Autoimmune Limbic Encephalitis: A Review of Clinicoradiological Features and the Challenges of Diagnosis

Abstract

Limbic encephalitis is an autoimmune cause of encephalitis. In addition to the usual symptoms of encephalitis such as altered consciousness, fever, and focal neurological deficits, limbic encephalitis can present with neuropsychiatric manifestations and seizures. Making a formal diagnosis involves a difficult and prolonged workup phase. The purpose of this review is to help readers delineate limbic encephalitis from other illnesses. This is done by presenting a spectrum of potential organic differential diagnoses and pertinent findings that distinguish them from limbic encephalitis. Instead of presenting a variety of psychiatric differential diagnoses, the authors present a review of psychiatric manifestations known to be associated with limbic encephalitis, as naturally, any psychiatric disorder could be a potential comorbid disease.

Keywords: autoimmune encephalitis; limbic encephalitis; neuroimaging; neuroradiology; receptor antibodies.

Figure 1. Diagram of the limbic system and its nearby structures

Limbic encephalitis results in inflammation of the cingulate cortex, frontobasal cortex, hippocampus, and medial temporal lobe (image in the public domain). Source: [9]

Figure 2. Example of anti-CASPR2 encephalitis demonstrated

(a) MRI-3T, T2-FLAIR axial and coronal slices showing medial temporal hyperintensity as well as swelling, predominantly on the right side; (b) Corresponding 18F-FDG-PET/CT axial and coronal slices showing right medial temporal hyperactivity (licensed under CC BY-ND 4.0) [72] CASPR2 = contactin-associated protein-like 2, FLAIR = fluid-attenuated inversion recovery, 18F-FDG-PET = 18F-fluorodeoxyglucose-positron emission tomography