Multifocal hypometabolic correlates to deficits of verbal memory in mesial temporal lobe epilepsy

Racheal M Smetana; Prem P Batchala; Bern G Lee; Tamer Albataineh; Donna K Broshek; Nathan B Fountain; Salma Abbas; Mark Quigg

doi:10.1016/j.yebeh.2023.109244

Multifocal hypometabolic correlates to deficits of verbal memory in mesial temporal lobe epilepsy

Epilepsy Behav. 2023 Jun:143:109244. doi: 10.1016/j.yebeh.2023.109244. Epub 2023 May 14.

Authors

Racheal M Smetana¹, Prem P Batchala², Bern G Lee³, Tamer Albataineh⁴, Donna K Broshek⁵, Nathan B Fountain⁶, Salma Abbas⁷, Mark Quigg⁸

Affiliations

¹ Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA. Electronic address: rs8xs@uvahealth.org.
² Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA. Electronic address: ppb2f@uvahealth.org.
³ Department of Neuropsychology, Ochsner Health, Baton Rouge, LA, USA. Electronic address: bern.lee@ochsner.org.
⁴ Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA. Electronic address: ta2gd@uvahealth.org.
⁵ Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA. Electronic address: dkb6v@uvahealth.org.
⁶ Comprehensive Epilepsy Program, Department of Neurology, University of Virginia, Charlottesville, VA, USA. Electronic address: nbf2p@uvahealth.org.
⁷ Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA. Electronic address: soa9gj@uvahealth.org.
⁸ Comprehensive Epilepsy Program, Department of Neurology, University of Virginia, Charlottesville, VA, USA. Electronic address: msq6g@uvahealth.org.

PMID: 37192585
DOI: 10.1016/j.yebeh.2023.109244

Abstract

Background and objectives: Neuropsychological research on mesial temporal lobe epilepsy (MTLE) often highlights material-specific memory deficits, but a lesion-focused model may not accurately reflect the underlying networks that support episodic memory in these patients. Our study evaluated the pathophysiology behind verbal learning/memory deficits as revealed by hypometabolism quantified through 18-fluorodeoxyglucose positron emission tomography (FDG-PET).

Methods: This retrospective study included thirty presurgical patients with intractable unilateral MTLE who underwent interictal FDG-PET and verbal memory assessment (12 females, mean age: 38.73 years). Fluorodeoxyglucose-positron emission tomography mapping was performed with voxel-based mapping of glucose utilization to a database of age-matched controls to derive regional Z-scores. Neuropsychological outcome variables included scores on learning and recall trials of two distinct verbal memory measures validated for use in epilepsy research. Pearson's correlations evaluated relationships between clinical variables and verbal memory. Linear regression was used to relate regional hypometabolism and verbal memory assessment. Post hoc analyses assessed areas of FDG-PET hypometabolism (threshold Z ≤ -1.645 below mean) where verbal memory was impaired.

Results: Verbal memory deficits correlated with hypometabolism in limbic structures ipsilateral to language dominance but also correlated with hypometabolism in networks involving the ipsilateral perisylvian cortex and contralateral limbic and nonlimbic structures.

Discussion: We conclude that traditional models of verbal memory may not adequately capture cognitive deficits in a broader sample of patients with MTLE. This study has important implications for epilepsy surgery protocols that use neuropsychological data and FDG-PET to draw conclusions about surgical risks.

Keywords: 18F-FDG-PET; Epilepsy surgery; Mesial temporal lobe epilepsy; Neuropsychological assessment; Verbal memory.

MeSH terms

Adult
Epilepsy, Temporal Lobe* / complications
Epilepsy, Temporal Lobe* / diagnostic imaging
Epilepsy, Temporal Lobe* / psychology
Female
Fluorodeoxyglucose F18
Humans
Memory Disorders / diagnostic imaging
Memory Disorders / etiology
Memory, Episodic*
Positron-Emission Tomography / methods
Retrospective Studies

Substances

Fluorodeoxyglucose F18