Just wanted to emphasize we are not presuming to come out right, but rather that it seems available data is limited leaving a good number of theories open. So I want to keep discussion as open as possible, no need to ridicule me for it.
http://en.wikipedia.org/wiki/SSRI_discontinuation_syndrome#.22Brain_zaps.22_and_sensations
Symptoms described as "brain zaps", "brain shocks," "brain shivers", "head shocks" or "cranial zings" are a withdrawal symptom experienced during discontinuation (or reduction of dose) of antidepressant drugs.[8][9] The symptoms are widely variable in description and of unknown etiology;[9] common descriptions include dizziness, electric shock-like sensations, sweating, nausea, insomnia, tremor, confusion, nightmares and vertigo.[8][9] The MedDRA "preferred term" for coding these types of symptoms in adverse drug reaction reports (for use in pharmacovigilance databases such as under the Yellow Card Scheme) is paraesthesia.[10][11]
In a 1997 survey, a "sizable minority" of medical professionals were not confidently aware of the existence of antidepressant withdrawal symptoms.[12] A 2005 review of adverse event reporting showed that descriptions of "electric shocks" from patients on paroxetine had been reported more frequently than some other symptoms.[10]
So even if we only focus on SSRI discontinuation reactions there is vertigo or dizziness reported.
In my own experiences, the disorientation/vertigo/dizziness seems to be a direct result from very temporary suspension of awareness of your surroundings and basically centralized other brain functions it seems. It's no wonder reported effects can vary if they involve temporary suspension of partial or entire awareness. However it was not always like that for me. There was always a zapping (i.e. physical overload or peak type) sensation right alongside the suspension of spatial/temporal awareness. But sometimes it was mostly the zapping and much less of the loss of awareness, at least for me.
I have to say, there is an element that reminds me of ego loss, only one happening in the blink of an eye. Since it is so extremely transient, there is virtually none of the typical special sides of the character of ego suspension. Psychedelic ego-loss is a process and I have heard more than one people say that it is more the way to and from it that matters than the time you spend in ego-death. The reason is exactly because the suspension does not mean anything without a frame of reference.
http://pointofreturn.com/brain_zaps.html
The symptoms are described as brief but repeated electric shock-like sensations in the brain and head, or originating in the brain but extending to other parts of the body. Moving one’s eyes quickly from side to side has also been shown to trigger Brain Zaps in more rapid frequency. Brain Zaps are often accompanied by disorientation, tinnitus, vertigo and lightheadedness.
I'm not sure what kind of information you are after but as far as I know the exact process is not elucidated. On the other hand, it seems to me like plenty of people who stop SSRI use have experienced this so it's no bullshit.
Maybe you think it's not right to self-diagnose this, but personally I wonder how important that really is in threads like this. To actually earn a certain label or not is besides the point if you ask me. If you experienced zapping in your brain, read about the description like the ones above and identify with those it's enough for me. There seems to be a list of causes for this related to changes in serotonin levels so I don't think it's that vague at all.
What I agree with you is that it is hard to discuss this much further, though it depends on what the goal is that people posting here have. I would find it welcome if there comes a scientific explanation, until then I am satisfied to know there is a phenomenon that may involve a varying effect profile but generally stemming from having your serotonin levels fucked from SSRI's, MDMA, psychedelics and other drugs.
A good question IMO is: how related is the effect benzo discontinuation can have to this? Seizures are apparently possible, but are brain zaps as well? How close do they come to what people with SSRI discontinuation syndrome describe?