Correlation between fluorodeoxyglucose positron emission tomography brain hypometabolism and posttraumatic stress disorder symptoms in temporal lobe epilepsy

Abstract

The relationship between posttraumatic stress disorder (PTSD) and focal epilepsy is poorly understood. It has been hypothesized that there is a complex and reciprocal potential reinforcement of the symptoms of each condition. In this study, we investigated whether there are PTSD-specific brain changes in temporal lobe epilepsy (TLE). Brain fluorodeoxyglucose positron emission tomography (PET) metabolism was compared between controls and two groups of TLE patients: one group of 15 patients fulfilling the criteria for a potential diagnosis of PTSD (TLE-PTSD+), another group of 24 patients without a diagnosis of PTSD (TLE-PTSD-), and a group of 30 healthy control participants. We compared the differences in brain PET metabolism among these three groups, and we studied their correlations with interictal and peri-ictal scales of PTSD symptoms. TLE-PTSD+ patients showed more significant hypometabolism involving right temporal and right orbitofrontal cortex in comparison to TLE-PTSD- patients and healthy subjects. Moreover, degree of reduced metabolism in these brain areas correlated with interictal and peri-ictal PTSD questionnaire scores. PTSD in temporal epilepsy is associated with specific changes in neural networks, affecting limbic and paralimbic structures. This illustrates the close intertwining of epileptogenic and psychogenic processes in these patients.

Keywords: PTSD; anxiety; temporal lobe epilepsy.

FIGURE 1

Hypometabolism in temporal lobe epilepsy (TLE) patients with posttraumatic stress disorder (PTSD) symptoms. (A) In comparison with healthy controls, patients with TLE exhibited significant hypometabolic brain regions, which was prominent in temporal regions (p‐voxel < .005). Right TLE and left TLE are shown. (B) TLE patients with PTSD symptoms exhibited significant brain fluorodeoxyglucose positron emission tomography (18F‐FDG‐PET) hypometabolism in comparison both to those without PTSD and to the healthy subjects (using inclusive mask), involving the right temporal pole and orbitofrontal cortex. (C) Correlation between the brain 18F‐FDG‐PET metabolic cluster and the PTSD symptom scores (Posttraumatic Diagnostic Scale for DSM‐5 [PDS‐5]) and PTSD symptom scores of the inter and peri‐ictal periods (Post‐Traumatic Stress Disorder for Epilepsy [PTSD‐E]).