ObjectiveStereoelectroencephalography (SEEG)‐guided radiofrequency ablation (RFA) is increasingly... more ObjectiveStereoelectroencephalography (SEEG)‐guided radiofrequency ablation (RFA) is increasingly being used as a treatment for drug‐resistant localization‐related epilepsy. The aim of this study is to analyze the successes and failures using RFA and how response correlates with surgical epilepsy treatment outcomes.MethodsWe retrospectively reviewed 62 patients who underwent RFA via SEEG electrodes. After excluding five, the remaining 57 were classified into subgroups based on procedures and outcomes. Forty patients (70%) underwent a secondary surgical procedure, of whom 32 were delayed: 26 laser interstitial thermal therapy (LITT), five resection, one neuromodulation. We determined the predictive value of RFA outcome upon subsequent surgical outcome by categorizing the delayed secondary surgery outcome as success (Engel I/II) versus failure (Engel III/IV). Demographic information, epilepsy characteristics, and the transient time of seizure freedom after RFA were calculated for each...
Non‐conscious processing of human memory has traditionally been difficult to objectively measure ... more Non‐conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event‐related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal‐dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = 54), applying new controls for construct validity, and developing an improved, open‐source tool for automated analysis of the procedure used for equating levels of memory awareness. Results faithfully reproduced prior ERP findings of parietal effects that a series of systematic control analyses validated were not contributed to nor contaminated by explicit memory...
ObjectiveMedial temporal lobe epilepsy (TLE) is the most common form of medication‐resistant foca... more ObjectiveMedial temporal lobe epilepsy (TLE) is the most common form of medication‐resistant focal epilepsy in adults. Despite removal of medial temporal structures, more than one‐third of patients continue to have disabling seizures postoperatively. Seizure refractoriness implies that extramedial regions are capable of influencing the brain network and generating seizures. We tested whether abnormalities of structural network integration could be associated with surgical outcomes.MethodsPresurgical magnetic resonance images from 121 patients with drug‐resistant TLE across 3 independent epilepsy centers were used to train feed‐forward neural network models based on tissue volume or graph‐theory measures from whole‐brain diffusion tensor imaging structural connectomes. An independent dataset of 47 patients with TLE from 3 other epilepsy centers was used to assess the predictive values of each model and regional anatomical contributions toward surgical treatment results.ResultsThe rec...
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Jan 28, 2018
The NIH Cognitive Toolbox Picture Sequence Memory Test (PSMT) was developed as a measure of learn... more The NIH Cognitive Toolbox Picture Sequence Memory Test (PSMT) was developed as a measure of learning ability. PSMT use in clinical populations is only beginning to be investigated. PSMT performance was analyzed in a retrospective series of 221 patients referred to either the Deep Brain Stimulation Clinic (n = 128) for presurgical evaluation, or to the Cognitive Screening Clinic (n = 93). Patients were also administered the Rey Verbal Auditory Verbal Learning test (AVLT). In addition to correlation between measures, classification agreement was examined based upon performance ratings of normal (>16th percentile), borderline (5-16th percentile), or impaired (<5th percentile). Correlation between measures was significant (r = 0.48, p < .0001), with classification agreement of 62% (weighted Kappa = 0.43). For patients with valid PVT scores (n = 147), correlation between tests was 0.67 (p < .0001) with a classification agreement of 72% (weighted Kappa = 0.44). Multiple level ...
To evaluate the outcomes one-year and longer following stereotactic laser amygdalohippocampotomy ... more To evaluate the outcomes one-year and longer following stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy in a large series of patients treated over a five-year period since introduction of this novel technique. Surgical outcomes of a consecutive series of fifty-eight patients with mesial temporal lobe epilepsy who underwent the surgery at our institution with at least 12-months follow-up were retrospectively evaluated. A subgroup analysis was performed comparing patients with and without mesial temporal sclerosis. One-year following stereotactic laser amygdalohippocampotomy 53.4% (95% confidence interval: 40.8%-65.7%) of all patients were free of disabling seizures (Engel 1). Three of nine patients became seizure free following repeat ablation. Subgroup analysis showed that 60.5% (95% confidence interval: 45.6%-73.7%) of patients with mesial temporal sclerosis were free of disabling seizures as compared to 33.3% (95% confidence interval: 15.0%-58.5%) of pat...
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Jan 15, 2016
The objective is to examine failure on three embedded performance validity tests [Reliable Digit ... more The objective is to examine failure on three embedded performance validity tests [Reliable Digit Span (RDS), Auditory Verbal Learning Test (AVLT) logistic regression, and AVLT recognition memory] in early Alzheimer disease (AD;n= 178), amnestic mild cognitive impairment (MCI;n= 365), and cognitively intact age-matched controls (n= 206). Neuropsychological tests scores were obtained from subjects participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI). RDS failure using a ≤7 RDS threshold was 60/178 (34%) for early AD, 52/365 (14%) for MCI, and 17/206 (8%) for controls. A ≤6 RDS criterion reduced this rate to 24/178 (13%) for early AD, 15/365 (4%) for MCI, and 7/206 (3%) for controls. AVLT logistic regression probability of ≥.76 yielded unacceptably high false-positive rates in both clinical groups [early AD = 149/178 (79%); MCI = 159/365 (44%)] but not cognitively intact controls (13/206, 6%). AVLT recognition criterion of ≤9/15 classified 125/178 (70%) of early ...
Both animal research and human research suggest that interictal epileptiform discharges (IEDs) ma... more Both animal research and human research suggest that interictal epileptiform discharges (IEDs) may affect cognition, although the significance of such findings remains controversial. We review a wide range of literature with bearing on this topic and present relevant epilepsy surgery cases, which suggest that the effects of IEDs may be substantial and informative for surgical planning. In the first case, we present a patient with epilepsy with left anterior temporal lobe (TL) seizure onset who experienced frequent IEDs during preoperative neuropsychological assessment. Cognitive results strongly lateralized to the left TL. Because the patient failed performance validity tests and appeared amnestic for verbal materials inconsistent with his work history, selected neuropsychological tests were repeated 6weeks later. Scores improved one to two standard deviations over the initial evaluation and because of this improvement, were only mildly suggestive of left TL impairment. The second c...
Stereotactic laser amygdalohippocampotomy (SLAH) uses laser interstitial thermal therapy guided b... more Stereotactic laser amygdalohippocampotomy (SLAH) uses laser interstitial thermal therapy guided by magnetic resonance thermography. This novel intervention can achieve seizure freedom while minimizing collateral damage compared to traditional open surgery, in patients with mesial temporal lobe epilepsy. An algorithm is presented to guide treatment decisions for initial and repeat procedures in patients with and without mesial temporal sclerosis. SLAH may improve access by medication-refractory patients to effective surgical treatments and thereby decrease medical complications, increase productivity, and minimize socioeconomic consequences in patients with chronic epilepsy.
We examined whether individual neuronal architecture obtained from the brain connectome can be us... more We examined whether individual neuronal architecture obtained from the brain connectome can be used to estimate the surgical success of anterior temporal lobectomy (ATL) in patients with temporal lobe epilepsy (TLE). We retrospectively studied 35 consecutive patients with TLE who underwent ATL. The structural brain connectome was reconstructed from all patients using presurgical diffusion MRI. Network links in patients were standardized as Z scores based on connectomes reconstructed from healthy controls. The topography of abnormalities in linkwise elements of the connectome was assessed on subnetworks linking ipsilateral temporal with extratemporal regions. Predictive models were constructed based on the individual prevalence of linkwise Z scores >2 and based on presurgical clinical data. Patients were more likely to achieve postsurgical seizure freedom if they exhibited fewer abnormalities within a subnetwork composed of the ipsilateral hippocampus, amygdala, thalamus, superior...
Neuropsychiatry, neuropsychology, and behavioral neurology, 2002
The Trail Making Test (TMT) is a psychomotor task that is used routinely in clinical evaluations ... more The Trail Making Test (TMT) is a psychomotor task that is used routinely in clinical evaluations and consists of two parts: TMT-A and TMT-B. The purpose of the present study was to examine the relations of two derived-TMT indices with age, education, and gender and to establish normative data. Prior research has suggested that these derived indices provide purer measures of the executive skills required to complete TMT-B. It has also been suggested that these scores can be effectively used to detect cognitive impairment, and that they are relatively free from the impact of age. Difference scores (B minus sign A) and ratio scores (B:A) were computed from the TMT performance of 285 adults who have no history of substance abuse or psychiatric or neurologic disorder and who are not currently being treated with any type of psychotropic medication. Subjects ranged in age from 18 to 90 years and in education level from 6 to 20 years. For the entire sample, (B minus sign A) scores ranged fr...
SummaryObjectivesPatients with temporal lobe epilepsy (TLE) experience significant deficits in ca... more SummaryObjectivesPatients with temporal lobe epilepsy (TLE) experience significant deficits in category‐related object recognition and naming following standard surgical approaches. These deficits may result from a decoupling of core processing modules (e.g., language, visual processing, and semantic memory), due to “collateral damage” to temporal regions outside the hippocampus following open surgical approaches. We predicted that stereotactic laser amygdalohippocampotomy (SLAH) would minimize such deficits because it preserves white matter pathways and neocortical regions that are critical for these cognitive processes.MethodsTests of naming and recognition of common nouns (Boston Naming Test) and famous persons were compared with nonparametric analyses using exact tests between a group of 19 patients with medically intractable mesial TLE undergoing SLAH (10 dominant, 9 nondominant), and a comparable series of TLE patients undergoing standard surgical approaches (n = 39) using a p...
Objective-Based upon Damasio's "Convergence Zone" model of semantic memory, we predicted that epi... more Objective-Based upon Damasio's "Convergence Zone" model of semantic memory, we predicted that epilepsy surgical patients with anterior temporal lobe (TL) seizure onset would exhibit a pattern of category-specific naming and recognition deficits not observed in patients with seizures arising elsewhere. Methods-We assessed epilepsy patients with unilateral seizure onset of anterior TL or other origin (n = 22), pre-or postoperatively, using a set of category-specific items and a conventional measure of visual naming (Boston Naming Test: BNT). Results-Category-specific naming deficits were exhibited by patients with dominant anterior TL seizure onset/resection for famous faces and animals, while category-specific recognition deficits for these same categories were exhibited by patients with nondominant anterior TL onset/resection. Patients with other seizure onset did not exhibit category-specific deficits. Naming and recognition deficits were frequently not detected by the BNT, which samples only a limited range of stimuli. Interpretation-Consistent with the "convergence zone" framework, results suggest that the nondominant anterior TL plays a major role in binding sensory information into conceptual percepts for certain stimuli, while dominant TL regions function to provide a link to verbal labels for these percepts. Although observed category-specific deficits were striking, they were often missed by the BNT, suggesting that they are more prevalent than recognized in both pre-and postsurgical epilepsy patients. Systematic investigation of these deficits could lead to more refined models of semantic memory, aid in the localization of seizures, and contribute to modifications in surgical technique and patient selection in epilepsy surgery to improve neurocognitive outcome.
Long-term video-EEG monitoring (LTM) is the gold standard for initial lateralization and localiza... more Long-term video-EEG monitoring (LTM) is the gold standard for initial lateralization and localization of seizures in the workup for neurosurgical treatment of medically intractable epilepsy. Previous studies have yielded contradictory results as to whether seizures that occur in clusters tend to arise from the same brain region and may lead to the incorrect conclusion that seizures arise from a single focus. To determine whether seizure clustering affects localization in an LTM setting, the authors performed an observational study over 6 years at a large regional epilepsy center on those undergoing LTM for seizure diagnosis, characterization, or presurgical workup. Excluding repeat studies and LTMs with generalized or nonepileptic seizures resulted in 479 monitorings with 2774 focal seizures for analysis. Sequential pairs of consecutive focal seizures were classed as ''concordant'', ''discordant,'' or ''other,'' based on EEG localization. ANOVA analysis on the logarithm of the interseizure interval (LISI) among the three seizure pair groups showed no significant difference, p = 0.47, nor did analysis defining concordance as lateralization to the same hemisphere (p = 0.34). Analyses on subgroups with multifocal seizures, bilateral seizures, and extratemporal seizures all failed to show a significant difference. In conclusion, seizures have the same localizing value whether occurring in a cluster over a few hours or sporadically over a few days. This could potentially lead to shorter monitoring times.
Patients with frontal lobe dysfunction (e.g., Huntington's Disease) reportedly benefit more from ... more Patients with frontal lobe dysfunction (e.g., Huntington's Disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer's disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task while patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset as determined by video-EEG monitoring on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age of seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. FL patients performed significantly worse than TL patients on the standard semantic fluency paradigm (TL M = 18.4, SD = 4.7; FL M = 11.1, SD = 5.3), t (27) = −3.75, p < .001. Nevertheless, results of an ANCOVA demonstrated that the FL patients showed significantly greater performance improvement than the TL patients when provided with a cued semantic fluency format even after controlling for baseline differences in ability on the standard semantic fluency task (TL M = 0.45, SD = 3.8; FL M = 9.4, SD = 5.1), F (1, 29) = 12.37, p = .002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction
We present a patient with right-hemispheric speech lateralization who exhibited severe recognitio... more We present a patient with right-hemispheric speech lateralization who exhibited severe recognition and naming deficits for unique objects (famous faces and landmarks) and grossly normal recognition and naming performances for nonunique objects (animals and man-made objects) following an anterior right temporal lobe (TL) resection of a ganglioglioma. While recognition deficits have been reported for famous faces following right temporal pole lesions, and for landmarks and geographic regions following right TL damage in general, this is the first reported case of both recognition and naming deficits for these objects resulting from a single lesion. These results are consistent with research suggesting that the neuroanatomic substrates for the recognition and naming of unique objects lie in the anterior TL regions. Left temporal pole lesions have been associated with naming deficits for unique objects while right temporal pole lesions have been associated with recognition deficits for unique objects. However, these findings suggest that the substrates of naming can be located in homotopic regions of the right hemisphere when language lateralization is atypical. As various object categories appear to have different neuroanatomical representations in the TLs, we discuss the possible benefits of sampling a wider array of objects during cortical stimulation mapping of language.
ObjectiveStereoelectroencephalography (SEEG)‐guided radiofrequency ablation (RFA) is increasingly... more ObjectiveStereoelectroencephalography (SEEG)‐guided radiofrequency ablation (RFA) is increasingly being used as a treatment for drug‐resistant localization‐related epilepsy. The aim of this study is to analyze the successes and failures using RFA and how response correlates with surgical epilepsy treatment outcomes.MethodsWe retrospectively reviewed 62 patients who underwent RFA via SEEG electrodes. After excluding five, the remaining 57 were classified into subgroups based on procedures and outcomes. Forty patients (70%) underwent a secondary surgical procedure, of whom 32 were delayed: 26 laser interstitial thermal therapy (LITT), five resection, one neuromodulation. We determined the predictive value of RFA outcome upon subsequent surgical outcome by categorizing the delayed secondary surgery outcome as success (Engel I/II) versus failure (Engel III/IV). Demographic information, epilepsy characteristics, and the transient time of seizure freedom after RFA were calculated for each...
Non‐conscious processing of human memory has traditionally been difficult to objectively measure ... more Non‐conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event‐related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal‐dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = 54), applying new controls for construct validity, and developing an improved, open‐source tool for automated analysis of the procedure used for equating levels of memory awareness. Results faithfully reproduced prior ERP findings of parietal effects that a series of systematic control analyses validated were not contributed to nor contaminated by explicit memory...
ObjectiveMedial temporal lobe epilepsy (TLE) is the most common form of medication‐resistant foca... more ObjectiveMedial temporal lobe epilepsy (TLE) is the most common form of medication‐resistant focal epilepsy in adults. Despite removal of medial temporal structures, more than one‐third of patients continue to have disabling seizures postoperatively. Seizure refractoriness implies that extramedial regions are capable of influencing the brain network and generating seizures. We tested whether abnormalities of structural network integration could be associated with surgical outcomes.MethodsPresurgical magnetic resonance images from 121 patients with drug‐resistant TLE across 3 independent epilepsy centers were used to train feed‐forward neural network models based on tissue volume or graph‐theory measures from whole‐brain diffusion tensor imaging structural connectomes. An independent dataset of 47 patients with TLE from 3 other epilepsy centers was used to assess the predictive values of each model and regional anatomical contributions toward surgical treatment results.ResultsThe rec...
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Jan 28, 2018
The NIH Cognitive Toolbox Picture Sequence Memory Test (PSMT) was developed as a measure of learn... more The NIH Cognitive Toolbox Picture Sequence Memory Test (PSMT) was developed as a measure of learning ability. PSMT use in clinical populations is only beginning to be investigated. PSMT performance was analyzed in a retrospective series of 221 patients referred to either the Deep Brain Stimulation Clinic (n = 128) for presurgical evaluation, or to the Cognitive Screening Clinic (n = 93). Patients were also administered the Rey Verbal Auditory Verbal Learning test (AVLT). In addition to correlation between measures, classification agreement was examined based upon performance ratings of normal (>16th percentile), borderline (5-16th percentile), or impaired (<5th percentile). Correlation between measures was significant (r = 0.48, p < .0001), with classification agreement of 62% (weighted Kappa = 0.43). For patients with valid PVT scores (n = 147), correlation between tests was 0.67 (p < .0001) with a classification agreement of 72% (weighted Kappa = 0.44). Multiple level ...
To evaluate the outcomes one-year and longer following stereotactic laser amygdalohippocampotomy ... more To evaluate the outcomes one-year and longer following stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy in a large series of patients treated over a five-year period since introduction of this novel technique. Surgical outcomes of a consecutive series of fifty-eight patients with mesial temporal lobe epilepsy who underwent the surgery at our institution with at least 12-months follow-up were retrospectively evaluated. A subgroup analysis was performed comparing patients with and without mesial temporal sclerosis. One-year following stereotactic laser amygdalohippocampotomy 53.4% (95% confidence interval: 40.8%-65.7%) of all patients were free of disabling seizures (Engel 1). Three of nine patients became seizure free following repeat ablation. Subgroup analysis showed that 60.5% (95% confidence interval: 45.6%-73.7%) of patients with mesial temporal sclerosis were free of disabling seizures as compared to 33.3% (95% confidence interval: 15.0%-58.5%) of pat...
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Jan 15, 2016
The objective is to examine failure on three embedded performance validity tests [Reliable Digit ... more The objective is to examine failure on three embedded performance validity tests [Reliable Digit Span (RDS), Auditory Verbal Learning Test (AVLT) logistic regression, and AVLT recognition memory] in early Alzheimer disease (AD;n= 178), amnestic mild cognitive impairment (MCI;n= 365), and cognitively intact age-matched controls (n= 206). Neuropsychological tests scores were obtained from subjects participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI). RDS failure using a ≤7 RDS threshold was 60/178 (34%) for early AD, 52/365 (14%) for MCI, and 17/206 (8%) for controls. A ≤6 RDS criterion reduced this rate to 24/178 (13%) for early AD, 15/365 (4%) for MCI, and 7/206 (3%) for controls. AVLT logistic regression probability of ≥.76 yielded unacceptably high false-positive rates in both clinical groups [early AD = 149/178 (79%); MCI = 159/365 (44%)] but not cognitively intact controls (13/206, 6%). AVLT recognition criterion of ≤9/15 classified 125/178 (70%) of early ...
Both animal research and human research suggest that interictal epileptiform discharges (IEDs) ma... more Both animal research and human research suggest that interictal epileptiform discharges (IEDs) may affect cognition, although the significance of such findings remains controversial. We review a wide range of literature with bearing on this topic and present relevant epilepsy surgery cases, which suggest that the effects of IEDs may be substantial and informative for surgical planning. In the first case, we present a patient with epilepsy with left anterior temporal lobe (TL) seizure onset who experienced frequent IEDs during preoperative neuropsychological assessment. Cognitive results strongly lateralized to the left TL. Because the patient failed performance validity tests and appeared amnestic for verbal materials inconsistent with his work history, selected neuropsychological tests were repeated 6weeks later. Scores improved one to two standard deviations over the initial evaluation and because of this improvement, were only mildly suggestive of left TL impairment. The second c...
Stereotactic laser amygdalohippocampotomy (SLAH) uses laser interstitial thermal therapy guided b... more Stereotactic laser amygdalohippocampotomy (SLAH) uses laser interstitial thermal therapy guided by magnetic resonance thermography. This novel intervention can achieve seizure freedom while minimizing collateral damage compared to traditional open surgery, in patients with mesial temporal lobe epilepsy. An algorithm is presented to guide treatment decisions for initial and repeat procedures in patients with and without mesial temporal sclerosis. SLAH may improve access by medication-refractory patients to effective surgical treatments and thereby decrease medical complications, increase productivity, and minimize socioeconomic consequences in patients with chronic epilepsy.
We examined whether individual neuronal architecture obtained from the brain connectome can be us... more We examined whether individual neuronal architecture obtained from the brain connectome can be used to estimate the surgical success of anterior temporal lobectomy (ATL) in patients with temporal lobe epilepsy (TLE). We retrospectively studied 35 consecutive patients with TLE who underwent ATL. The structural brain connectome was reconstructed from all patients using presurgical diffusion MRI. Network links in patients were standardized as Z scores based on connectomes reconstructed from healthy controls. The topography of abnormalities in linkwise elements of the connectome was assessed on subnetworks linking ipsilateral temporal with extratemporal regions. Predictive models were constructed based on the individual prevalence of linkwise Z scores >2 and based on presurgical clinical data. Patients were more likely to achieve postsurgical seizure freedom if they exhibited fewer abnormalities within a subnetwork composed of the ipsilateral hippocampus, amygdala, thalamus, superior...
Neuropsychiatry, neuropsychology, and behavioral neurology, 2002
The Trail Making Test (TMT) is a psychomotor task that is used routinely in clinical evaluations ... more The Trail Making Test (TMT) is a psychomotor task that is used routinely in clinical evaluations and consists of two parts: TMT-A and TMT-B. The purpose of the present study was to examine the relations of two derived-TMT indices with age, education, and gender and to establish normative data. Prior research has suggested that these derived indices provide purer measures of the executive skills required to complete TMT-B. It has also been suggested that these scores can be effectively used to detect cognitive impairment, and that they are relatively free from the impact of age. Difference scores (B minus sign A) and ratio scores (B:A) were computed from the TMT performance of 285 adults who have no history of substance abuse or psychiatric or neurologic disorder and who are not currently being treated with any type of psychotropic medication. Subjects ranged in age from 18 to 90 years and in education level from 6 to 20 years. For the entire sample, (B minus sign A) scores ranged fr...
SummaryObjectivesPatients with temporal lobe epilepsy (TLE) experience significant deficits in ca... more SummaryObjectivesPatients with temporal lobe epilepsy (TLE) experience significant deficits in category‐related object recognition and naming following standard surgical approaches. These deficits may result from a decoupling of core processing modules (e.g., language, visual processing, and semantic memory), due to “collateral damage” to temporal regions outside the hippocampus following open surgical approaches. We predicted that stereotactic laser amygdalohippocampotomy (SLAH) would minimize such deficits because it preserves white matter pathways and neocortical regions that are critical for these cognitive processes.MethodsTests of naming and recognition of common nouns (Boston Naming Test) and famous persons were compared with nonparametric analyses using exact tests between a group of 19 patients with medically intractable mesial TLE undergoing SLAH (10 dominant, 9 nondominant), and a comparable series of TLE patients undergoing standard surgical approaches (n = 39) using a p...
Objective-Based upon Damasio's "Convergence Zone" model of semantic memory, we predicted that epi... more Objective-Based upon Damasio's "Convergence Zone" model of semantic memory, we predicted that epilepsy surgical patients with anterior temporal lobe (TL) seizure onset would exhibit a pattern of category-specific naming and recognition deficits not observed in patients with seizures arising elsewhere. Methods-We assessed epilepsy patients with unilateral seizure onset of anterior TL or other origin (n = 22), pre-or postoperatively, using a set of category-specific items and a conventional measure of visual naming (Boston Naming Test: BNT). Results-Category-specific naming deficits were exhibited by patients with dominant anterior TL seizure onset/resection for famous faces and animals, while category-specific recognition deficits for these same categories were exhibited by patients with nondominant anterior TL onset/resection. Patients with other seizure onset did not exhibit category-specific deficits. Naming and recognition deficits were frequently not detected by the BNT, which samples only a limited range of stimuli. Interpretation-Consistent with the "convergence zone" framework, results suggest that the nondominant anterior TL plays a major role in binding sensory information into conceptual percepts for certain stimuli, while dominant TL regions function to provide a link to verbal labels for these percepts. Although observed category-specific deficits were striking, they were often missed by the BNT, suggesting that they are more prevalent than recognized in both pre-and postsurgical epilepsy patients. Systematic investigation of these deficits could lead to more refined models of semantic memory, aid in the localization of seizures, and contribute to modifications in surgical technique and patient selection in epilepsy surgery to improve neurocognitive outcome.
Long-term video-EEG monitoring (LTM) is the gold standard for initial lateralization and localiza... more Long-term video-EEG monitoring (LTM) is the gold standard for initial lateralization and localization of seizures in the workup for neurosurgical treatment of medically intractable epilepsy. Previous studies have yielded contradictory results as to whether seizures that occur in clusters tend to arise from the same brain region and may lead to the incorrect conclusion that seizures arise from a single focus. To determine whether seizure clustering affects localization in an LTM setting, the authors performed an observational study over 6 years at a large regional epilepsy center on those undergoing LTM for seizure diagnosis, characterization, or presurgical workup. Excluding repeat studies and LTMs with generalized or nonepileptic seizures resulted in 479 monitorings with 2774 focal seizures for analysis. Sequential pairs of consecutive focal seizures were classed as ''concordant'', ''discordant,'' or ''other,'' based on EEG localization. ANOVA analysis on the logarithm of the interseizure interval (LISI) among the three seizure pair groups showed no significant difference, p = 0.47, nor did analysis defining concordance as lateralization to the same hemisphere (p = 0.34). Analyses on subgroups with multifocal seizures, bilateral seizures, and extratemporal seizures all failed to show a significant difference. In conclusion, seizures have the same localizing value whether occurring in a cluster over a few hours or sporadically over a few days. This could potentially lead to shorter monitoring times.
Patients with frontal lobe dysfunction (e.g., Huntington's Disease) reportedly benefit more from ... more Patients with frontal lobe dysfunction (e.g., Huntington's Disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer's disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task while patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset as determined by video-EEG monitoring on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age of seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. FL patients performed significantly worse than TL patients on the standard semantic fluency paradigm (TL M = 18.4, SD = 4.7; FL M = 11.1, SD = 5.3), t (27) = −3.75, p < .001. Nevertheless, results of an ANCOVA demonstrated that the FL patients showed significantly greater performance improvement than the TL patients when provided with a cued semantic fluency format even after controlling for baseline differences in ability on the standard semantic fluency task (TL M = 0.45, SD = 3.8; FL M = 9.4, SD = 5.1), F (1, 29) = 12.37, p = .002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction
We present a patient with right-hemispheric speech lateralization who exhibited severe recognitio... more We present a patient with right-hemispheric speech lateralization who exhibited severe recognition and naming deficits for unique objects (famous faces and landmarks) and grossly normal recognition and naming performances for nonunique objects (animals and man-made objects) following an anterior right temporal lobe (TL) resection of a ganglioglioma. While recognition deficits have been reported for famous faces following right temporal pole lesions, and for landmarks and geographic regions following right TL damage in general, this is the first reported case of both recognition and naming deficits for these objects resulting from a single lesion. These results are consistent with research suggesting that the neuroanatomic substrates for the recognition and naming of unique objects lie in the anterior TL regions. Left temporal pole lesions have been associated with naming deficits for unique objects while right temporal pole lesions have been associated with recognition deficits for unique objects. However, these findings suggest that the substrates of naming can be located in homotopic regions of the right hemisphere when language lateralization is atypical. As various object categories appear to have different neuroanatomical representations in the TLs, we discuss the possible benefits of sampling a wider array of objects during cortical stimulation mapping of language.
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Papers by Daniel Drane