Diagnostic and Therapeutic Approach to Autoimmune Neurologic Disorders

A. Sebastian López-Chiriboga, MD; Eoin P. Flanagan, MD


Semin Neurol. 2018;38(3):392-402. 

In This Article

Functional Magnetic Resonance Imaging

Reduced functional connectivity of the left and right hippocampus with the anterior default mode network has been found in functional MRI of patients with anti-NMDA-R encephalitis along with prominent cingulum and extensive white matter changes on diffusion tensor imaging.[34]

2-deoxy-2-[Fluorine-18] Fluoro-D-glucose Integrated with Computed Tomography 18F-FDG PET/CT

FDG PET/CT is emerging as a very helpful tool in the diagnosis of neural antibody-mediated neurologic disorders.

Unilateral or bilateral striatal hypermetabolism is commonly found in patients with LGI-1 encephalitis.[17] Mesiotemporal lobe abnormalities (Figure 1C, D) are frequently identified in patients with autoimmune encephalitis associated with different cell surface antibodies.[35] A recent study showed that PET/CT is more often abnormal than paraclinical investigations such as electroencephalogram (EEG), MRI, and CSF in patients with autoimmune encephalitis, and it should be considered in the initial approach[36] but is limited by its higher cost, lack of specificity, and availability.

Cerebrospinal Fluid Analysis

CSF should be tested for markers of inflammation: white cell count, protein, oligoclonal bands, or IgG index. Elevation of these markers, although nonspecific, can support the diagnosis and provide helpful information for comparison to evaluate immunotherapy response (normalization or decreased number of white cells, etc.). A normal CSF does not exclude an autoimmune etiology for the neurologic presentation[16] (e.g., with LGI-1-antibody encephalitis, more than 70% have a noninflammatory CSF[37]).