Գլխավոր Հիվանդություններ Temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is a chronic disorder of the nervous system characterized by recurrent, unprovoked focal seizures (also known as partial seizures) that originate in the temporal lobe of the brain and last about one or two minutes. TLE is the most common form of epilepsy with focal seizures. People with TLE may experience simple partial seizures that only affect the temporal lobe or complex partial seizures that spread to other regions of the brain. During simple partial seizures, some people remain conscious. Depending on the areas of the brain affected, people with TLE may experience chest discomfort, nausea, unexplained emotions (e.g., intense joy or fear), or loss of awareness (e.g., staring or repetitive behaviors like blinking, twitching, pacing, etc.). They might also be in a dream-like state and have changes in consciousness, strange sensations, or have hallucinations and see, hear, feel, smell, or taste things that are not real. Some people report auras (warnings that a seizure is approaching), usually described as intense feelings of déjà vu or fear. Usually auras are actually the focal seizure itself, but some people do develop a regular progression of symptoms before each seizure that can serve as a warning. TLE is usually diagnosed in childhood or by the teenage years. Physicians diagnose TLE by taking a medical history, blood tests, and brain imaging (EEG, CT scan, PET, and/or MRI). It can have a number of causes such as head injury, stroke, brain infections, structural lesions in the brain, or brain tumors, or it can be idiopathic and have no apparent cause. The first line of treatment is through anticonvulsant medication. Surgery may be an option for some people, especially when there is an observable abnormality in the brain. Another treatment option is electrical stimulation of the brain through an implantation called the vagus nerve stimulation (VNS) device.

Types Over forty types of epilepsy are recognized and these are divided into two main seizures: Partial seizure and generalized seizure. Partial seizures account for approximately sixty percent of all adult cases. Temporal lobe epilepsy (TLE) is the single most common form of partial seizure. The International League Against Epilepsy (ILAE) recognizes two main types of temporal lobe epilepsy: mesial temporal lobe epilepsy (MTLE), arising in the hippocampus, the parahippocampal gyrus and the amygdala which are located in the inner (medial) aspect of the temporal lobe and lateral temporal lobe epilepsy (LTLE), the rarer type, arising in the neocortex at the outer (lateral) surface of the temporal lobe.The seizures of LTLE are characterized by auditory or visual features. Autosomal dominant Lateral Temporal Lobe Epilepsy (ADLTLE) is a rare hereditary condition. In 2013, the ILAE published a new classification of MTLE based on abnormalities (hippocampal sclerosis) found at the microscopic level in the tissue of the hippocampus. However, the pathology changes used in the classification cannot easily be predicted by clinical features. Signs and symptoms When a seizure begins in the temporal lobe, its symptoms and the patient's behavior as seen by bystanders, depend on the precise location of its point of origin, its locus. In 1981, the ILAE recognized three types of seizures occurring in temporal lobe epilepsy. The classification was based on EEG findings. Simple partial seizures Simple partial seizures (SPS) involve small areas of the temporal lobe such as the amygdala and hippocampus. The term simple means that the level of consciousness of the patient is not altered during the seizure. In temporal lobe epilepsy, a simple partial seizure usually causes abnormal sensations only. These may be mnestic sensations such as déjà vu (a feeling of familiarity), jamais vu (a feeling of unfamiliarity); amnesia; or a single memory or set of memories; auditory (an abnormal sound or tune); gustatory (an abnormal taste); olfactory (a smell that is not physically present); visual; or sensory (involving feelings on the skin or in the internal organs) sensations. Sensory disturbances may seem to move over the body. Synesthesia (stimulation of one sense experienced in a second sense) may transpire. Dysphoric or euphoric feelings, fear, anger, and other emotions may also occur. Often, the patient cannot describe the sensations. Simple partial seizures may be called auras by lay people who mistake them for a warning sign of a subsequent seizure. Instead, the so-called aura is actually the partial seizure itself. People who only experience simple partial seizures may not recognize what they are, nor seek medical advice about them.A simple partial seizure may or may not progress to any of the seizure types listed below. Complex partial seizures Complex partial seizures (CPS) are seizures which impair consciousness to some extent: they alter the person's ability to interact normally with their environment. They usually begin with a single partial seizure, then spread to a larger portion of the temporal lobe, resulting in impaired consciousness. Signs may include motionless staring, automatic movements of the hands or mouth, altered ability to respond to others, unusual speech, or other unusual behaviors. These seizures tend to have a warning or aura before they occur, and when they occur they generally tend to last only 1–2 minutes. It is not uncommon for an individual to be tired or confused for up to 15 minutes after a seizure has occurred. Though they may not seem harmful, due to the fact that the individual does not normally seize, they can be extremely harmful if the individual is left alone around dangerous objects. For example, if a person with complex partial seizures is driving alone, this can cause them to run into the ditch, or worse cause an accident involving multiple people. With this type, some people do not even realize they are having a seizure and most of the time their memory from right before or after the seizure is wiped. First-aid is only required if there has been an injury or if this is the first time a person has had a seizure. Secondarily generalized tonic-clonic seizures Seizures which begin in the temporal lobe, and then spread to involve the whole brain are known as Secondarily Generalized Tonic-Clonic Seizures (SGTCS). The arms, trunk, and legs stiffen (the tonic phase), in either a flexed or extended position, and then jerk (the clonic phase). Secondarily generalized tonic clonic seizures are known in the vernacular as convulsions or grand mal seizures. The word grand mal comes from the French term, meaning major affliction. Postictal period There is some period of recovery in which neurological function is altered after each of these seizure types. This is the postictal state. The degree and length of postictal impairment directly correlates with the severity of the seizure type. Simple partial seizures often last less than sixty seconds; complex partial seizures may last up to two minutes; and generalized tonic clonic seizures may last up to three minutes.[citation needed] The postictal state in the case of complex partial seizures and generalised tonic clonic seizures, the postictal state may last much longer than the seizure itself. Because a major function of the temporal lobe is short-term memory, complex partial seizures and generalised tonic clonic seizures may cause amnesia for the period of the seizure. As a result, patients with temporal lobe complex partial seizures and generalised tonic clonic seizures may not remember having had a seizure. Interictal period Investigations which examine cerebral blood flow show a reduction in the perfusion of the ipsilateral temporal lobe between seizures in patients with intractable TLE. These investigations include H(2)(15)O positron emission tomography (PET) scanning and pulsed arterial spin labeling MR imaging. Causes The causes of TLE include mesial temporal sclerosis, traumatic brain injury, brain infections, such as encephalitis and meningitis, hypoxic brain injury, stroke, cerebral tumours, and genetic syndromes. Temporal lobe epilepsy is not the result of mental health disorders or fragility of the personality. Febrile seizures Although the theory is controversial, there is a link between febrile seizures (seizures coinciding with episodes of fever in young children) and subsequent temporal lobe epilepsy, at least epidemiologically. Human herpes virus 6 In the mid 1980s, human herpesvirus 6 (HHV-6) was suggested as a possible causal link between febrile convulsions and mesial temporal lobe epilepsy. However, although the virus is found in temporal lobe tissue at surgery for TLE, it has not been recognised as a major factor in febrile seizures or TLE. Reelin Dispersion of the granule cell layer in the hippocampal dentate gyrus is occasionally seen in temporal lobe epilepsy and has been linked to the downregulation of reelin, a protein that normally keeps the layer compact by containing neuronal migration. It is unknown whether changes in reelin expression play a role in epilepsy. Aberrant mossy fiber sprouting Mossy fibers are the axons of Ponte nuclei cells. They project into the hilum of the dentate gyrus and stratum lucidum in the CA3 region giving input to both excitatory and inhibitory neurons. In the TLE brain, where granule cells are damaged or lost, axons, the mossy fibres, 'sprout' in order to reconnect to other granule cell dendrites. This is an example of synaptic reorganisation. This was noted in human tissue in 1974 and in animal models in 1985. In TLE, the sprouting mossy fibres are larger than in the normal brain and their connections may be aberrant. Mossy fibre sprouting continues from one week to two months after injury.(p416–431) Aberrant mossy fibre sprouting may create excitatory feedback circuits that lead to temporal lobe seizures. This is evident in intracellular recordings. Stimulation of aberrant mossy fibre areas increases the excitatory postsynaptic potential response. However, aberrant mossy fiber sprouting may inhibit excitatory transmission by synapsing with basket cells which are inhibitory neurons and by releasing GABA and neuropeptide Y which are inhibitory neurotransmitters. Also, in animal models, granule cell hyper-excitability is recorded before aberrant mossy fibre sprouting has occurred.

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