Correct me if I am wrong, but can't deep brain epileptic seizures easily be missed with standard testing?
Yes, I think you're both right,
@alex3619 and
@Sidereal. When people bother to systematically compare the features of classic (tonic-clonic) epileptic seizures with this so-called "psychogenic" cluster (PNES), it all becomes very murky. From
Mostacci, B., Bisulli, F., Alvisi, L., Licchetta, L., Baruzzi, A., & Tinuper, P. (2011). Ictal characteristics of psychogenic nonepileptic seizures: what we have learned from video/EEG recordings—a literature review. Epilepsy & Behavior, 22(2), 144-153.
* The "psychogenic cluster", which is often defined on the basis of closure of the eyes during the episode, are consistently different from classic epileptic seizures (including frontal lobe seizures) in two ways:
1. Closure of eyes (not surprisingly, this is a commonly used criterion for definition)
2. Duration of episode (they may be considerably longer).
But other proposed differences are less clear:
"... EEG recording alone is not sufficient to diagnose PNES: an ictal scalp EEG may show no epileptic features during simple partial seizures or mesial frontal lobe seizures, and the latter may be easily mistaken for PNES.
"... preserved consciousness, out-of-phase limb movements, absence of whole-body rigidity throughout the spell, pelvic thrusting (especially forward), side-to-side head and body turning ... However, according to one study, in-phase limb movements may also be common in PNES. ...Moreover, it should be kept in mind that the aforementioned signs related to PNES are
common in frontal lobe seizures involving the mesial structures, so they have to be interpreted with caution.
"... incontinence and self-injury, especially if taken together, are highly specific for [classic] epileptic seizures, but in one series they were not uncommonly self-reported by patients with PNES. It is an established belief, as Gowers stated more than a century ago, that PNES never arise from sleep, but several authors have reported episodes arising from “pseudosleep” , and indeed, one single study reported rare cases of PNES arising from sleep.
Another confusing piece of evidence that sidereal notes is that some patients experience both types of seizures on different occasions (that is, sometimes classic ones, and sometimes "psychogenic" ones).
My conclusion: These so-called "psychogenic" seizures do seem to be qualitatively different to classic tonic-clonic seizures, but it is yet to be established whether their origin in psychogenic, or whether they reflect another, as yet uncharacterised neurological phenomenon.
What I see is a cluster of seizure-like events that have some unique properties (eye closure, duration, movement), but also share many properties with the "classic" cluster. Early psychogenic models may have biased researchers to focus upon divisions that are consistent with that way of thinking, at the expense of divisions that are inconsistent.