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Anything that injures a region of the brain can lead to a seizure focus, but in more than half of cases no such injury or cause for the seizures can be identified. We infer the presence in such cases of a subtle injury or an imbalance of excitatory and inhibitory neurotransmitters in the brain.
The type of injury that may lead to a seizure is age-dependent.
Seizures originating in children often are caused by birth traumas, infections such as meningitis, congenital abnormalities, or high fevers.
Seizures in the middle years commonly are caused by injuries from head trauma, infections, alcohol, stimulant drugs, or side effects of medication. Pregnant women can have seizures from eclampsia (toxemia) and related conditions.
Scientists and clinicians increasingly recognize the importance of genetic factors in the origin of epilepsy. Genetics are most relevant to generalized seizures, including absence, generalized tonic-clonic, and myoclonic seizures. Defects in genes do not lead directly to epilepsy, but they can alter the excitability of brain in a way to predispose to seizures.
In the elderly, brain tumors and strokes cause a higher proportion of seizures. Nevertheless, any cause can produce seizures at almost any age, and the most common etiology (cause) at any age remains unknown. The medical term for unknown is "idiopathic."
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