"[5] 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.

[8] 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.

According to "Harrison's Manual of Medicine," the EEG during the tonic phase will show a "progressive increase in low-voltage fast wave activity, followed by generalized high-amplitude, poly spike discharges.

"[2] The clonic phase EEG will show "high amplitude activity that is typically interrupted by slow waves to create a spike-and-slow-wave pattern.

"[2] Additionally, the postictal phase will show suppression of all brain activity, then slowing that gradually recovers as the patient awakens.

Due to this lack of specificity in describing the onset of a seizure and being considered an archaic term, it is not typically used by medical professionals.