A study of word finding difficulties in Spanish speakers with temporal lobe epilepsy

It is well established that naming deficits can be found in temporal lobe epilepsy (TLE). The aim of this study was to determine in Spanish speakers with pharmacoresistant TLE the characteristics of subjective naming difficulties and to examine performance in a definition task and a picture task in left TLE and right TLE. We observed that almost one-third of patients report frequent and severe word finding problems during spontaneous speech. In naming tests, our patients exhibited delayed times for finding words. Even if the target word was identified and semantically activated, there was difficulty with lexical access, which improved when a phonetic cue was given. Left TLE patients derived a lower benefit from phonetic cues in accessing words, even when the word is known and recognized semantically. These findings were not related to any demographic or clinical characteristics analyzed. The fact that the only weakly lateralized variable has been a lexical access facilitation measurement could support a lexical access hypothesis for naming deficits in TLE.     

Recognition and identification of famous faces in patients with unilateral temporal lobe epilepsy.

We examined the performance of 21 patients with unilateral temporal lobe epilepsy (TLE) and hippocampal damage (10 lefts, and 11 rights) and 10 age-matched controls on the recognition and identification (name and occupation) of well-known faces. Famous face stimuli were selected from four time periods; 1970s, 1980s, 1990-1994, and 1995-1996. Differential patterns of performance were observed for the left and right TLE group across distinct face processing components. The left TLE group showed a selective impairment in naming famous faces while they performed similar to the controls in face recognition and semantic identification (i.e. occupation). In contrast, the right TLE group was impaired across all components of face memory; face recognition, semantic identification, and face naming. Face naming impairment in the left TLE group was characterized by a temporal gradient with better naming performance for famous faces from more distant time periods. Findings are discussed in terms of the role of the temporal lobe system for the acquisition, retention, and retrieval of face semantic networks, and the differential effects of lateralized temporal lobe lesions in this process.     

Auditory naming and temporal lobe epilepsy.

Patients with left (i.e. language-dominant) temporal lobe epilepsy (TLE) typically report word finding difficulties. However, these deficits are not reliably detected with traditional visual object naming tests. We administered both visual and auditory naming tests to left and right TLE patients and normal controls. We hypothesized that an auditory naming test might be more sensitive since it better simulates the conditions under which word finding problems occur in daily living. The left TLE group obtained significantly lower scores than other groups on auditory naming, whereas their performance on visual naming was indistinguishable from that of right TLE patients and normals. Furthermore, whereas cut-off scores on the auditory naming task predicted seizure focus laterality in 85% of patients, performance on the visual naming task predicted laterality in only 60% of patients. These findings suggest that compared with visual naming, as assessed in the present study, auditory naming may more accurately characterize and lateralize TLE-associated language dysfunction. These results also propose a more complex understanding of word retrieval that incorporates modality and contextual information.     

Model based prognosis of postoperative object naming in left temporal lobe epilepsy

Epilepsy surgery in the left temporal lobe is associated with a high risk of naming decline. In the present study, in 45 patients with left temporal lobe epilepsy (TLE) and confirmed left hemisphere language dominance, 13 (29%) patients demonstrated postoperative decrement >or=5 naming failures in the Boston Naming Test (BNT). Multivariate discriminant analysis with age at onset of epilepsy, age at first risk, age at operation and preoperative naming performance as predictors indicated that 12 (92%) patients with later naming decline could be identified preoperatively. Univariate group comparisons revealed that specifically patients with seizure onset later than 14 years without preceding risk factors (e.g., febrile seizures) are in danger of postoperative dysnomia. It is hypothesized, that there is a strong connection between stable naming performance and deviant intrahemispheric speech representation as a result of early brain damage and/or chronic seizures.     

Advantages of sentence-level fMRI language tasks in presurgical language mapping for temporal lobe epilepsy

fMRI language mapping has become increasingly utilized for determining language dominance before surgical intervention for temporal lobe epilepsy (TLE). This study aimed to examine the differences between two classes of fMRI word generation tasks used in our clinic: tasks using a single word cue, referred to as simple generative tasks (SGTs), and tasks also involving sentence-level processing, referred to as sentence-level language tasks (SLTs). Specifically, we aimed to investigate the extent and laterality of activation and frontal–temporal connectivity during these language tasks and their relationship to clinical language measures. Thirty-one patients with TLE (18 patients with left TLE and 13 patients with right TLE) performed four language tasks during an fMRI scan, two SGTs and two SLTs. We found significantly greater activity for SLTs over SGTs in bilateral inferior frontal and middle temporal gyri and the left temporal pole. Sentence-level language tasks also showed greater lateralization compared with SGTs. Finally, we found that while activation extent did not correlate with clinical language tests, the degree of left frontal–temporal connectivity was significantly correlated with naming and semantic fluency performance. These correlations also were more robust for SLTs than for SGTs. Taken together, these results provide a compelling argument for including some form of SLTs in fMRI language lateralization protocols for TLE as they allow for better characterization of language networks, particularly in the temporal lobes which are at risk in surgery.     

Preoperative assessment of confrontation naming ability and interictal paraphasia production in unilateral temporal lobe epilepsy

The present study examined the diagnostic utility of confrontation naming tasks and phonemic paraphasia production in lateralizing the epileptogenic region in patients with temporal lobe epilepsy (TLE). Further, the role of intelligence in moderating the diagnostic utility of confrontation naming tasks was assessed. Eighty patients with medically intractable complex partial seizures (40 left TLE, 40 right TLE) received the Boston Naming Test (BNT) and the Visual Naming subtest (VNT) of the Multilingual Aphasia Examination. The BNT was diagnostically more sensitive than the VNT in identifying left TLE (77.5% vs 17.5%, respectively). The utility of BNT performance and paraphasias was maximal in patients with Full Scale IQs >or=90 who were 6.8 times more likely to have left TLE than patients without paraphasias. Preoperative assessment of confrontation naming ability and phonemic paraphasia production using the BNT provided diagnostically useful information in lateralizing the epileptogenic region in left TLE.     

Memory for famous faces and the temporal pole: functional imaging findings in temporal lobe epilepsy

The ability to recognize, name, and provide information about famous persons is deficient in patients with temporal lobe epilepsy (TLE), although the neural basis for these deficits is not well understood. We examined the relationship of resting metabolism of the temporal poles, as determined by [18F] fluorodeoxyglucose positron emission tomography, to performance on a task of famous face recognition, naming, and generation of semantic information in 12 patients with TLE. Correlations between metabolic measures of the temporal poles and performance on the Famous Faces Task revealed strong relationships between all aspects of the Famous Faces Task and the left temporal pole, whereas Famous Faces Task correlations with the right temporal pole were not significant. These findings indicate that the left temporal pole is associated with lexical and semantic retrieval of knowledge of famous persons in patients with TLE. Further study appears warranted to elucidate the networks involved in semantic knowledge for famous faces.     

Hyperfamiliarity in patients with temporal lobe epilepsy

Hyperfamiliarity is a type of paramnesia characterized by an increased feeling of familiarity to unfamiliar faces. This dysfunction has been associated with frontal and temporal lobe pathology. The study investigated hyperfamiliarity in patients with temporal lobe epilepsy (TLE) by assessing their ability to recognize both familiar and unfamiliar faces. We evaluated 61 patients with pharmacoresistant TLE (33 right-sided, 28 left-sided) and 16 controls. The ability to recognize familiar faces was similar in patients and controls, although patients with left-sided TLE showed poorer performance in familiar face naming compared to both right-sided TLE patients and controls. Hyperfamiliarity was observed in a significantly higher number of patients with TLE compared to controls; in subgroup analysis, only right-sided TLE patients expressed hyperfamiliarity. Overall, patients with right-sided TLE showed more severe impairment compared to patients with left-sided TLE. It is proposed that hyperfamiliarity can be a relatively common symptom in patients with treatment-refractory TLE and right-sided focus.     

Imaging language networks before and after anterior temporal lobe resection: results of a longitudinal fMRI study

Purpose: Anterior temporal lobe resection (ATLR) controls seizures in up to 70% of patients with intractable temporal lobe epilepsy (TLE) but, in the language dominant hemisphere, may impair language function, particularly naming. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated reorganization of language in left‐hemisphere–dominant patients before and after ATLR; whether preoperative functional magnetic resonance imaging (fMRI) predicts postoperative naming decline; and efficiency of postoperative language networks. Methods: We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left) on a 3T GE‐MRI scanner. All subjects performed language fMRI and neuropsychological testing preoperatively and again 4 months after left or right ATLR. Key Findings: Postoperatively, individuals with left TLE had greater bilateral middle/inferior frontal fMRI activation and stronger functional connectivity from the left inferior/middle frontal gyri to the contralateral frontal lobe than preoperatively, and this was not observed in individuals with right TLE. Preoperatively, in left and right TLE, better naming correlated with greater preoperative left hippocampal and left frontal activation for verbal fluency (VF). In left TLE, stronger preoperative left middle frontal activation for VF was predictive of greater decline in naming after ATLR. Postoperatively, in left TLE with clinically significant naming decline, greater right middle frontal VF activation correlated with better postoperative naming. In patients without postoperative naming decline, better naming correlated with greater activation in the remaining left posterior hippocampus. In right TLE, naming ability correlated with left hippocampal and left and right frontal VF activation postoperatively. Significance: In left TLE, early postoperative reorganization to the contralateral frontal lobe suggests multiple systems support language function. Postoperatively, ipsilateral recruitment involving the posterior hippocampal remnant is important for maintaining language, and reorganization to the contralateral hemisphere is less effective. Preoperative left middle frontal activation for VF was predictive of naming decline in left TLE after ATLR.     

Interictal language functions in temporal lobe epilepsy

OBJECTIVE: To evaluate interictal language functions in patients with medically intractable left and right sided mesial temporal lobe epilepsy (TLE). METHODS: Spontaneous speech, language comprehension, confrontation naming, repetition, reading, writing, and word fluency were examined in 12 patients with left sided TLE and 11 patients with right sided TLE. RESULTS: Four patients out of 23 displayed language deficits in more than one language domain. Three further patients exhibited isolated language deficits. Linguistic deficits were observed in both left TLE and right TLE. In quantitative analyses left and right TLE only differed in spontaneous speech (p = 0.02); no difference was found in other language functions, laterality quotient of Wada test, or overall IQ. Qualitative error analysis of object naming, however, showed typical errors associated only with left TLE. Patients with linguistic deficits were older at testing compared to patients without linguistic deficits (p = 0.003), whereas other factors including side of TLE, handedness, educational level, age at epilepsy onset, and duration of epilepsy did not differ between groups. CONCLUSIONS: Possible explanations for these findings include neuronal cell loss and deafferentiation in cortical areas, and disruption of the basal temporal language area pathways. Our study suggests that some patients with chronic mesial TLE exhibit linguistic deficits when specifically tested, and underlines the need to routinely investigate linguistic functions in TLE.     

Comprehension and production of nouns and verbs in temporal lobe epilepsy

Previous research on linguistic performance at the single-word level in patients with temporal lobe epilepsy (TLE) has mostly been limited to the comprehension and production of nouns, and findings have been inconsistent. Results are likewise limited and controversial regarding the lateralization of the epileptogenic focus. The present study investigates comprehension and production of nouns and verbs in patients with left and right TLE (12 in each group). We designed a comprehension (word-picture matching) test and a production (naming) test, matched on a range of psycholinguistic parameters for the two word classes. The results showed impaired verb comprehension in patients with left TLE and impaired noun and verb production in both groups of patients compared to the control group. Patients with left and right TLE differed significantly on verb comprehension and noun production, whereas verb production was equally impaired in the two groups of patients. These findings suggest difficulties with single-word processing in patients with both left and right TLE, which are more prominent for verbs than for nouns in patients with left TLE. The verb production (action naming) test turned out to be the most effective tool for assessing linguistic difficulties at the single-word level in patients with TLE.     

Ipsilateral Reorganization of Language in Early-Onset Left Temporal Lobe Epilepsy

Purpose. Decline in confrontation naming ability occurs in a subset of temporal lobe epilepsy (TLE) patients following left (dominant) anterior temporal lobectomy (ATL). Patients with late age of onset of seizures are most vulnerable to such decline. In addition, object names typically acquired later in language development are the words most likely to be inaccessible after ATL. Early-onset left TLE patients may be at lower risk for post-ATL dysnomia either because they have a limited preoperative lexicon that does not include most late-age-of-acquistion names or they undergo early ipsilateral language reorganization, which results in a lexicon similar to that of late-onset TLE patients but offers protection from post-ATL naming decline.Methods. Sixty-five left hemisphere speech dominant left TLE patients who had undergone ATL were assessed pre- and postoperatively on the Boston Naming Test (BNT).Results. The early- and late-onset groups performed similarly across three BNT age-of-acquisition categories at the preoperative assessment. Words acquired relatively later in life were most likely to become inaccessible postoperatively for both groups, but the early-onset patients showed significantly less overall postoperative decline in naming ability compared with the late-onset group.Conclusions. The more stable pre- to postoperative naming performance exhibited by early-onset patients cannot be attributed to lack of acquisition of the words shown to be most vulnerable to postoperative decline (i.e., late-age-of-acquisition words). Their object naming stability suggests that early-onset left TLE patients undergo intrahemispheric reorganization of language early in life that provides protective benefits.     

Auditory and visual naming tests: normative and patient data for accuracy, response time, and tip-of-the-tongue.

Naming is typically assessed with visual naming tasks, yet, some patients with genuine word-finding difficulty (evident in auditorily based discourse) show minimal difficulty on such measures. Evidence from cortical mapping, brain imaging and neuropsychological studies suggests that auditory naming measures might provide more relevant or at least, complementary information. We developed comparable auditory and visual naming tests and present normative data for accuracy, response time, and tip-of-the-tongue responses based on 100 controls. Test validity was supported by findings that left temporal lobe epilepsy (TLE) patients (i.e., a population with expected naming difficulty) performed more poorly on auditory but not visual naming compared to right TLE patients (i.e., a population without expected naming difficulty). Internal and test-retest reliability coefficients were reasonable. Finally, test utility was assessed on an individual basis, and auditory but not visual naming performance predicted impairment.     

Memory functions following surgery for temporal lobe epilepsy in children

Surgical treatment appears to improve the cognitive prognosis in children undergoing surgery for temporal lobe epilepsy (TLE). The beneficial effects of surgery on memory functions, particularly on material-specific memory, are more difficult to assess because of potentially interacting factors such as age range, intellectual level, left-handedness, type of surgery and seizure outcome. This study investigated memory functions in 20 right-handed children who had left or right-temporal lobe surgery - including hippocampectomy - and became seizure-free. The neuropsychological evaluation included tests measuring verbally and visually mediated episodic memory, everyday memory as well as attention/working memory and language/semantic memory. We also assessed the relationships between age of seizure onset, general cognitive ability and memory functions. Children with TLE showed poor memory efficiency before surgery that tended to improve about 1 year after surgery. We found a material-specific memory effect, especially after surgery-9 (out of 12) children with left TLE had worse verbal memory results while 5 (out of 8) with right TLE had worse visual memory results. Post-operatively, most children had poor everyday memory performance on the Rivermead Behavioural Memory Test. No significant relationship was observed between episodic memory scores and age of epilepsy onset but children with early onset remained with lower Performance IQ values, Rey's figure copy scores and naming performances after surgery. Surgery significantly improved all the attention/working memory scores, some verbal episodic memory tasks and naming test performances. A different pattern of episodic and semantic memory limitations related to left or right TLE was observed.     

Adequacy of language function and verbal memory performance in unilateral temporal lobe epilepsy.

We examined adequacy of language functions, their influence on verbal learning and memory performance, and the relative effects of language function and laterality of seizure focus on the memory performance of 99 left-hemisphere dominant patients with invasively verified epilepsy of left (N = 47) or right (N = 52) temporal lobe origin. Patients with left temporal lobe epilepsy (TLE) scored significantly lower than the right TLE group on several aphasia battery subtests (Visual Naming, Sentence Repetition, Token Test, Reading Comprehension, Aural Comprehension). Adequacy of language function (nominal speech) was significantly related to verbal learning and memory performance for both left and right TLE groups. Finally, comparison of the predictive significance of laterality of TLE and adequacy of language function indicated that language functions (Visual Naming and Aural Comprehension), but not laterality of TLE, were significant predictors for verbal learning and memory performance. It is concluded that: 1) adequacy of basic language functions is particularly compromised in left TLE, 2) there is a significant relationship between adequacy of language function and several aspects of verbal learning and memory ability in both left and right temporal lobe groups, and 3) clinical assessment and theoretical models of memory need to consider these relationships.     

Utility of the Boston naming test in predicting ultimate side of surgery in patients with medically intractable temporal lobe epilepsy

PURPOSE: Confrontation naming tasks have long been presumed to be sensitive to left temporal dysfunction and, consequently, are frequently used in the evaluation of surgical epilepsy patients. Despite wide and frequent use, few studies have examined the utility of confrontation naming tasks in individuals with temporal lobe epilepsy (TLE). METHODS: The current study examined the presurgical Boston Naming Test (BNT) performance of 217 right-handed adult patients with intractable TLE (left, 108; right, 109) to determine the utility of this measure in predicting ultimate side of surgery. RESULTS: The results support the clinical utility of the BNT in determining ultimate side of surgery and suggest that the BNT has incremental validity over and above presurgical delayed memory and intelligence scores. This relation was found to be moderated by Full Scale IQ (FSIQ), age at seizure onset, and duration of epilepsy. The use of a logistic regression equation to predict side of surgery revealed that prediction of left temporal surgery was best among patients with low BNT scores, high FSIQs, and late age at seizure onset. In contrast, right temporal surgery was best predicted among patients with high BNT scores, low FSIQs, and short duration of epilepsy. CONCLUSIONS: This study supports the clinical utility of the BNT in the preoperative evaluation of candidates for TLE surgery and highlights the importance of examining potential moderating variables when making predictions about side of surgery. This study further provides clinicians with a regression equation that can be used to predict side of surgery in patients with temporal lobe epilepsy.     

Neural correlates of verbal semantic memory in patients with temporal lobe epilepsy

Functional imaging data suggest that the core network engaged in verbal semantic memory (SM) processing encompasses frontal and temporal lobe structures, with a strong left lateralization in normal right handers. The impact of long term temporal lobe epilepsy (TLE) on this network has only partly been elucidated. We studied verbal SM in 50 patients with chronic, intractable TLE (left TLE=26, right TLE=24) and 35 right handed normal controls using a verbal fMRI semantic decision paradigm. All patients had language lateralized to the left hemisphere, as verified by the intracarotid amobarbital procedure. Within and between group analyses showed remarkable, group-specific activation profiles. The control group activated frontal and temporal areas bilaterally, with a strong left predominance. Left TLE patients showed a shift of activations of left frontal and medial temporal areas to homologous regions in the right hemisphere. Furthermore, left TLE subjects utilized subcortical structures such as the thalamus and putamen to accomplish the verbal SM task. Contrastively, the activation pattern of right TLE patients resembled that of normal controls, but exhibited "hypofrontality" with a shift from frontal to posterior regions in the temporal, parietal and occipital lobe. Our results show that chronic epileptic activity originating from temporal seizure foci is associated with an alteration of neural circuits which support semantic language processing and that side of seizure focus has a specific impact on the resulting activation network. These findings presumably result from morphological changes and from functional reorganization which are both inherent to chronic TLE.     

Relation of sorting impairment to hippocampal damage in temporal lobe epilepsy

One hundred and twelve patients with left (n=65) or right (n=47) temporal lobe epilepsy (TLE), associated with mesial or lateral temporal lobe lesion, were compared to 53 patients with left (n=30) or right (n=23) frontal lobe epilepsy (FLE), in order to explore the contributions of hippocampal lesions and of memory deficits to sorting impairment. Thirty-six healthy subjects of similar age and education were controls. The Modified Wisconsin Card Sorting Test (MWCST) was used to explore sorting ability. The two-syllable word span and consistent long-term retrieval from the selective reminding procedure for word-list learning were used to evaluate memory. Raven's Coloured Progressive Matrices and Attentive Matrices served to control for abstract reasoning and attention. Left FLE patients and TLE patients with left hippocampal sclerosis were significantly impaired on MWCST, short-term memory, and word learning. TLE patients with other left hippocampal lesions were also impaired on MWCST, although not significantly so. Analysis of individual scores showed that 42% of TLE patients with left hippocampal sclerosis, 14% of TLE patients with other hippocampal lesions, 63% of left FLE patients, and 30% of right FLE patients were impaired on the MWCST. In patients with left hippocampal sclerosis, MWCST score was associated with the learning score provided by the selective reminding procedure and Raven's Coloured Progressive Matrices score, whereas in FLE patients, MWCST score was associated with Attentive Matrices score. These results suggest that only some TLE patients, i.e. those with hippocampal damage, may be expected to be impaired on card sorting. The impaired sorting ability of these TLE patients may be due to involvement of the hippocampal function in forming associations or in registering new information.     

Naming outcomes of anterior temporal lobectomy in epilepsy patients: a systematic review of the literature

Anterior temporal lobectomy (ATL) is the standard surgical treatment for medically intractable temporal lobe epilepsy (TLE). While seizure outcome is favorable, cognitive outcomes are a concern, particularly in respect of memory and naming. A systematic review of the literature on the naming outcomes of ATL is presented in this article. Searches were conducted on PubMed and PsycInfo, yielding a total of 93 articles, 21 of which met inclusion criteria. Declines in visual naming are common following ATL in the dominant hemisphere, and particularly, for naming living stimuli or famous faces. The Boston Naming Test (BNT) declines by a mean of 5.8 points, exceeding the Reliable Change Index (RCI). There are no reports of deficits in auditory naming following ATL, despite the fact that auditory naming has shown to be a more sensitive measure of dysnomia than the BNT in TLE patients. The absence of structural hippocampal pathology and late-onset epilepsy are the strongest predictors of naming decline. Recommendations are made for further study.