Temporal lobe epilepsy (TLE) is the most common type of focal epilepsy syndrome, with often characteristic imaging and clinical findings. It is divided into two broad groups:
-
medial epilepsy
most common
involves the mesial temporal lobe structures
most frequently due to mesial temporal sclerosis
-
lateral epilepsy
involves the inferolateral and lateral neocortex of the temporal lobe
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Clinical presentation
Patients with temporal lobe epilepsy demonstrate three phases, each of variable duration and symptomatology:
preictal (aura) phase
ictal phase
postictal phase
Pre-ictal phase
A variable number of patients with temporal lobe epilepsy demonstrate or describe an aura, which is usually of short duration, and in most cases (70%) goes on to become a seizure 2. Auras are variable in symptomatology, and include:
-
viscerosensory aura
typically from lesions of the amygdala or insular cortex
-
psychic (experienced) aura
typically from limbic structures
variable including dysmnesic phenomena, cognoscitive phenomena, emotional phenomena, delusions, and hallucinations
Ictal phase
The majority of patients have a focal seizures with impaired awareness, during which a number of relatively specific features may be observed:
-
automatisms
stereotyped motor behaviors, typically of the mouth or hands
seen in 40-80% of cases 2
language alterations
unilateral dystonic posturing
versive head turning
Postictal phase
Postictal phase is also variable, and symptoms are largely determined by the location of the ictal lesion. Features include:
confusion
drowsiness
aphasia
psychiatric symptoms
Pathology
Temporal lobe epilepsy may be due to a veritable menagerie of causes including 1-3:
mesial temporal sclerosis (MTS): ~70%
-
temporal lobe tumors: ~10%
ganglioglioma is the most common
cortical dysplasia: 5-10%
trauma
infection
-
congenital
temporal pole encephalocele (rare) 4
Radiographic features
MRI is the modality of choice for structural imaging of the temporal lobe, and of course, appearances will depend on the underlying cause. These are discussed separately, thus please refer to:
-
infection
-
vascular malformations
It is essential to review the whole scan carefully as there is a high (5-20%) incidence of dual pathology, especially in cases of cortical dysplasia.
Treatment and prognosis
It is established that chronic medication-resistant epilepsy developed during childhood is linked to cognitive compromise and thus an early aggressive treatment and seizure control is advised for infants and young children 5.
Treatment depends on the etiology, but in most cases is primarily with antiseizure medications. In refractory cases, especially when a causative lesion can be identified, temporal lobectomy can be effective, provided cases are carefully selected.