White matter microstructure and serum biomarkers of inflammation in psychogenic non-epileptic seizures

Functional Neurologic Disorder, La Lésion Dynamique: 2024 Wartenberg Lecture

Functional neurologic disorder is common and a significant cause of disability and stress in neurologic patients. The nature of this disorder has been unclear. Originally called hysteria, the disorder interested Charcot who postulated that a functional lesion, la lésion dynamique, was responsible. Recent studies of functional neurologic disorders now allow us to understand what la lésion dynamique is and identifies these disorders without ambiguity as arising from the brain. Functional neurologic disorders are best understood as a multifactorial process with a biopsychosocial model. There can be a genetic predisposition. Commonly there is early life trauma that leads to a developmental abnormality of the amygdala, including loss of inhibition. This abnormality can be considered a predisposing factor. When stressed, the amygdala becomes hyperactive, driving the limbic system to cause widespread network dysfunction in the brain. This dysfunction can improve, correlating with clinical improvement. Network dysfunction is becoming recognized as an important pathologic process in neurology and psychiatry, as real as any other pathology. We should be able to make progress in helping patients with functional neurologic disorders with this understanding of la lésion dynamique.

Peripheral and Central Nervous System Biomarkers of Inflammation in Functional Seizures: Assessment with Magnetic Resonance Spectroscopy

Purpose

Inflammation may link trauma to clinical symptoms in functional seizures (FS). We compared brain temperature and metabolites in FS, psychiatric (PCs) and healthy controls (HCs) and quantified their associations with serum biomarkers of inflammation and clinical symptoms.

Patients and Methods

Brain temperature and metabolites were measured with whole-brain magnetic resonance spectroscopic imaging (MRSI) and compared between groups in regions of interest and the whole brain. Relationships with inflammatory biomarkers and symptoms were assessed with Pearson correlations.

Results

Brain temperature was higher in FS than HCs in the orbitofrontal cortex (OFC) and anterior cingulate gyrus (ACG) and lower in the occipital cortex and frontal lobe. PCs showed lower temperatures than HCs in the frontal lobe including precentral gyrus and in the cerebellum. Myo-inositol (MINO) was higher in FS than HCs in the precentral gyrus, posterior temporal gyrus, ACG and OFC, and choline (CHO) was higher in the occipital lobe. CHO was higher in PCs than HCs in the ACG and OFC, and N-acetylaspartate (NAA) was higher in the ACG. There were no significant correlations with the serum inflammatory biomarkers. In FS, brain temperature correlated with depression, quality of life, psychological symptoms, and disability, CHO correlated with disability, and MINO correlated with hostility, disability, and quality of life.

Conclusion

Some of the previously identified neuroimaging abnormalities in FS may be related to comorbid psychiatric symptoms, while others, such as abnormalities in sensorimotor cortex, occipital regions, and the temporo-parietal junction may be specific to FS. Overlapping MINO and temperature increases in the ACG and OFC in FS suggest neuroinflammation.