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Reduced brain functional reserve and altered functional connectivity in patients with multiple sclerosis.

Cognitive dysfunction (affecting particularly attention and working memory) occurs early in patients with multiple sclerosis. Previous studies have focused on identifying potentially adaptive functional reorganization through recruitment of new brain regions that could limit expression of these deficits. However, lesion studies remind us that functional specializations in the brain make certain brain regions necessary for a given task. We therefore have asked whether altered functional interactions between regions normally recruited provide an alternative adaptive mechanism with multiple sclerosis pathology. We used a version of the n-back task to probe working memory in patients with early multiple sclerosis. We applied a functional connectivity analysis to test whether relationships between relative activations in different brain regions change in potentially adaptive ways with multiple sclerosis. We studied 21 patients with relapsing-remitting multiple sclerosis and 16 age- and sex-matched healthy controls with 3T functional MRI. The two groups performed equally well on the task. Task-related activations were found in similar regions for patients and controls. However, patients showed relatively reduced activation in the superior frontal and anterior cingulate gyri (P > 0.01). Patients also showed a variable, but generally substantially smaller increase in activation than healthy controls with greater task complexity, depending on the specific brain region assessed (P < 0.001). Functional connectivity analysis defined further differences not apparent from the univariate contrast of the task-associated activation patterns. Control subjects showed significantly greater correlations between right dorsolateral prefrontal and superior frontal/anterior cingulate activations (P < 0.05). Patients showed correlations between activations in the right and left prefrontal cortices, although this relationship was not significant in healthy controls (P < 0.05). We interpret these results as showing that, while cognitive processing in the task appears to be performed using similar brain regions in patients and controls, the patients have reduced functional reserve for cognition relevant to memory. Functional connectivity analysis suggests that altered inter-hemispheric interactions between dorsal and lateral prefrontal regions may provide an adaptive mechanism that could limit clinical expression of the disease distinct from recruitment of novel processing regions. Together, these results suggest that therapeutic enhancement of the coherence of interactions between brain regions normally recruited (functional enhancement), as well as recruitment of alternative areas or use of complementary cognitive strategies (both forms of adaptive functional change), may limit expression of cognitive impairments in multiple sclerosis.

Adaptation, Psychological↗

Increased IL-23p19 expression in multiple sclerosis lesions and its induction in microglia.

IL-12 has long been considered important in the pathogenesis of multiple sclerosis. However, evidence from recent studies strongly supports the critical role of IL-12-related proinflammatory cytokine IL-23, but not IL-12, in the development of experimental autoimmune encephalomyelitis (EAE), an animal model of this disease. The role of IL-23 in the CNS immunity of multiple sclerosis patients has not been elucidated; nor is it known whether human microglia produce this cytokine. In this study we investigated the expression of IL-23p19 and p40, with its key subunit p19 as the focus, in histologically characterized CNS specimens from multiple sclerosis and control cases using in situ hybridization and immunohistochemistry. A significant increase in mRNA expression and protein production of both subunits of IL-23 was found in lesion tissues compared with non-lesion tissues. Double staining showed that activated macrophages/microglia were an important source of IL-23p19 in active and chronic active multiple sclerosis lesions. We also detected IL-23p19 expression in mature dendritic cells which were preferentially located in the perivascular cuff of active lesions. The finding that human microglia produce IL-23 was further confirmed by the inducible production of IL-23p19 and p40 in cultured human microglia in vitro upon different Toll-like receptor stimulations. Taken together, these findings on the expression of IL-23p19 in multiple sclerosis lesions may lead to a better understanding of the events culminating in human multiple sclerosis.

Adult↗

Estimating the prevalence of multiple sclerosis in the United Kingdom by using capture-recapture methodology.

The geographic distribution of multiple sclerosis is nonrandom, as the disease is more prevalent in temperate than in tropical regions. Surveys conducted between 1970 and 1996 suggest that multiple sclerosis is more prevalent in the northern part of the United Kingdom than in the southern part. This north-south gradient ("the latitudinal gradient") might be a methodological artifact, because high prevalence figures from serial surveys of the northern part of the United Kingdom might have been the result of better ascertainment. By using capture-recapture methods, the authors found that case ascertainment was similar in the northern and southern parts of the United Kingdom. When prevalence figures for multiple sclerosis in the southern United Kingdom were increased to account for the number of unobserved cases, the difference persisted: The prevalence of multiple sclerosis in the northern part of the United Kingdom appeared to be at least 180 cases per 100,000 persons, whereas the maximum prevalence in the southern part of the United Kingdom was less than 160 cases per 100,000 persons. The distribution of multiple sclerosis in the United Kingdom is not uniform and is consistent with the hypothesis that populations with a high prevalence of multiple sclerosis may be genetically predisposed to the disease.

Adult↗

Amyotrophic lateral sclerosis and parkinsonism-dementia on Guam: a 25-year prospective case-control study.

Familial and genetic studies of high-incidence amyotrophic lateral sclerosis and parkinsonism-dementia among the Chamorro people of Guam were initiated in 1958 with the establishment of a prospective case-control registry. The major objective of this registry was to determine if first-degree relatives and spouses of patients with amyotrophic lateral sclerosis or parkinsonism-dementia had an increased risk of developing disease compared with relatives of nonaffected controls individually matched for age, sex, and village. At the time of its closing in 1963, the registry included 126 patients (77 with amyotrophic lateral sclerosis, 42 with parkinsonism-dementia, and seven with both amyotrophic lateral sclerosis and parkinsonism-dementia) and an equal number of controls; 994 living first-degree relatives (parents, siblings, and offspring) of patients and 1,218 of controls; and 88 living spouses of patients and 101 of controls. The present analysis of the 25-year follow-up study (1958-1983) demonstrated a significantly increased risk of developing amyotrophic lateral sclerosis or parkinsonism-dementia among parents, siblings, and spouses of patients, but not among relatives of controls. Offspring of both patients and controls showed no significantly increased risk of developing disease. The increased risk among spouses of patients and the lack of increase among their offspring, together with recent histochemical findings, support the contention that exogenous factors are strong contributors to the etiology of amyotrophic lateral sclerosis and parkinsonism-dementia. The present results also demonstrate a declining incidence of both diseases.

Aged↗

Using isokinetic dynamometry to test ambulatory patients with multiple sclerosis.

This study was designed to 1) determine whether isokinetic dynamometry is appropriate and safe for ambulatory patients with multiple sclerosis and 2) describe the idiosyncrasies the patients with multiple sclerosis exhibited during testing. Ten patients with multiple sclerosis and 20 healthy subjects were matched for age, sex, and weight. The isokinetic peak torque and endurance measurements of knee extensor and knee flexor muscles were recorded at selected angular velocities ranging from 0 to 275 degrees/sec and extensor:flexor muscle strength ratios were calculated. Statistical analysis (t tests) revealed that both the extensor and flexor muscle peak torque values for patients with multiple sclerosis were significantly lower than those for healthy subjects at all angular velocities (p less than .005 to p less than .001), and yet were similar in shape and slope. Mean extensor:flexor ratios for healthy subjects and for patients with multiple sclerosis were not significantly different at 70, 190, and 230 degrees/sec. Individual chart recordings identified any contractile difficulties or increased contraction time. Isokinetic testing is judged to be a safe and reliable form of objective neuromuscular testing for ambulatory patients with multiple sclerosis.

Adult↗

Multiple sclerosis and age at infection with common viruses.

Increased risk of multiple sclerosis has been reported among individuals with a history of measles and other common childhood diseases during adolescence, infectious mononucleosis, or exposure to the canine distemper virus. We investigated these associations in a case-control study nested within the Nurses' Health Study (121,700 women traced since 1976) and the Nurses' Health Study II (116,671 women traced since 1989). Age at diagnosis of common viral diseases and birth order were obtained through a questionnaire. Our results include 301 cases with multiple sclerosis and their (up to six) matched controls. Except for infectious mononucleosis, which was a moderate risk factor (odds ratio = 2.1, 95% confidence interval = 1.5-2.9), we found little association between history of common viral diseases or exposure to canine distemper virus and risk of multiple sclerosis. We did find a relation between mumps after 15 years of age (odds ratio = 2.3, 95% confidence interval = 1.2-4.3) or measles after age 15 years of age (odds ratio = 2.8, 95% confidence interval = 0.8-9.1) and multiple sclerosis. Birth order was not materially related to multiple sclerosis. Our findings support the hypothesis that individuals who suffered from infectious mononucleosis, a marker of late infection with the Epstein-Barr virus, have an increased risk of multiple sclerosis. Late infection with other common viruses may also be associated with increased risk.

Adult↗

Optokinetic reflex dysfunction in multiple sclerosis.

The aim of this study was to further investigate optokinetic reflex function in multiple sclerosis. Gaze-holding in darkness, optokinetic nystagmus, optokinetic afternystagmus and latency to circularvection were measured using electro-oculography and a rotating optokinetic drum. Gaze-holding was not significantly different between the multiple sclerosis and control groups; however, four of 23 multiple sclerosis patients exhibited eccentric gaze-evoked nystagmus. There were no significant differences in either optokinetic nystagmus frequency or latency to circularvection. However, optokinetic nystagmus slow phase velocity during rise time and amplitude during beat time were significantly reduced in the multiple sclerosis group (p < 0.05 and p < 0.0001, respectively). The time constant of optokinetic afternystagmus was also significantly reduced in the multiple sclerosis group (p < 0.005). These results indicate that optokinetic nystagmus and optokinetic afternystagmus are significantly impaired multiple sclerosis.

Adult↗

Physiologic and thermal responses of male and female patients with multiple sclerosis to head and neck cooling.

Personal cooling systems are used to alleviate symptoms of multiple sclerosis and to prevent increased core temperature during daily activities. The objective of this study was to determine the thermal and physiologic responses of patients with multiple sclerosis to short-term maximal head and neck cooling. A Life Support Systems, Inc. Mark VII portable cooling system and a liquid cooling helmet were used to cool the head and neck regions of 24 female and 26 male patients with multiple sclerosis in this study. The subjects, seated in an upright position at normal room temperature (approximately 22 degrees C), were cooled for 30 min by the liquid cooling garment, which was operated at its maximum cooling capacity. Oral, right, and left ear temperatures and cooling system parameters were logged manually every 5 min. Forearm, calf, chest, and rectal temperatures, heart rate, and respiration rate were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. This protocol was performed during the winter and summer to investigate the seasonal differences in the way patients with multiple sclerosis respond to head and neck cooling. No significant differences were found between the male and female subject group's mean rectal or oral temperature responses during any phase of the experiment. The mean oral temperature decreased significantly (P < 0.05) for both groups approximately 0.3 degrees C after 30 min of cooling and continued to decrease further (approximately 0.1-0.2 degrees C) for a period of approximately 15 min after removal of the cooling helmet. The mean rectal temperatures decreased significantly (P < 0.05) in both male and female subjects in the winter studies (approximately 0.2-0.3 degrees C) and for the male subjects during the summer test (approximately 0.2 degrees C). However, the rectal temperature of the female subjects did not change significantly during any phase of the summer test. These data indicate that head and neck cooling may, in general, be used to reduce the oral and body temperatures of both male and female patients with multiple sclerosis by the approximate amount needed for symptomatic relief as shown by other researchers. However, thermal response of patients with multiple sclerosis may be affected by gender and seasonal factors, which should be considered in the use of liquid cooling therapy.

Activities of Daily Living↗

Neuropsychological aspects of multiple sclerosis.

Twenty-six persons (five males and 21 females) with the neurological diagnosis of multiple sclerosis, and an equal number of control subjects matched on age, sex, and education were given a battery of tests designed to assess motor and intellectual functioning. Subjects in the multiple sclerosis group displayed marked deficits on all tests of motor skill except grip strength. Although verbal intelligence was not impaired in subjects with multiple sclerosis, these subjects performed more poorly than control subjects on two different tests of memory even though these tasks required minimal motor responsivity. Correlational analyses on the several motor and cognitive tasks revealed that correlations between motor and memory performance were consistently higher in persons with multiple sclerosis than in controls. These results suggest that whereas multiple sclerosis may not have mch effect on the utilization of stored verbal information, the processing and storage of new verbal material are disrupted by the disease to a degree that is paralleled by the extent of motor impairment. This finding is consistent with the view that the memory impairments observed are secondary to the primary motor deficit, but the alternative explanation that memory functions, like motor functions, are especially vulnerable to the demylination process of multiple sclerosis is equally viable at present.

Adult↗

Prevalence of idiopathic vertebral sclerosis, Zöetermeer, Rotterdam, 1975-1978.

In order better to define the prevalence and characteristics of idiopathic vertebral sclerosis, we evaluated the roentgenograms of 1,391 individuals greater than or equal to 35 years of age) for the presence or absence of idiopathic vertebral sclerosis. One hundred two radiographs showed evidence of idiopathic vertebral sclerosis, a prevalence rate of 5% in this population. For the first time, a roentgenographic classification is offered. These "cases" were then classified into Types I-IV, based on the pattern and location of the sclerosis. The radiologic and demographic characteristics of Type I correlate most closely with previous studies that have investigated the association of vertebral sclerosis with chronic back pain. Women predominated in age-specific classifications; the female-to-male ratio in Type I was 4:1, a reproducible finding in previous studies. The large sample available for study supports the conclusion that this is an accurate estimate of the prevalence rate of idiopathic vertebral sclerosis.

Adult↗

Viruses and multiple sclerosis.

Animal models illustrate how viruses and host genetic factors may interact to cause immune-mediated demyelination. Similar mechanisms may take place in at least some forms of multiple sclerosis, a disease that is histopathologically heterogeneous. No 'multiple sclerosis virus' has been found yet, although recent data on human herpesvirus-6 antigens in multiple sclerosis brain warrant further investigation. Multiple sclerosis associated retrovirus, a recently described retroviral sequence isolated from multiple sclerosis material, is a member of the endogenous retrovirus-9 family. The association between the expression of this virus associated retrovirus and multiple sclerosis is only tentative.

Animals↗

Concepts of viral pathogenesis of multiple sclerosis.

Viral infections have long been suspected to cause or modulate the pathogenesis of multiple sclerosis. Recently, two viruses in particular have been associated with multiple sclerosis: human herpesvirus-6 and a retrovirus termed multiple sclerosis-associated retrovirus, which is a member of the human endogenous retrovirus-9 family. Reports on the detection of human herpesvirus-6-encoded proteins in and around multiple sclerosis lesions are intriguing. Serological and polymerase chain reaction analyses looking for signs of reactivation of human herpesvirus-6 in multiple sclerosis patients are ambiguous, however. If human herpesvirus-6 does play a role as an initiator or amplifier of inflammatory lesions in some multiple sclerosis patients, these individuals might benefit from antiviral therapy.

Herpesviridae Infections↗

Multiple sclerosis: severity and progression rate in African Americans compared with whites.

OBJECTIVE: Although epidemiology indicates that multiple sclerosis is more common among whites than African Americans, the course of disease may be more aggressive among African Americans. This study examines disease course in a large multiple sclerosis clinic population. DESIGN: A case-controlled, retrospective record review compared the severity of multiple sclerosis for African Americans and for whites. Because the baseline demographics of the two groups differed, we performed analyses of multiple subgroups in an attempt to control for various characteristics. RESULTS: Consistent evidence of more disability in African Americans compared with whites was found, although subgroups were often too small to establish statistical significance. African Americans had a higher mean Expanded Disability Status Scale score than whites in a subgroup selected to minimize differences in access to care and disease perceptions. African Americans reported limb weakness as a presenting symptom of multiple sclerosis more frequently than did whites. When patients were followed at our multiple sclerosis center, rates of disease progression were nearly identical. CONCLUSIONS: More African Americans than whites experience pyramidal system involvement early in multiple sclerosis, leading to greater disability as measured by the ambulation-sensitive Expanded Disability Status Scale. Once patients have moderate difficulty walking, the rate of progression is the same for both groups, albeit occurring at a later age for whites than for African Americans.

Adult↗

Multiple paradigm shifts in multiple sclerosis.

PURPOSE OF REVIEW: The present article reviews the currently ongoing scientific debate of our changing views on the pathogenesis of multiple sclerosis and the therapeutic strategies currently available for multiple sclerosis. RECENT FINDINGS: The most important observations include that (a) axonal loss accounts for permanent disability in multiple sclerosis, (b) remyelination should be possible in theory but fails for unknown reasons in the multiple sclerosis lesion, (c) inflammation can be beneficial, (d) treatment should be initiated early, and (e) immunosuppressive strategies exhibit beneficial effects in progressive forms of the disease. SUMMARY: Our current understanding of the immunopathogenesis of multiple sclerosis has changed in the past. Whereas demyelination was originally thought to be relevant for the lasting neurological deficit, it is nowadays commonly accepted that the extent of axonal loss dictates the degree of permanent clinical disability. How axonal damage can be prevented remains elusive. The interaction between the myelinating cell and the neuron gains increasing attention, however the evolving knowledge has not yet yielded new treatment concepts. Hence for the time being, it seems prudent to make optimal use of current approved therapies. Recent trials underlined the need for early initiation of treatment with immunomodulatory drugs. The superiority of one of the interferons is still a matter of debate, and a conclusive answer cannot be given at present. Finally, with mitoxantrone we have a drug at hand which can be used in progressive forms of multiple sclerosis, especially when other disease modifying drugs are not or no longer effective.

Adjuvants, Immunologic↗

Progress in deciphering the genetics of multiple sclerosis.

PURPOSE OF REVIEW: Multiple sclerosis is the most common neurological disease affecting young adults. The aetiology is unknown, although many clues point to an autoimmune inflammatory nature. Family studies of multiple sclerosis have shown familial aggregation, and therefore suggest that the disease entails a genetic component that has been widely studied. Some of the studies from the extensive literature in the field of multiple sclerosis genetics published in the past year are discussed here. RECENT FINDINGS: A number of the recent publications considered in this review have reconfirmed the well-known association with the major histocompatibility complex as well as identifying that there are at least two important loci within this region. These findings add further complexity to the role of the major histocompatibility complex in multiple sclerosis. Links to other diseases have been few for multiple sclerosis, but the association with diabetes in the Sardinian population and, perhaps, a 'protective' effect of Down's syndrome can now be added. Numerous candidate genes for susceptibility and disease-modifying effect have also been studied in the literature, but with few replications. Associations with components of the endocrine and the neuro-endocrine system have also been considered in this review along with the potential value of microarray analysis. SUMMARY: Multiple sclerosis is a complex trait that is associated with the major histocompatibility complex, although the form of this association may not be as straightforward as previously thought. Recent findings raise the possibility of an association with haplotype blocks rather than with single alleles. The finding of allelic heterogeneity within the major histocompatibility complex, as with the Sardinians, adds an additional layer of complexity. Genome scans for this and other autoimmune diseases have often been notably disappointing despite many claims for linkages. The reasons for the difficulty may encompass locus heterogeneity, small effects and phenocopies, among others. A variety of attempts to study more restricted populations are in progress, including rare individual pedigrees with high recurrence risk.

Diabetes Mellitus↗

Current management for epilepsy in tuberous sclerosis complex.

PURPOSE OF REVIEW: This article reviews the most significant advances in the field of epilepsy associated with tuberous sclerosis complex, with emphasis on new advances in the knowledge of the pathophysiological mechanisms of epileptogenicity, progress in identifying the epileptogenic zone, and the rationale for surgical management in individuals with intractable seizures. RECENT FINDINGS: Advances in our understanding of the mechanisms and genetics underlying infantile spasms and catastrophic epilepsy associated with tuberous sclerosis complex may facilitate more effective interventions. Early effective seizure control could significantly reduce the adverse developmental effects of chronic epilepsy in tuberous sclerosis. Vigabatrin is the first choice in the short-term treatment of infantile spasms. Some individuals, however, develop seizures that remain highly intractable. The factors that influence the intractability of epilepsy associated with tuberous sclerosis complex remain poorly understood. Multimodality neuroimaging has improved detection of epileptogenic foci, allowing an increased number of individuals to be evaluated for resective surgery. Epilepsy surgery is often associated with significant improvement of the neurologic outcome. SUMMARY: Epilepsy in tuberous sclerosis seems to arise from the interaction between multiple areas, all of which have increased excitability and reduced inhibition. Understanding the mechanisms of epileptogenesis might increase the availability of development of a more specific and efficacious treatment. New evidence suggests that it is possible to noninvasively identify children with tuberous sclerosis who are highly likely to become seizure free following surgical treatment.

Animals↗

Neuroprotection in multiple sclerosis: therapeutic strategies and clinical trial design.

PURPOSE OF REVIEW: Degeneration of axons and their cell bodies is thought to occur progressively from the onset of multiple sclerosis and to be a significant cause of increasing disability. The mechanisms of neurodegeneration are becoming clearer and this work has already indicated potential molecular targets for therapeutic intervention to prevent neuronal injury. Attention is being directed at the appropriate design of clinical trials to test neuroprotection as a major strategy for the management of multiple sclerosis. The subtype of multiple sclerosis, the primary outcome measure and other detailed design issues remain controversial. This review considers the rationale for different therapeutic strategies for neuroprotection and discusses the controversies of trial design. RECENT FINDINGS: The experimental work on neuroprotection in animal models of inflammatory axonal degeneration and consideration of outcome measurement in multiple sclerosis have developed sufficiently to enable trials of neuroprotection to be planned, powered and implemented. Trials assessing neuroprotection with tetrahydrocannabinol and lamotrigine are imminent; both will involve subjects with progressive forms of multiple sclerosis. SUMMARY: These advances mean that neuroprotection is emerging as a potentially important strategy for preventing disability in multiple sclerosis. It is likely that a range of neuroprotective strategies will be tested alone and in combination in future trials, and that trial design will be refined as experience accumulates.

Clinical Trials as Topic↗

Optic neuritis in children and its relationship to multiple sclerosis: a clinical study of 21 children.

The optic neuritis of 21 children aged between four and 14 years generally was characterized by bilateral involvement (62 per cent) and papillitis (76 per cent). Often acute infections or vaccinations were preceding events. Frequently there was pleocytosis during the disease process, with production of IgG, oligoclonal and viral antibodies, which increased during follow-up. Nine of these children (eight female) later developed multiple sclerosis, with unilateral involvement of the optic nerves and HLA Dr2 positivity. Disseminated effects on the central nervous system were similar to those of adults with multiple sclerosis. In all cases these relapses occurred within one year of the optic neuritis. EEGs did not differentiate those who developed multiple sclerosis from those who did not, but four of five patients with multiple sclerosis who were followed-up for a year or more had paroxysmal discharges, and one of the four had manifest epilepsy. Magnetic resonance imaging, visual and sensory evoked potentials and CSF studies were helpful in diagnosing multiple sclerosis. The visual prognosis was good in most cases. 17 children had no or only slight neurological disability at the end of follow-up; the other four had moderate to severe disability. This study suggests that optic neuritis is a diffuse disease, not merely affecting the optic nerves, and that the immunological events typical of multiple sclerosis can start in childhood.

Adolescent↗