relatively little is known about the natural history of TLE. It is often preceded by an initial precipitating injury, of which a complex febrile seizure is the most common [5]. Hereafter, a latent period tends to occur, followed by recurrent, spontaneous seizures, indicating that TLE might be a progressive disease [6]. When looking at structural damage related to epileptic seizures, progressive volume loss of the hippocampus, amygdala and the entorhinal cortex has been described as a consequence of ongoing TLE [4]. A correlation between the number of brain structures with epileptogenic characteristics and epilepsy duration has been described in TLE patients [7]. It is not known how functional neural networks change during disease progression, and what the impact of changes is on seizure initiation and propagation. However, a contralateral increase of functional connectivity for TLE patients has been described [8].
