Christian Dow

Cognitive prognosis in chronic temporal lobe epilepsy

First, to determine whether patients with chronic temporal lobe epilepsy have a different cognitive trajectory compared to control subjects over a prospective 4‐year interval; second, to determine the proportion of patients who exhibit abnormal cognitive change and their profile of demographic, clinical epilepsy, and baseline quantitative magnetic resonance imaging characteristics; and third, to determine the most vulnerable cognitive domains.

Ipsilateral and Contralateral MRI Volumetric Abnormalities in Chronic Unilateral Temporal Lobe Epilepsy and their Clinical Correlates

Summary:  Purpose: To assess the presence, extent, and clinical correlates of quantitative MR volumetric abnormalities in ipsilateral and contralateral hippocampus, and temporal and extratemporal lobe regions in unilateral temporal lobe epilepsy (TLE).

Relationship between information processing speed in temporal lobe epilepsy and white matter volume

Abnormalities in white matter have been linked to processing speed impairment in clinical populations (e.g., multiple sclerosis, closed head injury). Recent studies indicate the presence of significant reduction in cerebral white matter volume in some patients with chronic temporal lobe epilepsy (TLE). The objective of this study was to examine the relationship between white matter volume and processing speed and performance efficiency on the Sternberg Memory Scanning Test (SMST). The study groups included TLE subjects with white matter volume reduction (n=13), TLE subjects with normal white matter volume (n=14), and healthy controls (n=18). The groups did not differ in total cerebral gray matter volume. Compared with the controls, the reduced white matter volume TLE group exhibited a significantly steeper slope on the SMST. This was characterized by a disproportionate increase in reaction time with increased processing demands (set size), particularly for negative probe trials. In contrast, no significant differences on the SMST were evident between controls and the normal white matter volume TLE group. These findings suggest the presence of information processing speed and efficiency impairment in TLE and its relationship with white matter volume integrity.

A Controlled Quantitative MRI Volumetric Investigation of Hippocampal Contributions to Immediate and Delayed Memory Performance

MRI volumetric TLE studies show inconsistent evidence of hippocampal involvement in memory. Prior studies have not dissociated hippocampal and temporal lobe contributions to memory. We measured hippocampal and temporal lobe volumes and immediate/delayed memory performances in 64 TLE patients. Regression was used to dissociate hippocampal from temporal lobe contributions to memory. Results revealed reliable evidence for dominant hippocampal involvement in delayed verbal recall across three separate measures and less consistent evidence for nondominant hippocampal involvement. The findings point to a consistent relationship of dominant hippocampal volumes to delayed verbal recall but no involvement of the temporal lobe or nondominant hippocampus in memory.

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.

Narrative and procedural discourse in temporal lobe epilepsy

It is well established that some individuals with temporal lobe epilepsy (TLE) demonstrate language deficits at the single word level. However, discourse production rarely has been examined quantitatively within this group. This study compared adult TLE patients with an early seizure onset (< or = age 14 years, n = 27) to a control group (n = 28) on narrative and procedural discourse tasks. As a group, the TLE patients performed normally on the procedural discourse task, but differed significantly from the controls on several narrative discourse variables. At the individual level, 30% of the TLE patients versus 4% of the controls demonstrated impaired discourse ability (p and 0.01). Within this early onset TLE group, discourse performance was not associated with demographic or seizure history variables. Considering the cognitive domain, discourse performance correlated significantly with working memory. In summary, mild discourse dysfunction was present in a significant minority of early onset TLE patients, but this deficit was not closely associated with other language measures. Discourse ability and its neuropsychological, neuroanatomical and conversational speech correlates deserve further study in TLE patients.

Negative symptoms and psychosocial status in temporal lobe epilepsy

PURPOSE To determine the relationship between negative symptoms, psychosocial function and quality of life in temporal lobe epilepsy. METHODS 23 patients with temporal lobe epilepsy with negative symptoms were matched on gender, age, years of education, duration and age of epilepsy onset with 23 temporal lobe epilepsy patients exhibiting no negative symptoms as determined by a standardized rating system (SANS/SAPS). The matched groups were compared in regard to: (1). employment status, (2). dependence on government financial subsidy, (3). relationship/marital status, and (4). self-reported quality of life. RESULTS Temporal lobe epilepsy patients with negative symptoms exhibited higher rates of unemployment, dependence on government aid, social isolation, and poorer self-reported quality of life relative to temporal lobe patients without negative symptoms. CONCLUSIONS Interictal negative symptoms are associated with significantly increased psychosocial morbidity and poorer quality of life in temporal lobe epilepsy.

Measuring Clinical Significance in Rehabilitation Research.

Measurement of clinically significant change is critical for rehabilitation research because it can enhance the credibility of rehabilitation efforts and guide evidence-based practices. The practical appeal of clinically significant change is that it can bridge research and clinical practice by focusing on individual rather than group differences. In response to current challenges in rehabilitation outcome measurement, the authors describe methods and strategies for the analysis of clinically significant change. The complementary approaches of reliable change index scores as proposed by Jacobson and Truax (1991) and regression-based z scores as proposed by McSweeney, Naugle, Chelune, and Luders (1993) are highlighted. The article concludes with a case example and discussion of implications for future directions in rehabilitation research.