Temporal lobe epilepsy is considered to be one of the most common types of epilepsy. Structures that constitute the mesial temporal lobe, primarily hippocampus, are hypothesized to be the origin of excitatory signals. Cognition, memory and functional ability are all impaired as a result of seizure activity. Imaging studies and EEG confirm the diagnosis, whereas treatment is primarily surgical, as this form of epilepsy is resistant to antiepileptics.
The clinical presentation of patients suffering from TLE starts with partial seizures and the appearance of an aura. Epigastric sensations, fear, deja vu or olfactory hallucinations are forms of aura that are encountered in these patients and are quite common . In neonates and infants, however, these auras may be difficult to attain and recognize . Seizures are characterized by arrest of motor behavior, blank stare, and automatisms . At some point, symptoms that indicate memory loss, executive function, language deficits and various other impairments . Both autobiographical and working memory loss has been observed , whereas significant disability may be seen as a result of slowed mental processing speed, mood and personality disorders, as well as extensive changes in emotional responses  . Namely, failure to recognize fear, sadness and disgust have been observed, which may be used as indicative signs of temporal lobe involvement . Interictal (the period between seizures) depression is diagnosed in up to one third of patients , suggesting that this condition carries a significant psychological burden.
The initial diagnosis of epilepsy can be made based on clinical criteria, whereas a confirmation of TLE can be made through the following methods  :
Temporal lobe epilepsy is not responsive to pharmacotherapy, which shifts the focus of management to surgery. The goal is to completely excise and remove the zone in which the epileptic signal originates , and procedures such as anterior temporal lobectomy (ATL) or selective amygdalohippocampectomy (SAH) are indicated . With successfully resected regions, many patients become seizure-free, but a small percentage is left with some form of disability, as neurosurgery carries a minor, but significant risk of brain injury. For resection to be complete and successful, a thorough preoperative assessment guided by EEG and imaging studies is detrimental . In the case of bilateral hippocampal involvement, the risks and benefits of surgery should be discussed.
The prognosis of patients with successful surgical therapy is very good , and marked reduction or even disappearance of seizure activity can be achieved. The diagnosis of TLE, however, is often delayed for a considerable amount of time, which correlates with a poorer prognosis. TLE is practically nonresponsive to pharmacological therapy and precious time is often used on attempting to find the appropriate antiepileptic regimen. In fact, studies have identified that it takes up to 9 or even 10 years for surgical therapy to be instated , while some reports suggest that more than 20 years elapse prior to confirming TLE . The importance of choosing the optimal surgical approach also has important prognostic factors in long-term management of patients, due to the fact that neurosurgical procedures are quite sensitive and may result in further damage. For these reasons, a careful and detailed pre-operative assessment through imaging modalities and EEG is necessary.
Although the exact cause of epilepsy in general remains incompletely understood, the principal source of aberrant signaling in the case of TLE is the hippocampus , which undergoes sclerosis, atrophy and neuronal loss, with similar effects seen in the amygdala and parahippocampal gyri. As a result, diffuse pathological changes are observed in the morphology and structure . TLE has shown to be strongly associated with several conditions  :
In addition to these conditions, a hypothesis that some previous condition in early childhood triggered the pathological sequence has been suggested as well. Febrile seizures, birth injuries and status epilepticus have shown to be present in a substantial amount of patients who developed TLE, suggesting that other factors may also play a role in etiology .
Global estimations suggest that the prevalence of all forms of epilepsy combined reach up to 1% of the population , with significant variations across the world. In developed countries, prevalence rates are approximately 1 per 1000 individuals, whereas developing countries have shown rates of up to 50 per 1000 individuals . In general, epilepsy is most frequently encountered in young children and the elderly , but early childhood and adolescence is considered to be the principal age of onset . TLE is the most common form of partial seizures, which comprise almost 60% of all cases of epilepsy, with estimations that of 1,200,000 Americans who suffer from epilepsy, 400,000 are affected by TLE . Exact prevalence and incidence rates of TLE, however, are unknown at this moment . In addition to diseases that are mentioned as potential causes of TLE, such as cortical dysplasia, tumors and vascular malformations , febrile seizures during infancy and birth injuries have also been identified as potential risk factors for later development of TLE .
The most common and most important pathological finding in patients with TLE is atrophy and sclerosis of the hippocampus , one of the constitutive parts of the mesial temporal lobe, together with the amygdala, uncus, parahippocampal and dentate gyri. Presumably, hippocampal sclerosis and atrophy are a result of neuronal loss that occurs in the temporal lobe and cause disruption of signaling, causing enhanced excitation and hypersynchronnous discharge of neurons in that area that eventually lead to epilepsy . In addition, various pathophysiological processes have been described - loss of interneurons, impaired neurogenesis and mossy fiber sprouting (branching of additional neurons) . The exact mechanism of epilepsy, however, is still not completely understood.
Current prevention strategies do not exist, as the exact pathophysiological mechanism of TLE remains unknown. Given the fact that recent evidence about the involvement of inflammatory changes in seizures have been published, anti-inflammatory drugs, but also growth hormone secretagogues have been proposed as potentially preventing agents . Further studies, however, need to be conducted in order to determine the exact role of inflammation and other pathophysiological events in the development of TLE.
Partial-onset seizures comprise almost 60% of all epilepsies and temporal lobe epilepsy (TLE) is the most common form of partial seizures worldwide . Of approximately 1,200,000 people suffering from partial seizures in the United States, TLE is the cause in more than 400,000, indicating its importance in clinical practice . Theories regarding its etiology are numerous, but various studies have established that in up to a third of patients, some preexisting condition is thought to be the trigger for abnormal excitatory signaling in the mesial temporal lobe  . Tumors, cortical dysplasia, vascular malformations, head trauma and encephalomalacia have all been discovered in a significant amount of patients who developed TLS . Hence, these conditions present as significant risk factors for its appearance, but the exact pathophysiological mechanisms remain to be fully disclosed. The principal pathological findings are hippocampal sclerosis, neuronal damage and atrophy, which leaves a detrimental effect on various processes, including memory, cognition and motor function . Additional structures that constitute the mesial temporal lobe - the amygdala, uncus, dentate gyrus and parahippocampal gyrus, have all shown similar pathological degradation and are also considered as potential sources of epileptic signaling . The clinical presentation somewhat varies across different age groups (partly due to a varying etiology between the pediatric, adolescent and adult population), but universally includes partial seizures and the presence of auras (olfactory, epigastric or gustatory sensations). Memory and attention impairments, as well as reduced speed of mental function, mood changes and emotional abnormalities appear at some point and can be severely debilitating . The initial diagnosis of epilepsy is made based on clinical findings, but imaging and electroencephalographic (EEG) studies are necessary to identify the exact origin of aberrant signals. Magnetic resonance imaging (MRI) is an effective diagnostic method, whereas single photon emission computed tomography (SPECT) and positron emission tomography (PET) may be considered when MRI findings are inconclusive . Both invasive and noninvasive EEG studies, including video EEG are equally necessary as imaging studies and the combination of findings is imperative in determining the exact site of epileptic signals . Because TLE is resistant to antiepileptic drugs (AEDs) in virtually all cases, a surgical approach as early as possible is advocated to assure a good quality of life and reduce functional impairment . With either complete resection or removal of the structures in the mesial temporal lobe, much better outcomes have been encountered , which is why a prompt definite diagnosis by using all available tools and surgery can significantly reduce the burden of this condition in daily life.
Epilepsy is considered to be a major issue in clinical practice, as estimates suggest that 1% of the world population suffers from any of the recognized forms. Temporal lobe epilepsy (TLE) one of the most common causes, with more than 400,000 people who live in the United States are presumed to suffer from TLE. This form of epilepsy is established to be one of the most severe, since it does not respond to antiepileptic drugs and requires other therapeutic modalities. The exact cause of TLE remains to be discovered, but in up to 30% of patients, an accompanying structural abnormality such as brain tumors or cortical dysplasia has been identified. Studies have observed loss of neuronal function and atrophy of the hippocampus, one of the most important parts of the brain when it comes to memory, whereas the amygdala (principally responsible for emotions such as fear) may be affected as well. TLE may appear at any age, but it's onset is primarily seen in young children. The first and most important symptom is seizures that involve only one brain hemisphere (partial seizures) and the arrest of motor activity with a blank stare during the onset of seizures. They may be followed or preceded by auras (strange sensations in the stomach, deja-vu or visual and auditory hallucinations), together with various neurological complaints. Patients with TLE may suffer from memory loss, inability to perform daily functions, language difficulties and severe cognitive disability. The diagnosis is made through the use of imaging studies such as magnetic resonance imaging (MRI) and positron emission tomography (PET scan), together with eletroencephalography (EEG). These methods are used to visualize and map the exact location where abnormal signaling occurs, which is necessary for treatment. In the case of TLE, surgery is the recommended therapeutic method. In general, removal of parts of the brain that are determined to be the source of epileptic signals is necessary and early surgery has shown drastic success in reducing or completely abolishing the appearance of seizures. Despite the advantages of surgery, the diagnosis is delayed in many patients due to attempts to handle seizures with antiepileptic drugs, which is why a detailed diagnostic workup is essential.