Executive deficits in neuropsychological testing differentiate between autoimmune temporal lobe epilepsy caused by limbic encephalitis and temporal lobe epilepsies with non-autoimmune etiologies

Nadine Conradi; Marion Behrens; Annika Schuster; Sophia Schmitt; Nina Merkel; Nico Melzer; Saskia Elben; Kai Siebenbrodt; Adam Strzelczyk; Felix Rosenow

doi:10.1016/j.yebeh.2021.108378

Executive deficits in neuropsychological testing differentiate between autoimmune temporal lobe epilepsy caused by limbic encephalitis and temporal lobe epilepsies with non-autoimmune etiologies

Epilepsy Behav. 2021 Oct 26:124:108378. doi: 10.1016/j.yebeh.2021.108378. Online ahead of print.

Authors

Affiliations

¹ Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, University Hospital Frankfurt and Goethe University, Frankfurt am Main, Germany; LOEWE Center for Personalized Translational Epilepsy Research (CePTER), Goethe University, Frankfurt am Main, Germany. Electronic address: Nadine.Conradi@kgu.de.
² Department of Neurology, University Hospital Frankfurt and Goethe University, Frankfurt am Main, Germany.
³ Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, University Hospital Frankfurt and Goethe University, Frankfurt am Main, Germany.
⁴ Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, University Hospital Frankfurt and Goethe University, Frankfurt am Main, Germany; LOEWE Center for Personalized Translational Epilepsy Research (CePTER), Goethe University, Frankfurt am Main, Germany.
⁵ Department of Neurology, Medical Faculty, Heinrich Heine-University of Düsseldorf, Düsseldorf, Germany.

PMID: 34715429
DOI: 10.1016/j.yebeh.2021.108378

Abstract

Objective: Patients with temporal lobe epilepsy caused by autoimmune limbic encephalitis (AI-TLE) clinically resemble patients with temporal lobe epilepsy with non-autoimmune etiologies (NAI-TLE) but have a different prognosis and require specific adjusted therapies. The objective of this study was to investigate whether patients with these forms of TLE can be discerned by means of neuropsychological assessment.

Methods: Data from 103 patients with TLE (n = 39 with AI-TLE and n = 64 with NAI-TLE, including n = 39 with hippocampal sclerosis [HS] and n = 25 with low-grade epilepsy-associated tumors [LEAT]) and 25 healthy controls who underwent comprehensive neuropsychological assessments were analyzed retrospectively. The neuropsychological characteristics (mean z-scores) were compared between groups using one-way ANOVA, independent-samples t-tests, and discriminant function analysis (DFA).

Results: The groups of patients with TLE showed significantly lower performance in attentional, visuospatial, verbal memory, and nonverbal memory functions compared to the healthy controls. Solely in the domain of executive functions, patients with AI-TLE showed significantly lower performance compared to patients with NAI-TLE regarding cognitive flexibility (p = 0.002) and verbal fluency (p = 0.018). Moreover, the DFA identified cognitive flexibility to be most appropriate to differentiate between patients with AI-TLE and patients with HS. Group membership was correctly predicted through neuropsychological assessment alone in 66.7% of the patients using cross-validation.

Significance: We were able to identify specific neuropsychological features in our sample of patients with AI-TLE. While all groups of patients with TLE showed the expected TLE-typical memory impairments, significant differences between patients with AI-TLE and NAI-TLE were present only in the cognitive domain of executive functions. This finding facilitates the choice of suitable psychometric tests in clinical routine and, thus, the clinical differential diagnosis between these entities.

Keywords: Autoimmune temporal lobe epilepsy; Deficits in executive functions; Hippocampal sclerosis; Limbic encephalitis; Low-grade epilepsy-associated tumors; Neuropsychology.