Prevalence
1/3 of TLE or 10% to 15% of all epilepsies.

Age at onset
Mainly late childhood to adolescence.

Sex
Males = females.

Neurological and mental state
Depends on etiology.

Etiology
Symptomatic, cryptogenic, idiopathic. Structural causes include malformations of cortical development, tumors, vascular, traumatic, viral and other infectious and parasitic disorders, and cerebrovascular disease.

Clinical manifestations
Seizures manifest with auditory hallucinations or illusions, vestibular phenomena, experiential symptoms, visual hallucinations, and visual misperceptions. Language disturbances in dominant hemispheric focus. Motor ictal symptoms include clonic movements of facial muscles, grimacing, finger and hand automatisms, dystonic posturing of an upper extremity, leg automatisms, restlessness, and unformed vocalizations. Rotation of the whole body is frequent and of differentiation value from mesial TLE.

These symptoms may progress to complex focal seizures through spreading to mesial temporal or extra-temporal structures. Impairment of consciousness is not as pronounced as with mesial TLE.

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

Complex focal status epilepticus occurs particularly in untreated patients. It is less common than absence status epilepticus of idiopathic generalized epilepsy.

Diagnostic procedures
MRI is abnormal in >90% of symptomatic cases.

Inter-ictal EEG
In symptomatic cases, background is usually abnormal, with posterior lateralized slow waves, and half show mid-temporal or posterior temporal spikes.

Ictal EEG
Rhythmic slow activity (around 4 to 7 Hz) that appears over the affected temporal lobe, before or simultaneously with clinical events. Fast spiking is more common in lateral TLE than in mesial TLE.

Prognosis
Frequency, severity, and response to treatment vary considerably from good to intractable and may be progressive, depending mainly on the underlying cause.

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

Lateral temporal lobe seizures usually lack features commonly exhibited in mesial TLE such as (1) ascending epigastric aura or fear; (2) eye blinking and aggressive behavior; and (3) contralateral dystonia, searching head movements, body shifting, hyperventilation, and post-ictal cough or sigh.

Management options
Drug treatment is similar to that for any other types of focal seizure.

Neurosurgical treatment provides an excellent chance of cure and a subsequent normal life in certain pathological conditions of lateral TLE.

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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