Limbic neurochemical changes in patients with functional motor symptoms

Objective To assess by magnetic resonance spectroscopy (MRS) the N-acetylaspartate, myo-inositol, choline, sum of glutamate and glutamine (Glx), and creatine (Cr) content in the anterior cingulate cortex (ACC)/medial prefrontal cortex (mPFC) and in the occipital cortex (OCC) (control region) in patients with functional motor symptoms (FMS) and healthy controls, and to determine whether neurochemical limbic changes as estimated by MRS correlate with FMS-related motor symptom severity, alexithymia, anxiety, depression, and quality of life. Methods This case-control study enrolled 10 patients with FMS and 10 healthy controls. Participants underwent MRS and were tested with the Mini-Mental State Examination, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, 20-Item Toronto Alexithymia Scale, and EuroQol 5D. Results In patients with FMS, MRS showed increased Glx/Cr in the ACC/mPFC but normal content in the control OCC. All the other metabolites tested were normal in both regions. The increased Glx/Cr content in the ACC/mPFC correlated with alexithymia, anxiety, and severity of symptoms. Conclusions The abnormal limbic Glx increase could have a crucial pathophysiologic role in FMS, possibly by altering limbic-motor interactions, ultimately leading to abnormal movements.