Ictal SPECT in Psychogenic Nonepileptic and Epileptic Seizures, 2020, Gallucci-Neto et al

[Andy]

Psychogenic nonepileptic seizures (PNES) are a common and debilitating problem in patients with epilepsy. They can be virtually indistinguishable from epileptic seizures, demanding video-electroencaphalogram monitoring, which is costly and not widely available, for differential diagnosis. Specific functional brain correlates of PNES have not been demonstrated so far. We hypothesized that PNES and epileptic seizures have distinct brain activation patterns, assessed by functional neuroimaging during ictal events of both conditions. Objective: Compare ictal brain activation patterns of PNES and epileptic seizures using single-photon emission computerized tomography.

Methods
We prospectively assessed brain functional activation using single-photon emission computerized tomography 99mTc-ethyl cysteinate dimer in 26 patients with PNES, confirmed by trained psychiatrists in epileptology, who had their seizures induced by provocative tests compared with 22 age- and sex-matched subjects with temporal lobe epilepsy who underwent prolonged intensive video-electroencaphalogram monitoring.

Results
In PNES patients compared with temporal lobe epilepsy group, we found a consistent increase in regional cerebral blood flow in the right precuneus (Brodmann area 7; P = 0.003) and right posterior cingulate cortex (Brodmann area 31; P = 0.001), as well as a decrease in regional cerebral blood flow in the right amygdala (P = 0.027).

Conclusions
Activation of default model network brain areas and temporoparietal junction may be a distinct feature of ictal PNES and could be explained by a disruption between movement prediction input and sensory outcome. Such information mismatch might be the neurobiological underpinning of dissociative episodes.

Paywall, https://www.sciencedirect.com/science/article/abs/pii/S0033318220301560
Sci hub, https://sci-hub.tw/10.1016/j.psym.2020.05.016

 

[Mithriel]

Activation of default model network brain areas and temporoparietal junction may be a distinct feature of ictal PNES and could be explained by a disruption between movement prediction input and sensory outcome. Such information mismatch might be the neurobiological underpinning of dissociative episodes.

I found the paper difficult to understand, though it did not seem to be deliberately obscure like some of the BPS stuff, so I could be wrong in my interpretation. They seem to assume conversion disorder when a biological interpretation is just as likely to be correct. All their findings are taken as proof of the reality of hysteria rather than proof of a biological fault. Damage to the stress responsive parts of the brain so the system does not work properly does not mean that changing your thoughts is relevant.

Take ulcers. My mother was told she had a nervous stomach after a life threatening bleed from her ulcer. For years she had to watch what she ate and try to stay calm. They were not wrong - oranges made her ulcer worse and stress did too but it turned out that a bacteria made her stomach not work properly. After a course of antibiotics she could eat as many oranges as she liked and get seriously stressed without any stomach pain.