Neuroimaging abnormalities in functional/dissociative seizures: a meta-analysis

The neural basis of functional/dissociative seizures represents a significant challenge for psychiatry and neurology. While abnormalities in neuroimaging have been observed, findings across studies remain inconsistent. This systematic review and meta-analyses examined neuroimaging abnormalities in functional/dissociative seizures, conducting separate meta-analyses of cortical thickness and whole-brain, seed-based, resting-state functional connectivity. A total of 22 studies were included in the review, of which seven and three were suitable for meta-analysis of structural and functional MRI data, respectively. Meta-analysis of cortical thickness from seven structural MRI studies (198 functional/dissociative seizures and 254 healthy controls) revealed a reduction in the right calcarine fissure/surrounding cortex (z = -3.08, p < 0.01) and right precentral gyrus (z = -3.112, p < 0.01). Additionally, the whole-brain seed-based resting-state functional connectivity analysis from three functional MRI studies (48 patients with functional/dissociative seizures and 64 healthy controls) demonstrated increased connectivity between seeds in the sensorimotor network (including posterior insula, paracentral lobule, postcentral gyrus, supplementary motor area and superior temporal gyrus) and areas of the ventral attention network, including left thalamus (z = 3.73, p < 0.01) and left putamen (z = 3.62, p < 0.01); and seeds in the default mode network (including ventral anterior insula, superior frontal gyrus and middle temporal gyrus) exhibited heightened connectivity with the left insula (z = 4.01, p < 0.01). These findings indicate structural and functional abnormalities in visual, sensorimotor, default mode, and attentional areas and networks associated with functional/dissociative seizures, highlighting potential neurobiological mechanisms. Further research is necessary to elucidate the complex interplay of clinical features and comorbidities, which will enhance our understanding of the pathophysiology of functional/dissociative seizures.