Epilepsy is generally caused by abnormal electrical discharges in the brain, and the possible mechanisms by which the brain produces seizures include the following:
Excitatory synaptic inhibition is enhanced
When the abnormal high-frequency repeated discharge produces a large excitatory postsynaptic potential in the neurons directly connected with the axons, the continuous propagation of epileptic discharges occurs. Abnormal discharges are confined to a certain area and manifest as partial seizures, causing secondary generalized seizures when the abnormal discharge extends not only to the ipsilateral hemisphere but even to the contralateral hemisphere.
Inhibitory mechanisms in the brain
The nervous system has a complex excitatory and inhibitory feedback mechanism to maintain the stability of nerve cell membranes, and epilepsy is the enhancement of the excitatory process and the weakening of the inhibitory process.
Endogenous neuronal burst discharge
Endogenous neuronal burst discharges are usually characterized by increased voltage-dependent calcium currents, some localized seizures appear to be predominantly loss of inhibitory neurons, and primary generalized absence seizures may be due to diffuse synchronous spike-slow wave activity due to increased voltage-dependent calcium currents in thalamic neurons.
What are the effects of abnormal electrical discharges on the brain during seizures?Different seizure types have different effects on the brain:
Generalized Grand Mar Attack:According to relevant statistics, about 40%-45% of patients with generalized mal attacks have intellectual disabilities in mathematics, phonics, literacy and reading. The main reason is that the patient has difficulty concentrating, and has poor visual spatial orientation and continuous work ability.
Infantile spasms:As a type of epilepsy unique to infancy and early childhood, infantile spasms not only has a mortality rate of 13%, but also has more than 90% intellectual disability due to its early onset age and special form of convulsions. Studies have shown that the earlier the age of onset of the disease, the more serious the harm caused. Common injuries include speech impairment, partial blindness, strabismus, and paralysis of limbs.
Temporal lobe seizures:Previous studies have found that both immediate and delayed memory in patients with temporal lobe seizures** are compromised to varying degrees. When the patient has a left temporal lobe lesion, the memory impairment of the language item is worse;When the lesion is in the right temporal lobe, the patient's ability to recall nonverbal items immediately is poor. However, several recent studies have concluded that there is no significant difference in the location of temporal lobe lesions for memory of verbal or nonverbal items. The definitive conclusions are still being debated, but it is certain that temporal lobe seizures have an impact on the cognitive function of patients.
Absence seizures:Absence seizures, as a type of generalized seizures in epilepsy, are relatively easy to control and have a good prognosis. However, this does not mean that the impact on brain function will be particularly small. The study found that patients had difficulty in learning Xi mathematics and pinyin when they had a generalized mal attack, and the number of repeaters was more than 3 times that of normal children, and they would repeat grades many times, especially in children who started before the age of 7. 