Nobody really knows what causes seizures. It is hard to discount the cumulative effect of long-term etizolam abuse in evaluating your
susceptibility, but...
I have no idea how I got there, no memory of taking the 5-meo-DALT
We just don't know. Anywho, the fact that you were on high doses of barbiturates prior to etiz serves mostly to reinforce the theory that some cumulative effect of sedative abuse made you more susceptible to seizures. The effect of GABAergic abuse is cumulative rather than acute; the drugs cause long-term changes in brain structure:
http://en.wikipedia.org/wiki/Effects_of_long-term_benzodiazepine_use#Mental_and_physical_health
http://www.benzo.org.uk/ashbzoc.htm
But this is far afield from my realm of experience.
http://en.wikipedia.org/wiki/Epileptic_seizure#Mechanism
Wikipedia said:
Normally brain electrical activity is non synchronous. In epileptic seizures, due to problems within the brain, a group of neurons begin firing in an abnormal, excessive, and synchronized manner. This results in a wave of depolarization known as a paroxysmal depolarizing shift.
Normally after an excitatory neuron fires it becomes more resistant to firing for a period of time. This is due in part from the effect of inhibitory neurons, electrical changes within the excitatory neuron, and the negative effects of adenosine. In epilepsy the resistance of excitatory neurons to fire during this period is decreased.[10] This may occur due to changes in ion channels or inhibitory neurons not functioning properly. This then results in a specific area from which seizures may develop, known as a "seizure focus".[10] Another cause of epilepsy may be the up regulation of excitatory circuits or down regulation of inhibitory circuits follow an injury to the brain. These secondary epilepsies, occur through processes known as epileptogenesis. Failure of the blood–brain barrier may also be a causal mechanism
The primary function of benzodiazepines is to increase the sensitivity of the inhibitory chloride ion channel linked to the GABA receptor type A. When these receptors are overstimulated, the brain tries to decrease both the number of such ion channels and their sensitivity, producing tolerance. It also increases the availability of stimulating glutamate receptors.
The effect of psychedelics is to increase the sensitivity of certain excitatory receptors in the prefrontal cortex. Normally these receptors are triggered in response to novelty, but on a psychedelic they are triggered much more readily. The subject perceives things as being novel, leading to both an appreciation of everyday life (I'm lucky just to live in a world where avocados exist) and disillusion with coping mechanisms, which stop functioning as coping mechanisms and seem like independent phenomena (on LSD you'll drink the whisky slowly and think about how much it's hurting you). This happens because the signalling cascade is activated more easily.
Normally, the brain is kind of disorganized, not in sync. But when you take a drug, it affects the whole brain, at once, because it bypasses the normal mechanisms that control neurotransmitter levels -- that's why our favorite drugs are the ones that penetrate the blood-brain barrier, which turns out to be there for a reason. This is itself a sort of synchronization. Especially if the drug is snorted, or otherwise administered rapidly (smoking, injection), in which case the brain undergoes the infamous "rush". It's probably not good to get a rush if you've already drained your psychic brake fluid.
My layperson interpretation is that the seizure starts like hydroplaning: as long as some tiny shred of the brain is still touching the proverbial Earth, it functions as an anchor. But once you cross a sort of "threshold", the car lifts further off the road as water is forced under the tire. And if you have no brakes... hardcore benzo addicts probably shouldn't take stimulants. You get unlucky, then you're wrapped around a tree... you were at risk of a seizure for years, but that's just it,
at risk. It happens or it doesn't. My understanding is that a whole lot of drugs can be a trigger:
LSD,
methamphetamine, et cetera.
As for the duration of the seizure, a likely story is the extent of damage you had already done to yourself.