Quantitative and qualitative interpretation of neuropsychological data in the assessment of temporal lobectomy candidates.

Neuropsychologists who serve as members of an epilepsy surgery team are often asked to provide information regarding localized cerebral dysfunction that may relate to the seizure focus in patients with intractable temporal lobe epilepsy (TLE). However, the rate at which neuropsychological (NP) assessment results correspond with the side of seizure focus (i.e., left vs. right) in TLE patients is unknown. The majority of literature in this area has focused on the ability of single NP tests to detect lateralized cognitive dysfunction in groups of TLE patients, with mixed findings and few consistent replications. The primary purpose of this study was to examine the rate at which qualitative clinician interpretations of NP profiles agree with seizure lateralization as determined by a multidisciplinary surgery team in temporal lobectomy candidates. Quantitative analyses of single NP test scores and groups of test scores (i.e., cognitive domain composite scores) were also conducted to examine their effectiveness in discriminating left from right TLE groups. Only four of the 19 NP test variables and three of the nine composite cognitive domain scores significantly differed between the groups. However, clinician interpretation of NP profiles agreed with the surgery conference team's determination of seizure laterality in two-thirds of cases. These findings suggest that qualitative aspects of NP performance play an important role in identifying lateralized cerebral dysfunction in TLE patients, and provide additional support for the use of NP assessment results in the selection of temporal lobectomy candidates.

Effects of practice on category fluency in Alzheimer's disease.

Evaluation of patients with suspected Alzheimer's disease (AD) often involves clinicians of multiple disciplines working in collaboration to maximize diagnostic accuracy. Accordingly, repeated administrations of some common tests of mental status may occur within a relatively brief time period. The effect of such retesting on subsequent results is largely unknown for many cognitive tasks, despite the possibility that repeated administrations may artificially inflate scores. To assess the potential impact of practice effects on a commonly administered verbal fluency task, animal naming was administered twice within a 1-week period to 111 patients with probable AD and 12 persons without dementia. Non-demended subjects were the only group to demonstrate a small (3 point), but statistically significant practice effect. Regardless of level of cognitive impairment, patients with AD did not show significant practice effects over repeated administrations of animal naming after a relatively brief test-retest interval, suggesting the robust nature of this task in AD.

Comparative analysis of qualitative verbal fluency performance in normal elderly and demented populations.

Verbal fluency tasks are commonly used in the assessment of patients with known or suspected dementia. Whereas total word production is often analyzed, less attention has been paid to qualitative aspects of verbal fluency performance. The purpose of this study was to examine the diagnostic utility of a qualitative scoring technique for semantic and phonemic fluency tasks in individuals with Alzheimer's disease (AD), Parkinson's disease (PD) with and without dementia, and in a group of older normal controls (ONC). In addition to total words produced, the groups were compared on their use of clustering (i.e., ratio of words generated within subcategories) and switching (i.e., frequency of shifts between clusters) strategies as originally defined by Troyer et al. (1997a). In terms of total number of words produced, controls were superior to the AD and demented PD subjects, who performed similarly. A similar trend was found in relation to switching and clustering scores. PD patients without dementia performed similar to the ONC group on semantic fluency, but were impaired relative to controls on all phonemic fluency variables (i.e., total words produced, clustering, switching). Discriminant function analyses using the three fluency variables revealed that total words was equal to or surpassed the other variables in distinguishing the groups, suggesting that these qualitative verbal fluency features may not provide significant additional information in terms of diagnostic utility.