Psychiatric symptoms and comorbidities in patients with drug-resistant epilepsy in presurgical assessment-A prospective explorative single center study.

Introduction: People with epilepsy (PWE) have a higher prevalence of psychiatric disorders. Some individuals with drug-resistant epilepsy might benefit from surgical interventions. The aim of this study was to perform an assessment of psychiatric comorbidities with a follow-up period of 12 months in patients with drug-resistant epilepsy, comparing those who underwent surgery to those who did not. Material and methods: We assessed psychiatric comorbidities at baseline, after 4 months and after 12 months. Psychiatric symptoms and diagnoses were assessed using SCID-Interview, Hamilton Rating Scale for Depression, Beck-Depression Inventory, Hamilton Anxiety Rating Scale, Prodromal-Questionnaire and the Global Assessment of Functioning Scale. Results: Twenty-five patients were included in the study, 12 underwent surgery, 11 were esteemed as being neurologically unqualified for surgery and two refused surgery. Patients in the no-surgery group were significantly older, reported more substance use, had significantly higher levels of anxiety and were more often diagnosed with a personality disorder. Age and levels of anxiety were significant predictors of being in the surgery or the no-surgery group. The described differences between surgery and no-surgery patients did not change significantly over the follow-up period. Discussion: These data point toward a higher expression of baseline psychiatric symptoms in drug-resistant PWE without surgery. Further studies are warranted to further elucidate these findings and to clarify potential psychotropic effects of epilepsy itself, drug-resistant epilepsy and of epilepsy surgery and their impact on psychopathology. Clinically, it seems highly relevant to include psychiatrists in an interdisciplinary state-of-the-art perioperative management of drug-resistant PWE.

Fully Integrated PET/MR Imaging for the Assessment of the Relationship Between Functional Connectivity and Glucose Metabolic Rate.

In the past, determination of absolute values of cerebral metabolic rate of glucose (CMRGlc) in clinical routine was rarely carried out due to the invasive nature of arterial sampling. With the advent of combined PET/MR imaging technology, CMRGlc values can be obtained non-invasively, thereby providing the opportunity to take advantage of fully quantitative data in clinical routine. However, CMRGlc values display high physiological variability, presumably due to fluctuations in the intrinsic activity of the brain at rest. To reduce CMRGlc variability associated with these fluctuations, the objective of this study was to determine whether functional connectivity measures derived from resting-state fMRI (rs-fMRI) could be used to correct for these fluctuations in intrinsic brain activity. METHODS: We studied 10 healthy volunteers who underwent a test-retest dynamic [18F]FDG-PET study using a fully integrated PET/MR system (Siemens Biograph mMR). To validate the non-invasive derivation of an image-derived input function based on combined analysis of PET and MR data, arterial blood samples were obtained. Using the arterial input function (AIF), parametric images representing CMRGlc were determined using the Patlak graphical approach. Both directed functional connectivity (dFC) and undirected functional connectivity (uFC) were determined between nodes in six major networks (Default mode network, Salience, L/R Executive, Attention, and Sensory-motor network) using either a bivariate-correlation (R coefficient) or a Multi-Variate AutoRegressive (MVAR) model. In addition, the performance of a regional connectivity measure, the fractional amplitude of low frequency fluctuations (fALFF), was also investigated. RESULTS: The average intrasubject variability for CMRGlc values between test and retest was determined as (14 ±8%) with an average inter-subject variability of 25% at test and 15% at retest. The average CMRGlc value (umol/100 g/min) across all networks was 39 ±10 at test and increased slightly to 43 ±6 at retest. The R, MVAR and fALFF coefficients showed relatively large test-retest variability in comparison to the inter-subjects variability, resulting in poor reliability (intraclass correlation in the range of 0.11-0.65). More importantly, no significant relationship was found between the R coefficients (for uFC), MVAR coefficients (for dFC) or fALFF and corresponding CMRGlc values for any of the six major networks. DISCUSSION: Measurement of functional connectivity within established brain networks did not provide a means to decrease the inter- or intrasubject variability of CMRGlc values. As such, our results indicate that connectivity measured derived from rs-fMRI acquired contemporaneously with PET imaging are not suited for correction of CMRGlc variability associated with intrinsic fluctuations of resting-state brain activity. Thus, given the observed substantial inter- and intrasubject variability of CMRGlc values, the relevance of absolute quantification for clinical routine is presently uncertain.