Neuropsychological Evaluations in Limbic Encephalitis

Abstract

Limbic encephalitis (LE) can cause dynamic and permanent impairment of cognition and behavior. In clinical practice, the question arises as to which cognitive and behavioral domains are affected by LE and which assessment is suited to monitor the disease progress and the success of treatment. Current findings on cognition and behavior in LE are reviewed and discussed based on current guidelines and consensus papers. In addition, we outline approaches for the neuropsychological monitoring of LE and its treatment. Dependent on disease acuity and severity, LE leads to episodic long-term memory dysfunction in different variants (e.g., anterograde memory impairment, accelerated long-term forgetting, and affection of autobiographical memory) and executive deficits. In addition, affective disorders are very common. More severe psychiatric symptoms may occur as well. In the course of the disease, dynamic phases with functional recovery must be differentiated from residual defect states. Evidence-based neuropsychological diagnostics should be conducted ideally before treatment initiation and reassessments are indicated when any progress is suggested, and when decisive anti-seizure or immunomodulatory treatment changes are made. Cognition and behavior may but must not run in synchrony with seizures, MRI pathology, or immune parameters. Cognitive and behavioral problems are integral aspects of LE and represent important biomarkers of disease acuity, progress, and therapy response beyond and in addition to parameters of immunology, neurological symptoms, and brain imaging. Thus, evidence-based neuropsychological assessments are essential for the diagnostic workup of patients with suspected or diagnosed limbic encephalitis, for treatment decisions, and disease and treatment monitoring.

Keywords: assessment; auto-antibodies; autoimmune epilepsy; behavior; cognition; diagnostics; limbic encephalitis; memory; monitoring; neuropsychology.

Figure 1

Exemplary cases demonstrating the cognitive monitoring of patients with limbic encephalitis (LE). The figures show the neuropsychological course and immunomodulatory treatments in (A) a patient with LGI1-positive LE and (B) a patient with GAD65-positive LE. The left y-axis refers to the cognitive performances which are presented in standard values. The below average range (i.e., a standard values below 90) is highlighted in grey. The right y-axis refers to the Beck Depression Inventory (BDI) score. A BDI score >10 would indicate depressed mood.