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Abstract
Temporal lobe epilepsy (TLE) was defined as a condition characterized by recurrent unprovoked seizures originating from the medial or lateral temporal lobe. The seizures associated with TLE consist of simple partial seizures without loss of awareness (with or without aura) and complex partial seizures (ie, with loss of awareness).
Auras occur in approximately 80% of temporal lobe seizures. They are a common feature of simple partial seizures and usually precede complex partial seizures of temporal lobe origin. Auras may be classified by symptom type; the types comprise somatosensory, special sensory, autonomic, or psychic symptoms. It has an important role in identifying the specific site and side of the epileptic focus e.g; Abdominal aura as epigastric sensation arising from amygdala while auditory aura arising from contralateral temporal lobe auditory cortex
Patients may experience depersonalization (ie, feeling of detachment from oneself) or derealization (ie, surroundings appear unreal) or Fear or anxiety usually is associated with seizures arising from the amygdala. Sometimes, the fear is strong, described as an ”impending sense of doom.” Patients may describe a sense of dissociation or autoscopy, in which they report seeing their own body from outside. These symptoms may complicate the diagnosis as it may be diagnosed as psychiatric disease.
Ictal seizure of TLE characterized by two main components: impaired consciousness and automatic behavior called as automatism. Automatism refers to motor behaviors occurring during complex partial seizures. The simplest and most common form is oro-alimentary automatism and consists of rhythmic chewing, swallowing or lip-smacking. Also there is hand automatism that may occur in one hand only and called unilateral manual automatism (UMA) indicating an ipsilateral epileptic focus however some studies denying its lateralizing value but when it is associated with dystonic posturing of contralateral upper limb it will have high lateralizing value. There is also lower limb automatism which is less frequently than upper limb behaviors, it can present fair lateralizing values. Dystonia of lower limb is considered to have the same lateralising value as the upper extremities. Also spitting automatism which is often described as a localizing and lateralizing sign, suggesting seizure onset in the language nondominant temporal lobe. Although Ictal automatisms are frequently considered as a consequence of impaired consciousness sometimes automatism occurs with preserved conscious lateralizing to nondominant hemisphere. Other movement as Hand and eye deviation, Pilomotor seizures, Rhythmic Ictal Nonclonic Hand (RINCH) Motions should be differentiated from automatism as every movement has its own localizing and lateralizing value.
Post ictal symptoms as post-ictal paresis and Post-ictal aphasia has an excellent lateralizing value in temporal lobe epilepsy. When present, its specificity is 100% in epilepsy of the dominant temporal lobe. However, the absence of post-ictal aphasia does not exclude that the epileptic focus is in the dominant temporal lobe. postictal automatism(PA) is a relatively frequent phenomenon in TLE and postictal speech automatism lateralizes the seizure onset zone in the left hemisphere.
Investigations should have harmony with each others and with clinical picture of the patient, usually EEG in patients with TLE show Interictal abnormalities, consisting of spike/sharp and slow complexes, usually are located in the anterior temporal region, and Ictal recordings EEG usually exhibit 5-7 Hz, rhythmic, sharp theta activity, maximal in the sphenoidal and the basal temporal electrodes on the side of seizure origin. EEG alone has limited role in the diagnosis of epilepsy, however the EEG can be very important for a correct delineation of the seizure type and/or the epileptic syndrome. In some situations, EEG findings are the key to diagnosis of the type of seizure and have a significant impact on the plane of treatment. Video EEG has an important role especially in persurgical evaluation also they may need intracranial EEG to detect the specific sit of the epileptic focus before surgery.
If neuroimaging studies need to be done MRI will be the best choice especially Tl- and T2-weighted images and FLAIR images. MRI shows hippocampal atrophy in 87% of patients with TLE by visual analysis alone. Hippocampal atrophy is bilateral in 10-15% of cases. An increase in the T2-weighted signal intensity in the hippocampus may be seen on (FLAIR) MRI; this finding is also consistent with hippocampal scleroses which consider the most common underlining pathology of TLE. Sometimes it is associated with second pathology as porencephalic cysts (30%), reactive gliosis (25%) and cortical dysgenesis (20%), but a lower incidence in association with vascular abnormalities (9%) or tumours (2%).
In patients with refractory temporal lobe epilepsy T2 relaxometry is done as it lateralize abnormalities correctly in 70% as the side of the seizure origin was ipsilateral to the hippocampal T2 abnormality when the abnormality was unilateral. When there were bilateral abnormalities with one side more abnormal than the other, the side of seizure origin also always correlated with the more abnormal hippocampal T2 signal.
Functional MRI as PET, SPECT is important especially in presurgical evaluation. Also simultaneous EEG and fMRI is considered now the most exciting new advances in epileptology and it may form form the basis of major new insights into mechanisms of seizure generation and epilepsy concepts.
Treatment of TLE is usually by AEDs as carbamazepine, phenytoin, valproic acid, lamotrigine, oxcarbazepine, gabapentin and topiramate but about one third of those patients are resistant to AEDs so surgical intervention as Vagus nerve stimulation or Anterior temporal lobectomy may be helpful.
So early detection of those patients and choosing suitable surgery for suitable patient by semiology of TLE means better prognosis and decrease the occurrence of complication that is directly related to the duration of the disease and numbers of fits especially the decline of cognitive function and memory which is very common with TLE. Also status epileptics may threaten the patient’s life.
Other complication like Injury from falls, bumps, biting self or injury from seizure occurring during driving or operating machinery or breathing fluid, such as saliva, during a seizure can cause pnumonia or Progression to generalized seizures also may occur. It was found that there is common comorbidity between TLE and psychiatric disease especilly depresion and it was found that the relationship between epilepsy and depression is ”bidirectional” with the presence of a common pathogenic process facilitating the occurrence of one disease in the presence of the other Supportive of this model is that similar structures of the limbic network are involved in both diseases also anxiety aggresion and psychosis may occur.
TLE In general speaking is chronic epilepsy that generally impairs cognition, and also induces processes of functional reorganization and behavioral compensations. Poor cognitive outcome is generally associated with early onset, long duration and poor seizure control. However the prognosis becomes better nowadays because of early surgical intervention by using semiological studies in detecting suitable patients.