Prediction of Memory Impairment in Epilepsy Surgery by White Matter Diffusion

OBJECTIVE

To analyze the relationship between cognitive performance and white matter integrity in patients with temporal lobe epilepsy (TLE) to establish radiologic criteria to help with patient selection for surgery.

METHODS

The study included 19 adults with temporal lobe epilepsy. A tractography analysis of fractional anisotropy and mean diffusivity (MD) of the following fascicles was performed: arcuate fascicle, cingulum, fornix, inferior fronto-occipital fascicle, inferior longitudinal fascicle, parahippocampal fibers of the cingulum, and uncinate fascicle. The Wechsler Memory Scale-Third Edition neuropsychological test was performed to evaluate short- and long-term verbal (Logical Memory I and II subtests) and nonverbal (Visual Reproduction I and II subtests) memory. Relationships between memory scores and diffusion were calculated.

RESULTS

Lower Logical Memory I subtest scores were correlated with lower MD of the right inferior fronto-occipital fascicle, while lower Logical Memory II subtest scores were related to higher values of fractional anisotropy in bilateral cingulum, right uncinate, and right parahippocampal fibers of the cingulum and lower MD in left cingulum fascicle. Finally, lower values in Visual Reproduction I subtest scores were associated with lower values in MD in right cingulum and inferior fronto-occipital fascicles.

CONCLUSIONS

Structural changes of some white matter tracts were associated with deterioration of both short- and long-term memory. These alterations were more associated with verbal memory than with nonverbal memory. These changes mainly consist of an increase in fractional anisotropy and a decrease in MD, which could be interpreted as reorganization phenomena. Diffusion tensor imaging could be a useful tool for cognitive assessment in surgical candidates with temporal lobe epilepsy who are not suitable for neuropsychological testing or in whom their results do not lead to definitive conclusions.

Alteration profile of executive functions in multiple sclerosis

OBJECTIVE

Executive functions (EF) in multiple sclerosis (MS) have been only partially studied, mainly trough the evaluation of subfunctions. The main objective was to analyse the EF alteration profile in a patients with MS sample.

PARTICIPANTS AND METHODS

Case-control study, 100 patients with MS and 30 controls were evaluated by the following tests: Comprehensive Trail Making Test, Stroop Test, Wisconsin Card Sorting Test, picture completion, letter-number sequencing, comprehension and similarities of the WAIS-III scale, phonological and semantic fluency, zoo map test, temporal judgment and behavioural Dysexecutive Questionnaire (DEX-Q) of the Behavioural Assessment of the Dysexecutive Syndrome. Scores below normative values were considered pathological. Factorial analysis was used to simplify the deficits, and multiple regression and ANOVA statistics were used to analyse the relationship between clinical and cognitive variables.

RESULTS

Seventy-four patients had a recurrent-relapsing course, the mean degree of disability by Expanded disability Status Scale (EDSS) was 2.7 and the mean time of evolution was 9.94 years. Eighty-five per cent presented alterations in 3 or more EF tests and 71% in 5 or more. In the factorial analysis, three groups of functions were involved: (i) cognitive flexibility (ii) inhibition and (iii) abstraction ability. Patients with a progressive course and a high EDSS had a significantly worse performance (P < 0.05). The patients showed a low awareness of their deficit in the DEX-Q.

CONCLUSIONS

Cognitive flexibility, inhibition and abstraction ability were the three components of EF most deficient. The patients with the worst performance were those with progressive forms and a high EDSS.

Executive function and memory in patients with relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system very heterogeneous in its characteristics. In contrast to the well known sensitive/motor deficits, the cognitive dysfunction has only been analyzed in the last few decades. Attention, executive function, and memory were assessed in 28 patients with recurrent-remittent MS (RRMS) (duration, median 7 years; EDSS median 2) by means of a specific neuropsychological battery. Depression (BDI), anxiety (STAI) and fatigue (FSS) were also assessed. Twenty-five of these patients were selected for statistical study because they presented deficits in some cognitive areas. Twenty-four percent of the patients displayed memory deficits and 80% showed attention and executive function deficits related to prefrontal lobe function. No global memory difficulties were found, except for immediate visual memory of complex elements (immediate recall of the Rey figure), although the visual reproduction I subtest of the WMS-R was unaffected. In RRMS patients with a relatively short duration and low level of incapacity, cognitive impairments mainly affected prefrontal functions. The difficulties in immediate visual memory of complex elements could also be explained by a failure in these areas, due to the alteration of the organization and strategic use of the material to be encoded.

Neuropsychological evidence for "word-meaning deafness" in a Spanish-speaking patient

In this paper we present a case of "word-meaning deafness," characterised by serious problems in the comprehension of spoken language, whilst repetition and writing words and non-words from dictation are preserved. This performance indicates the impossibility of correctly accessing phonological representation from the semantic representation of words. Neuropsychological evidence on specific alterations in word-meaning disorders is scarce, and this study contributes new findings with a Spanish-speaking patient. The nature of the processes involved in understanding language and the cerebral mechanisms that might be affected in each case were discussed, in accordance with current neuropsychological theories.