Magnetic resonance imaging and cognitive functioning in multiple sclerosis

Focus or Neglect on Cognitive Impairment Following the History of Multiple Sclerosis

Cognitive disorders are now considered an integral part of the picture of multiple sclerosis. If we trace the history of the accounts of this disease, from the early descriptions by Jean-Martin Charcot, the first to provide systematic characteristics of multiple sclerosis, to present-day accounts, reports of cognitive disturbances have demonstrated an alternating trend. Cognitive disturbances were identified in the beginning, quite clearly for the times. Then, for a long time, they were considered infrequent or attributed to other factors. Finally, since the 1980s, cognitive disturbances have been the subject of increasingly in-depth studies, and are currently assumed to be a very important consequence of multiple sclerosis. In this work, the history of the description of cognitive disorders of multiple sclerosis will be retraced by analyzing the possible reasons for the differences in attention they have received over time. It emerged from the analysis that, as in the case of other pathologies, various factors have influenced how cognitive disorders have been taken into consideration. Some of these factors are inherent to the very nature of the cognitive impairments present in multiple sclerosis; others are linked to historical periods, or to the different ways of approaching the analysis of the phenomena caused by a disease. The reflections made on these topics should, among other things, increase our awareness of how scientific investigation is invariably placed in the historical context in which it is carried out.

Multiple sclerosis lesion detection using constrained GMM and curve evolution

This paper focuses on the detection and segmentation of Multiple Sclerosis (MS) lesions in magnetic resonance (MRI) brain images. To capture the complex tissue spatial layout, a probabilistic model termed Constrained Gaussian Mixture Model (CGMM) is proposed based on a mixture of multiple spatially oriented Gaussians per tissue. The intensity of a tissue is considered a global parameter and is constrained, by a parameter-tying scheme, to be the same value for the entire set of Gaussians that are related to the same tissue. MS lesions are identified as outlier Gaussian components and are grouped to form a new class in addition to the healthy tissue classes. A probability-based curve evolution technique is used to refine the delineation of lesion boundaries. The proposed CGMM-CE algorithm is used to segment 3D MRI brain images with an arbitrary number of channels. The CGMM-CE algorithm is automated and does not require an atlas for initialization or parameter learning. Experimental results on both standard brain MRI simulation data and real data indicate that the proposed method outperforms previously suggested approaches, especially for highly noisy data.

Neuropsychological impairment in multiple sclerosis patients: the role of (juxta)cortical lesion on FLAIR

In this study we evaluated the correlation between neuropsychological impairment (measured with the Brief Repeatable Battery Neuropsychological Tests) and (juxta)cortical lesions detected with FLAIR and the relative sensitivity of the FLAIR sequence compared to spin-echo MRI sequences in detecting (juxta)cortical MS lesions. A total of 39 patients with definite MS were evaluated by MRI with a conventional and fast spin echo sequence and fast FLAIR sequence, and neuropsychological tests of the Brief Repeatable Battery Neuropsychological tests were performed. The Z-score of all subtests were used to calculate a Cognitive Impairment Index. The results show that a high number of (juxta)cortical lesions is detected with thin slice FLAIR (30% of all lesions seen). This percentage was not superior to spin-echo, reflecting the thin slice thickness (3 mm) we used. The lesions detected with FLAIR were to a certain degree different ones than the lesions detected with the other techniques. While the number of non-cortical lesions correlated with the expanded disability status scale (r=0.32, P=0.045), the number of (juxta)cortical lesions detected with the FLAIR showed a correlation (r=0.34, P=0.035) with the Cognitive Impairment Index. Our study underlines the high number of (juxta)cortical lesions in MS and the value of thin slice FLAIR sequence to detect such lesions with MRI. It also stresses the importance of (juxta)cortical lesions on determining neuropsychological impairment. Multiple Sclerosis (2000) 6 280 - 285

Immediate recovery of cognitive functions and resolution of fatigue by treatment with weak electromagnetic fields in a patient with multiple sclerosis

Cognitive deficits are common among patients with multiple sclerosis (MS). The pathogenetic mechanisms underlying the cognitive impairment in MS are unknown and there is presently no effective therapeutic modality which has shown efficacy in improving cognitive deficits in MS. A 53 year old college professor with a long history of secondary progressive MS experienced, over the preceding year, noticeable deterioration in cognitive functions with difficulties in short and long term memory, word finding in spontaneous speech, attention and concentration span. Unable to pursue his academic activities, he was considering early retirement. Mental examination disclosed features of subcortical and cortical dementia involving frontal lobe, left hemispheric and right hemispheric dysfunction. Almost immediately following the extracerebral application of AC pulsed electromagnetic fields (EMFs) of 7.5 picotesla intensity and a 4-Hz sinusoidal wave, the patient experienced a heightend sense of well being, which he defined as enhancement of cognitive functions with a feeling "like a cloud lifted off my head." He reported heightend clarity of thinking and during the application of EMFs he felt that words were formed faster and he experienced no difficulty finding the appropriate words. His speech was stronger and well modulated and he felt "energized" with resolution of his fatigue. There was improvement in manual dexterity and handwriting and testing of constructional praxis demonstrated improvement in visuospatial, visuoperceptive and visuomotor functions. It is suggested that some of the cognitive deficits associated with MS, which are caused by synaptic disruption of neurotransmitter functions, may be reversed through pulsed applications of picotesla range EMFs.

Neuropsychological assessment in multiple sclerosis: methodological issues and concerns

A brief overview of research findings in five key areas pertaining to the study of neuropsychological aspects of multiple sclerosis is presented. The areas covered are: (1) general and specific cognitive deficits (2) prevalence of these deficits (3) attempts to correlate these deficits with clinicopathological features (4) attempts to investigate the relationship between deficits and abnormalities detected on magnetic resonance scanning and (5) longitudinal studies of cognitive deficits and MS. Based on this review, methodological issues that continue to hinder comparison between research reports, and across research centres, are outlined. Problem areas identified are (1) patient selection (2) selection of control subjects (3) lack of consensus regarding test selection (4) problems with statistical procedures (5) the relationship between depression and cognition (6) problems with measuring disability and MR abnormalities and (7) lack of longitudinal data.

Cognitive-linguistic assessment of individuals with multiple sclerosis

Four individuals diagnosed as having multiple sclerosis (MS) and four matched controls were assessed with the Arizona Battery for Communication Disorders (ABCD), a standardized battery of memory and cognitive-linguistic tasks. Subjects with MS and controls performed in an equivalent or nearly equivalent fashion for nine of the ABCD subtests. For five of the subtests (Object Description, Generative Naming, Concept Definition, Generative Writing, and Picture Description), subjects with MS performed substantially lower than the control subjects. Results of this pilot study suggest that portions of the ABCD may be useful in identifying profiles of memory, and cognitive-linguistic impairment among individuals with multiple sclerosis. Further research using a larger sampling of individuals with MS is needed to more fully assess the usefulness of the ABCD with this population.

Anatomical and functional correlates of cognitive deficit in multiple sclerosis

This brief article reviews the present state of knowledge concerning the relationship between structural and functional cerebral abnormalities and the cognitive deficits associated with multiple sclerosis. Currently available neuroimaging techniques have substantially contributed to a better understanding of the latter, suggesting that cortical-subcortical disconnection is the most likely cause of the cognitive disturbance. Longitudinal studies are needed to determine the natural history of the cognitive deficit and its relationship to the cerebral changes detected by neuroimaging techniques.

MRI and cognitive patterns in relapsing-remitting multiple sclerosis

We studied the relationships between magnetic resonance imaging (MRI) and the Luria-Nebraska Neuropsychological Battery (LNNB) in 64 patients with relapsing-remitting multiple sclerosis (MS). MRI films were scored according to arbitrary descriptive criteria designed to emphasize patterns of alterations. Five groups were created: group 1 and 2 had typical discrete white matter lesions, group 3 had confluent lesions, group 4 had large discrete lesions and group 5 had only few small lesions. In addition, groups 2 and 3 had evidence of parenchymal atrophy. Groups 2 and 3 were the most impaired on the LNNB, but none of these patients was actually demented. Groups 1 and 5 were globally intact in spite of very different mean age and MRI pattern. Group 4 was composed of younger subjects with a shorter disease duration; they showed mild loss of attentive and abstracting abilities. We suggest that since their MRI was showing greater signs of local biological activity their mental deficits may be a transitory condition capable of two distinct outcomes: a favorable one as in groups 1 and 5, and a slowly progressive one associated with loss of brain tissue as in groups 2 and 3.

Brain magnetic resonance imaging correlates of cognitive impairment in multiple sclerosis

We evaluated the correlations between cognitive impairment, clinical and brain magnetic resonance imaging (MRI) findings in 100 patients with multiple sclerosis (MS). The performance on one or more neuropsychological tests was abnormal in 47% of the 64 patients who completed the entire neuropsychological battery; the cognitive impairment was mild in 14 (22%) and severe in 16 (25%). Performance on any single neuropsychological test was unrelated to clinical parameters (age, duration of the disease, disability). The neuropsychological performance of relapsing-remitting patients was better than in patients with a chronic-progressive disease. The mean scores for almost all the neuropsychological tests were significantly lower in patients with severe ventricular dilatation and corpus callosum atrophy than in patients in whom these structures were little affected. Mean scores for WMS, performance Intelligence Quotient (IQ), total IQ and Token Test (TT) were also significantly correlated with the widening of cortical sulci and total lesional scores. Our data support the contention that the involvement of pathways that are critical for a given cognitive process as well as the progression of the axonal degeneration and sclerosis seem to play important roles in the pathophysiology of cognitive dysfunction in MS.

Endogenous event-related potentials as indices of dementia in multiple sclerosis patients

Auditory event-related potentials (ERPs) were recorded in a "double oddball" paradigm requiring an easy and a hard pitch discrimination from multiple sclerosis (MS) patients with and without dementia, and a group of age and sex matched normal subjects. Cognitive function was assessed by a short battery of neuropsychologic (NP) tests, and the two groups of MS patients were selected on the basis of substantial non-overlapping degrees of cognitive deficit in the demented as compared to the non-demented group. The N100, P200 and P300 ERP components were longer in latency in the demented patients, and the N100-P300 interval was prolonged as well, compared to the non-demented patients, whose ERP latencies did not differ from those of the normal subjects. Increased P300 latency was associated with poorer performance on the NP tests, especially those sensitive to impairment of learning and retrieval from memory. The reaction times of both patient groups were prolonged as compared to the controls, whereas the accuracy of the demented patients was significantly poorer than that of the non-demented patients.

Neuropsychological assessment in multiple sclerosis: a follow-up study with magnetic resonance imaging

Nineteen moderately impaired patients with clinically definite multiple sclerosis and an initially relapsing-remitting course were included in a neuropsychological and magnetic resonance imaging (MRI) follow-up study. The average test/re-test interval was about 2 years. The neuropsychological findings were indicative of a very mild overall impairment; the patients, as a group, showed no evidence of cognitive deterioration in the follow-up period. A numerical estimation of the severity of cerebral demyelination shown by MRI did not indicate a significant change. No correlation between cognitive performance variations and MRI changes was found.

Anterior corpus callosum atrophy and verbal fluency in multiple sclerosis

To determine whether different portions of the corpus callosum (CC) are responsible for transferring the information of specific cognitive modalities, eighteen females with relapsing-remitting Multiple Sclerosis (MS) were studied using neuropsychological procedures and Magnetic Resonance Imaging (MRI). Measures of both anterior and posterior CC areas were obtained in patients with MS as well as in eighteen age and sex matched healthy controls. MRI scans were additionally analyzed for each patient in order to evaluate the extent of demyelinating lesions in both periventricular and subcortical areas. Patients with MS exhibited a significant decrease in both the anterior and posterior CC areas compared with normal subjects. The results of statistical analysis showed that, even when the effect of demyelinating lesions was taken into account within a regression equation, the atrophy of anterior CC area strongly affected the performance on verbal fluency task. These data emphasize the importance of the anterior CC area for the interhemispheric transfer of cognitive information associated with verbal fluency.

SPECT, MRI and cognitive functions in multiple sclerosis

Seventeen patients with relapsing remitting multiple sclerosis (MS) and mild physical disability had neuropsychological testing, magnetic resonance imaging (MRI) and single photon emission computerised tomography (SPECT) using technetium 99m (99mTc) hexamethyl-propyleneamine oxime (HMPAO). Performance in verbal fluency, naming and memory testing appeared to be impaired in MS patients compared with 17 age-sex and education matched normal controls. Weighted periventricular and confluent lesion scores and the width of the third ventricle, proved to be the most sensitive MRI measures in differentiating more cognitively impaired patients from those who were relatively unimpaired. Ratios of regional to whole brain activity, measured by SPECT, showed significant reduction in the frontal lobes and in the left temporal lobe of MS patients. A relationship was found between left temporal abnormality in 99mTc-HMPAO uptake and deficit in verbal fluency and verbal memory. Finally, asymmetrical lobar activity indicated a predominant left rather than right temporo-parietal involvement.

Neuropsychological assessment in patients with relapsing-remitting multiple sclerosis and mild functional impairment: correlation with magnetic resonance imaging

Forty one moderately impaired patients with clinically confirmed multiple sclerosis (MS) and a relapsing-remitting course were submitted to a neuropsychological battery and magnetic resonance imaging (MRI) to correlate the neuropsychological performances with the degree of cerebral demyelination. The neuropsychological results were indicative of a very mild overall impairment. The patients were subdivided into two groups (extensive periventricular demyelination or discrete lesions on MRI) and the results of neuropsychological tests compared. Patients with extensive periventricular demyelination had an inferior performance on concept formation, non-verbal reasoning and verbal memory tests.

Structural brain correlates of anterograde memory deficits in multiple sclerosis

Progressive decline of anterograde memory functions has been increasingly recognized as a frequent symptom in chronic multiple sclerosis. In order to investigate the brain structures involved, magnetic resonance imaging was performed in 20 patients. Neuropsychological assessment included the WAIS and WMS subtests information, picture completion, similarities, digit span, logical memory, and paired associate learning. All patients with severely impaired memory functions (n = 5) showed bilateral lesions in the medial temporal lobe, whereas in those patients with moderate (n = 10) or no measurable impairment of memory testing (n = 5) either no lesions were seen in the medial temporal lobes or these lesions were restricted to one side. A post hoc cluster analysis strikingly confirmed these results. The differences could not be related to the age of the patients, the disease duration, or the level of education. Extensive lesions in the white matter of the frontal lobes, thinning and lining of the corpus callosum, and bilateral involvement of the anterior cingulate gyrus had no bearing on the neuropsychological results. These findings indicate that bilateral demyelination in the hippocampal regions is the most likely explanation for the impairment of anterograde memory in such patients.