Prevalence
~20% of patients with epilepsies; 65% of mesial TLE.

Age at onset
Late childhood or adolescence.

Sex
Males = females.

Neurological and mental state
Usually normal prior to seizure onset.

Etiology
Hippocampal sclerosis.

Clinical manifestations
Pre-existing complex febrile convulsions are common. Simple focal seizures are the initial non-febrile seizures followed by complex focal seizures or generalized convulsions.

Main ictal manifestations include ascending epigastric aura and fear in simple focal seizures. Oro-alimentary automatisms typically occur in complex focal seizures (~70%).

Complex internal sensations and illusions occur but not as common as in extra-hippocampal epilepsies. Olfactory and gustatory hallucinations are less often.

Post-ictal symptoms are frequent and often severe.

Secondarily generalized tonic-clonic seizures (GTCS) are infrequent in properly treated patients.

Complex focal status epilepticus occur, particularly in untreated patients. Less common than absence status epilepticus.

Diagnostic procedures
MRI provides in vivo visualization of hippocampal sclerosis in all patients. 'Double pathology' such as malformations of cortical development may co-exist.

Functional brain imaging and other new methodologies offer significant insights and practically eliminate the need for invasive techniques in neurosurgical evaluation.

Inter-ictal EEG
In half of patients, single routine EEG is normal or with non-specific abnormalities. Only 1/3 show the classic spike or sharp and slow-wave focus in the anterior temporal electrode. Prolonged EEG monitoring, along with sleep EEG, increases the yield to 70% to 80%. Half have regional temporal inter-ictal runs of slow waves, which are of lateralizing value.

Ictal EEG
Rhythmic 4 to 7 Hz slow activity over the affected temporal lobe, before or simultaneously with clinical events. Fast spiking is exceptional.

Prognosis
Largely unknown. In neurosurgical series, initially, patients have a rather mild or uneventful course of hippocampal seizures that may be controlled with medication. Later, within years, seizures become worse and intractable; memory and psychological abnormalities appear. However, the neurosurgical cases may be the iceberg (~20%). The vast majority of cases (~80%) are not seen in these specialized centers and some of them may be very mild and easily controlled with proper AEDs.

Differential diagnosis
Non-epileptic conditions and seizures from other brain locations.

Management options
AEDs indicated for focal epilepsies. Early surgical intervention provides excellent chance of cure and subsequent normal life: ~60% become seizure free, 20% have reduced numbers of seizures, 10% show no benefit, and 10% have neurosurgical complications or get worse.

This page was adapted from:

The educational kit on epilepsies: The epileptic syndromes By C. P. Panayiotopoulos Originally published by MEDICINAE
21 Cave Street, Oxford OX4 1BA

First published 2006 and reprinted in 2007

Authored by: C. P. Panayiotopoulos MD PhD FRCP on 1/2005
Reviewed by: Steven C. Schachter MD on 6/2008
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