Causes of epilepsy
There are many causes of epilepsy, which are usually divided into two categories: primary and secondary.
1. Primary
Primary epilepsy refers to the absence of organic or metabolic brain disease. The cause of epilepsy is still unclear, also known as occult epilepsy. Some of these epilepsies have no significant structural changes or metabolic abnormalities in the brain, but are related to genetic factors and have a tendency to occur familially, mostly in childhood and adolescence. Primary seizures are mostly generalized seizures, such as generalized tonic-clonic seizures, disoriented seizures and myoclonic seizures.
2.Secondary
Secondary seizures are caused by a variety of organic brain lesions or metabolic disorders.
(1) Congenital malformations: such as congenital hydrocephalus, microcephaly, corpus callosum hypoplasia, cerebral cortical hypoplasia, etc.
(2) Prenatal and weaning disorders: birth injury is a common cause of orthostatic epilepsy in infancy.
(3) Sequelae of febrile convulsions: Severe and prolonged febrile convulsions can lead to brain damage including neuronal loss and gliosis, mainly in the medial temporal lobe, especially in the hippocampus.
(4) Craniocerebral injury: the most common cases produce early epileptic seizures within a few weeks after injury.
(5) Infection: seen in various central nervous system infections. The acute phase can be manifested as one of the clinical symptoms, the late phase can be left with seizures, seizures can be in the form of generalized or partial acute infection in addition to seizures in the acute phase, in the recovery period can also be left with brain softening, atrophic lesions and recurrent seizures. In chronic cases, there may be partial or generalized seizures during the progression of the disease.
(6) Poisoning: lead, mercury, carbon monoxide, ethanol, turtle, isoniazid poisoning, and systemic diseases such as gestational hypertensive syndrome and uremic syndrome can cause seizures.
(7) Intracranial tumor cerebrovascular disease: Except for cerebrovascular malformation and subarachnoid hemorrhage which produce epilepsy at a younger age, post-stroke epilepsy is mostly seen in middle-aged and elderly people. Hypertensive encephalopathy is also often associated with epilepsy.
(8) Nutritional and metabolic diseases: In adults, hypoglycemia due to islet cell tumors, diabetes mellitus, hyperthyroidism, hypoparathyroidism, and vitamin B6 deficiency can lead to seizures.
(9) Degenerative diseases: Epilepsy is one of the main manifestations of tuberous sclerosis. Alzheimer’s disease is also often associated with epilepsy.
What are a few misconceptions about epilepsy general knowledge?
Myth 1: If a patient convulses, it is epilepsy.
Convulsions are one of the main symptoms of epilepsy, but they are not unique to epilepsy. Other diseases can also cause convulsions, such as miasmatic spasms, hypocalcemic convulsions, pediatric hyperthermia convulsions, hypoglycemic convulsions, etc. are not part of epilepsy. Therefore, convulsions may not always be due to epilepsy. Also, some types of epilepsy do not have convulsion symptoms, such as aphasic seizures, temporal lobe epilepsy, ventral epilepsy, and headache epilepsy. Therefore, convulsions should not be equated with epilepsy.
Myth 2: Large convulsive movements are grand mal seizures and small movements are petit mal seizures.
Both grand mal and petit mal seizures are generalized seizures. The size of the seizure is not differentiated by the magnitude of the convulsive movements. A grand mal seizure has a generalized twitching of the limbs, while a typical petit mal seizure has only a brief (no more than 1 minute) loss of consciousness and no convulsive movements. Some patients or family members identify all other forms of seizures other than generalized grand mal seizures as petit mal seizures, which is obviously inaccurate. The clinician has to accurately classify and reasonably select drugs based on the patient’s medical history and onset symptoms in order to receive better results.
Myth 3: When a seizure occurs, the patient has a loss of consciousness.
The most important thing is to make sure that the patient is aware of the situation. Therefore, the diagnosis of epilepsy should not be denied because the patient has a loss of consciousness and treatment is delayed.
Myth 4: Primary epilepsy is associated with genetics, while secondary epilepsy has nothing to do with genetics.
A large number of surveys of epileptic patients and their blood relatives have found that not only is primary epilepsy associated with heredity, but the prevalence of immediate relatives with secondary epilepsy is much higher than the general population. Clinically related, patients who have had traumatic brain injury, encephalitis, meningitis, or a history of birth asphyxia do not always develop epilepsy. This suggests that the occurrence of epilepsy depends not only on the strength of environmental factors, but also on the genetic factors that determine it.
Genetics determines the “convulsive threshold” for a person to have a seizure, and the lower the threshold, the more likely the person is to have a seizure. If the strength of environmental factors exceeds the convulsive threshold, epilepsy will occur, which means that not only primary epilepsy but also secondary epilepsy has some heritability.