The vast majority of<unk>  seizures are idiopathic. Some<unk>  seizures start as a smaller seizure that occurs solely on one side of the brain, however, and is referred to as a focal (or partial) seizure. These unilateral seizure types (formerly known as simple partial seizure or a complex partial seizure and now referred to as focal aware seizure and focal impaired awareness seizure, respectively) can then spread to both hemispheres of the brain and cause a<unk> . This type of seizure has a specific term called "focal to bilateral<unk><unk>  seizure." Other precipitating factors include chemical and neurotransmitter imbalances and a genetically or situationally determined seizure threshold, both of which have been implicated. The seizure threshold can be altered by fatigue, malnutrition, lack of sleep or rest, hypertension, stress, diabetes, the presence of strobe-flashes or simple light/dark patterns, raised estrogen levels at ovulation, fluorescent lighting, rapid motion or flight, blood sugar imbalances, anxiety, antihistamines and other factors.<unk><unk><unk>  seizures can also be induced deliberately with electroconvulsive therapy. In the case of symptomatic epilepsy, the cause is often determined by MRI or other neuroimaging techniques showing that there is some degree of damage to a large number of neurons. The lesions (i.e., scar tissue) caused by the loss of these neurons can result in groups of neurons forming a seizure "focus" area with episodic abnormal firing that can cause seizures if the focus is not abolished or suppressed via anticonvulsant drugs.
Generalized tonic–clonic seizure
Reflex seizure
Intercalated seizure
Absence seizure
Focal seizure
Atonic seizure
Status epilepticus
Febrile seizure