MTLE with hippocampal sclerosis in adult as a syndrome

Mesial temporal lobe epilepsy with hippocampal sclerosis, (MTLE-HS) is a well characterized disorder which associates electroclinical features suggestive of seizure onset in the mesial or limbic structures of the temporal lobe, and hippocampal sclerosis. This underlying pathology differentiates MTLE-HS from MTLE due to other pathological substrates. Typically, when MTLE-HS is diagnosed, a typical course of the disease can be retrospectively recognized, including early prolonged febrile seizures, a latent period, onset in mid-to-late childhood, auras that may initially occur in isolation, periods of seizure remission during adolescence or early adulthood. Then the condition progresses, associating elaborated seizures, progressive drug-resistance and cognitive, mainly memory, disorders of variable intensity. The seizures have a relatively gradual onset/offset, developing over 1-2minutes, with partial awareness at the onset, and lasting for 2 to 10minutes. Auras are common, with visceral, autonomic, psycho-affective, experiential components, presenting less frequently diverse sensory or sensorial symptoms. Awareness is generally preserved at onset, but then loss of consciousness occurs, with initial motionless stare, and automatisms, which typically are oro-alimentary, vocal or gestural, accompanied by motor signs such as contralateral dystonic posturing. A dysphasia is frequent when the focus is in the dominant hemisphere, often prolonged by a post-ictal dysphasia and confusion. Interictal EEG shows anterior or mid-temporal spikes/sharp ipsilaterally to the focus, in combination with non-epileptiform regional slowing. These changes may be bilateral but usually predominates ipsilaterally. Ictal EEG changes are marked by rhythmic temporal alpha or theta activity within 30seconds of clinical onset. The hallmark is the presence of hippocampal sclerosis, demonstrable on coronal MRI sequences by unilateral (or asymmetrical) decrease in hippocampal volume and increase in signal on T2-weighted sequences. The diagnosis of MTLE is crucial because of its frequent poor prognosis under antiepileptic drugs, and of the possibility of excellent results after resective surgery. PET scanning shows a typical antero-mesial hypometabolism extending to the pole and lateral aspects of the temporal lobe. Presurgical investigations may also include depth-electrode recordings in case of doubt about more extensive or bilateral onsets. They demonstrate and lateralize the amygdalo-hippocampal discharges, some of them remaining apparently asymptomatic in the absence of extrahippocampal spreading. These interactions between hippocampal and extrahippocampal networks confer its specificity to MTLE-HS, together with its remarkable natural course. This entity is diagnostically essential, whether it should be regarded as an epileptic syndrome, disease or a distinctive constellation.