Temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common type of partial epilepsy, with often characteristic imaging and clinical findings. It is divided into two broad groups:

1. medial epilepsy
   • most common
   • involves the mesial temporal lobe structures
   • most frequently due to mesial temporal sclerosis
2. lateral epilepsy
   • involves the inferolateral and lateral neocortex of the temporal lobe

Pathology

Temporal lobe epilepsy may be due to a veritable menagerie of causes including ^1-3:

• mesial temporal sclerosis : 70%
• temporal lobe tumours : 10%
  • ganglioglioma : most common
• cortical dysplasia(s) : 5 - 10%
• vascular malformations : 5%
• trauma
• infection

Clinical presentation

Patients with temporal lobe epilepsy demonstrate three phases, each of variable duration and symptomatology. 

1. preictal (aura) phase
2. ictal phase
3. post-ictal phase

Pre-ictal phase

A variably number of patients with temporal lobe epilepsy demonstrate or describe an aura, which is typically of short duration, and in most cases (70%) goes on to become a seizure ². Auras are variable in symptomatology, and include:

• viscero-sensory aura
  • typically from lesions of the amygdala or insular cortex
• psychic (experienced) aura
  • typically from limbic structures
  • variable including dymnesic phenomena, cognoscitive phenomena, emontional phenomena and illusions and hallucinations

Ictal phase

The majority of patients have a complex partial seizure, during which a number of relatively specific features may be observed:

• automatisms
  • stereotyped motor behaviours, typically of the mouth or hands
  • seen in 40 - 80% of cases ²
• language alterations
• unilateral dystonic posturing
• versive head turning

Post-ictal phase

Post ictal phase is also variable, and symptoms are largely determined by the location of the ictal lesion. Features include:

• confusion
• drowsiness
• aphasia
• psychiatric symptoms

Radiology

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 :

• mesial temporal sclerosis
• temporal lobe tumours
• cortical dysplasia
• infection
  • meningitis
  • HSV encephalitis
• vascular malformations
  • cavernous malformation
  • AVM

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

Treatment depends on the aetiology, but in most cases is primarily with antiepileptic medications. In refractory cases, especially when a causative lesion can be identified, temporal lobectomy can be effective, provided cases are carefully selected.