Learning and Memory Impairment in Patients with Temporal Lobe Epilepsy: Relation to the Presence, Type, and Location of Brain Lesion

Abstract

Summary:Purpose: To study the influence of epileptogenic lesions on learning and memory alterations in patients with temporal lobe epilepsy (TLE).Methods: We studied 131 patients (55 with left and 39 with right lesional TLE; 22 with left and 15 with right cryptogenic TLE) and 36 healthy subjects. We compared these groups by using a battery of tests to assess verbal and visual learning, delayed recall, and recall after the imposition of interfering activity.Results: Compared with the controls and patients with right TLE, the patients with left TLE were significantly impaired on all verbal tests. On visual tests, patients with right TLE were impaired compared with controls but not more so than patients with left TLE. Separate multivariate analyses of variance (MA-NOVAS) of patients' verbal and visual test scores, taking the TLE side and morphologic features of the temporal lobes (i.e., normal, hippocampal sclerosis, low-grade glioma, or cavernous angioma) as independent factors, did not show any significant effect of these features. Separate comparisons of verbal and visual test scores of patients with lesional TLE, taking the side and location (mesial or lateral) of the epileptogenic lesion as independent factors, did not show any significant effect of location.Conclusions: Our findings show that some learning and memory abilities are impaired in patients with TLE irrespective of the presence of overt damage. This supports the theory that focal epileptic discharges, rather than the lesions themselves, affect these functions. The pathologic characteristics and intratemporal location of an associated lesion do not seem to play an important role in determining learning and memory impairment when clinical and treatment-related factors are taken into account. Key Words: Temporal lobe epilepsy-LesionLearning-Memory .Learning and memory difficulties are the most frequent cognitive alterations in patients with temporal lobe epilepsy (TLE) (1). Memory abilities in TLE are influenced by the presence of interictal epileptic discharges not associated with overt seizures (2), age at seizure onset, disease duration, seizure frequency (3), anxiety, depression (4), and antiepileptic drug (AED) treatment (5). However, the role of focal brain lesions (as distinct from focal epileptic discharges) has not been clearly established.Deutsch (6) found that patients with epilepsy with and without overt brain damage were similarly impaired on learning and memory tests, whereas Klove and Matthews (7) reported worse performances in patients with lesional

Comorbidity of Anxiety and Affective Disorders as Neuropsychiatric and Evolutionary Problem (A New Concept)

“…Notably, the similar results are observed irrespective of epilepsy form, i.e. as in cryptogenic, as in symptomatic temporal lobe epilepsy (Giovagnoli & Avanzini, 1999). In other words, the brain organic lesion itself, including mesiotemporal sclerosis, isn't enough to explain aforementioned discrepancies in hemisphere functions.…”

“…The left hemisphere seems to be responsible as for analytic and verbal, as for gestalt function, while the right hemispherestrictly for gestalt functions. Based on their findings authors concluded that lateralization of brain functions concerns strictly the verbal, but not the visual functions (Giovagnoli & Avanzini, 1999). Concluding this part of article we may suggest that TLE with left foci is more virulent than with right foci, because it causes deterioration as in verbal, as in nonverbal functions.…”

Learning and memory and its relationship with the lateralization of epileptic focus in subjects with temporal lobe epilepsy

“…Several authors, however, found no learning and memory deficits in MTLE patients with unilateral lesions located on the right hemisphere, although confirming the existence of episodic learning and memory deficits for verbal content in MTLE affecting the left hemisphere [11][12][13][14][15] .…”

Carbamazepine Enhances Discriminative Memory in a Rat Model of Epilepsy

“…Verbal or visuoconstructive memory dysfunction has been found in patients with left temporal epilepsy or right temporal epilepsy, respectively (4). In preclinical studies, spatial memory of temporal lobe epileptic rats is shown to be compromised (5,6).…”