Dataset Information

Semantic access dysphasia resulting from left temporal lobe tumours.

ABSTRACT: Unlike semantic degradation disorders, the mechanisms and the anatomical underpinnings of semantic access disorders are still unclear. We report the results of a case series study on the effects of temporal lobe gliomas on semantic access abilities of a group of 20 patients. Patients were tested 1-2 days before and 4-6 days after the removal of the tumour. Their semantic access skills were assessed with two spoken word-to-picture matching tasks, which aimed to separately control for rate of presentation, consistency and serial position effects (Experiment 1) and for word frequency and semantic distance effects (Experiment 2). These variables have been held to be critical in characterizing access in contrast to degraded-store semantic deficits, with access deficits characterized by inconsistency of response, better performance with slower presentation rates and with semantically distant stimuli, in the absence of frequency effects. Degradation deficits show the opposite pattern. Our results showed that low-grade slowly growing tumours tend not to produce signs of access problems. However, high-grade tumours especially within the left hemisphere consistently produce strong semantic deficits of a clear access type: response inconsistency and strong semantic distance effects in the absence of word frequency effects were detected. However, effects of presentation rate and serial position were very weak, suggesting non-refractory behaviour in the tumour patients tested. This evidence, together with the results of lesion overlapping, suggests the presence of a type of non-refractory semantic access deficit. We suggest that this deficit could be caused by the disconnection of posterior temporal lexical input areas from semantic system.

SUBMITTER: Campanella F

PROVIDER: S-EPMC2638694 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Semantic access dysphasia resulting from left temporal lobe tumours.

Campanella Fabio F Mondani Massimo M Skrap Miran M Shallice Tim T

Brain : a journal of neurology 20081202 Pt 1

Unlike semantic degradation disorders, the mechanisms and the anatomical underpinnings of semantic access disorders are still unclear. We report the results of a case series study on the effects of temporal lobe gliomas on semantic access abilities of a group of 20 patients. Patients were tested 1-2 days before and 4-6 days after the removal of the tumour. Their semantic access skills were assessed with two spoken word-to-picture matching tasks, which aimed to separately control for rate of pres ...[more]

PMID: 19050031

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Project description:Mesial temporal lobe epilepsy is the most common type of focal epilepsy and in its course often becomes refractory to anticonvulsant pharmacotherapy. A resection of the mesial temporal lobe structures is a promising option in these cases. However, approximately 30% of all patients remain with persistent seizures after surgery. In other words, reliable criteria for patients' outcome prediction are absent. To address this limitation, we investigated pre-surgical brain morphology of patients with unilateral left mesial temporal lobe epilepsy who underwent a selective amygdalohippocampectomy. Using support vector classification, we aimed to predict the post-surgical seizure outcome of each patient based on the pre-surgical T1-weighted structural brain images. Due to morphological gender differences and the evidence that men and women differ in onset, prevalence and symptomology in most neurological diseases, we investigated male and female patients separately. Thus, we benefitted from the capability to validate the reliability of our method in two independent samples. Notably, we were able to accurately predict the individual patients' outcome in the male (94% balanced accuracy) as well as in the female (96% balanced accuracy) group. In the male cohort relatively larger white matter volumes in the favorable as compared to the non-favorable outcome group were identified bilaterally in the cingulum bundle, fronto-occipital fasciculus and both caudate nuclei, whereas the left inferior longitudinal fasciculus showed relatively larger white matter volume in the non-favorable group. While relatively larger white matter volumes in the female cohort in the left inferior and right middle longitudinal fasciculus were associated with the favorable outcome, relatively larger white matter volumes in the non-favorable outcome group were identified bilaterally in the superior longitudinal fasciculi I and II. Here, we observed a clear lateralization and distinction of structures involved in the classification in men as compared to women with men exhibiting more alterations in the hemisphere contralateral to the seizure focus. In conclusion, individual post-surgical outcome predictions based on a single T1-weighted magnetic resonance image seem plausible and may thus support the routine pre-surgical workup of epilepsy patients.

Dataset Information

Semantic access dysphasia resulting from left temporal lobe tumours.

Publications

Semantic access dysphasia resulting from left temporal lobe tumours.

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