RESUMEN
OBJECTIVES: To assess the usefulness of serial electrophysiology in Guillain-Barré syndrome (GBS) in a multicenter setting and the reasons for change in electrodiagnostic subtypes with serial studies. METHODS: We retrospectively analysed serial electrophysiology of 51 patients with GBS from 4 European centres. Proportions of subtypes were determined at each timing. Individual case analyses were also performed where diagnostic changes occurred with either criteria, to ascertain if changes were due to disease progression or criteria inadequacy. RESULTS: At first study, comparing old vs new criteria, acute inflammatory demyelinating polyneuropathy (AIDP) was diagnosed in 70.6% vs 51%, axonal GBS in 15.7% vs 39.2%, equivocal forms in 11.8% vs 7.8%. At second study, AIDP was diagnosed in 72.5% vs 52.9%, axonal GBS in 9.8% vs 33.3%, equivocal forms in 15.7% vs 11.7%. Subtype proportions were unchanged, indicating serial studies did not, in the cohort, alter diagnostic rates for each subtype irrespective of criteria used. Individual review of cases where subtype electrodiagnosis changed indicated suboptimal specificity for AIDP/sensitivity for axonal GBS as main cause of diagnostic shifts with old criteria, whereas disease progression explained most changes with new criteria (55.6% vs 81.8%; P = .039). CONCLUSIONS: Serial electrophysiology is unhelpful in GBS. Repeat studies cannot represent the gold standard as electrodiagnosis may alter due to disease progression. Changes in electrodiagnosis relate more often to disease progression with new criteria but are more frequently due to suboptimal sensitivity/specificity with old criteria. A single electrophysiological study using the most accurate available criteria appears sufficient in GBS.
Asunto(s)
Electrodiagnóstico/métodos , Síndrome de Guillain-Barré/diagnóstico , Adulto , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Conducción Nerviosa/fisiología , Estudios RetrospectivosRESUMEN
Short-term adaptation indicates the attenuation of the functional MRI (fMRI) response during repeated task execution. It is considered to be a physiological process, but it is unknown whether short-term adaptation changes significantly in patients with brain disorders, such as multiple sclerosis (MS). In order to investigate short-term adaptation during a repeated right-hand tapping task in both controls and in patients with MS, we analyzed the fMRI data collected in a large cohort of controls and MS patients who were recruited into a multi-centre European fMRI study. Four fMRI runs were acquired for each of the 55 controls and 56 MS patients at baseline and 33 controls and 26 MS patients at 1-year follow-up. The externally cued (1 Hz) right hand tapping movement was limited to 3 cm amplitude by using at all sites (7 at baseline and 6 at follow-up) identically manufactured wooden frames. No significant differences in cerebral activation were found between sites. Furthermore, our results showed linear response adaptation (i.e. reduced activation) from run 1 to run 4 (over a 25 minute period) in the primary motor area (contralateral more than ipsilateral), in the supplementary motor area and in the primary sensory cortex, sensory-motor cortex and cerebellum, bilaterally. This linear activation decay was the same in both control and patient groups, did not change between baseline and 1-year follow-up and was not influenced by the modest disease progression observed over 1 year. These findings confirm that the short-term adaptation to a simple motor task is a physiological process which is preserved in MS.
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Adaptación Fisiológica , Encéfalo/fisiopatología , Potenciales Evocados Motores , Destreza Motora , Movimiento , Esclerosis Múltiple/fisiopatología , Análisis y Desempeño de Tareas , Adulto , Mapeo Encefálico/métodos , Femenino , Mano/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
With expanding potential clinical applications of functional magnetic resonance imaging (fMRI) it is important to test how reliable different measures of fMRI activation are between subjects and sessions and between centres. This study compared variability across 17 patients with multiple sclerosis (MS) and 22 age-matched healthy controls (HC) in 5 European centres performing an fMRI block design with hand tapping. We recruited subjects from sites using 1.5 T scanners from different manufacturers. 5 healthy volunteers also were studied at each of 4 of the centres. We found that reproducibility between runs and sessions for single individuals was consistently much greater than between individuals. There was greater run-to-run variability for MS patients than for HC. Measurements of maximum signal change (MSC) appeared to provide higher reproducibility within individuals and greater sensitivity to differences between individuals than region of interest (ROI) suprathreshold voxel counts. The variability in measurements between centres was not as great as that between individuals. Consistent with these observations, we estimated that power should not be reduced substantially with use of multi-, as opposed to single-, centre study designs with similar numbers of subjects. Multi-centre interventional studies in which fMRI is used as an outcome measure thus appear practical even when implemented in conventional clinical environments.
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Mapeo Encefálico/métodos , Ensayos Clínicos como Asunto/métodos , Potenciales Evocados Somatosensoriales , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Magnética/métodos , Esclerosis Múltiple/fisiopatología , Corteza Somatosensorial/fisiopatología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/diagnóstico , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Motor control demands coordinated excitation and inhibition across distributed brain neuronal networks. Recent work has suggested that multiple sclerosis (MS) may be associated with impairments of neuronal inhibition as part of more general progressive impairments of connectivity. Here, we report results from a prospective, multi-centre fMRI study designed to characterise the changes in patients relative to healthy controls during a simple cued hand movement task. This study was conducted at eight European sites using 1.5 Tesla scanners. Brain deactivation during right hand movement was assessed in 56 right-handed patients with relapsing-remitting or secondary progressive MS without clinically evident hand impairment and in 60 age-matched, healthy subjects. The MS patients showed reduced task-associated deactivation relative to healthy controls in the pre- and postcentral gyri of the ipsilateral hemisphere in the region functionally specialised for hand movement control. We hypothesise that this impairment of deactivation is related to deficits of transcallosal connectivity and GABAergic neurotransmission occurring with the progression of pathology in the MS patients. This study has substantially extended previous observations with a well-powered, multicentre study. The clinical significance of these deactivation changes is still uncertain, but the functional anatomy of the affected region suggests that they could contribute to impairments of motor control.
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Corteza Cerebral/fisiopatología , Cuerpo Calloso/fisiopatología , Trastornos del Movimiento/fisiopatología , Esclerosis Múltiple/fisiopatología , Red Nerviosa/fisiopatología , Inhibición Neural , Adulto , Femenino , Mano/inervación , Mano/fisiopatología , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Movimiento/fisiología , Trastornos del Movimiento/etiología , Esclerosis Múltiple/complicaciones , Músculo Esquelético/inervación , Músculo Esquelético/fisiopatología , Inhibición Neural/fisiología , Vías Nerviosas/fisiopatología , Estudios Prospectivos , Transmisión Sináptica/fisiología , Ácido gamma-Aminobutírico/deficienciaRESUMEN
We performed a prospective multi-centre study using functional magnetic resonance imaging (fMRI) to better characterize the relationships between clinical expression and brain function in patients with multiple sclerosis (MS) at eight European sites (56 MS patients and 60 age-matched, healthy controls). Patients showed greater task-related activation bilaterally in brain regions including the pre- and post-central, inferior and superior frontal, cingulate and superior temporal gyri and insula (P < 0.05, all statistics corrected for multiple comparisons). Both patients and healthy controls showed greater brain activation with increasing age in the ipsilateral pre-central and inferior frontal gyri (P < 0.05). Patients, but not controls, showed greater brain activation in the anterior cingulate gyrus and the bilateral ventral striatum (P < 0.05) with less hand dexterity. An interaction between functional activation changes in MS and age was found. This large fMRI study over a broadly selected MS patient population confirms that movement for patients demands significantly greater cognitive 'resource allocation' and suggests age-related differences in brain responses to the disease. These observations add to evidence that brain functional responses (including potentially adaptive brain plasticity) contribute to modulation of clinical expression of MS pathology and demonstrate the feasibility of a multi-site functional MRI study of MS.
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Encéfalo/fisiopatología , Cognición , Imagen por Resonancia Magnética , Movimiento , Esclerosis Múltiple/fisiopatología , Esclerosis Múltiple/psicología , Adulto , Factores de Edad , Estudios Transversales , Evaluación de la Discapacidad , Estudios de Factibilidad , Femenino , Mano/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Destreza Motora , Esclerosis Múltiple Crónica Progresiva/fisiopatología , Esclerosis Múltiple Recurrente-Remitente/fisiopatología , Factores de TiempoRESUMEN
BACKGROUND: Conflicting data have been reported on the association between interferon (IFN)-beta therapy of multiple sclerosis (MS) patients and thyroid disease development. AIMS: The goals of this study are as follows: to assess the actual occurrence of thyroid dysfunction and autoimmunity during long-term IFN-beta therapy; to establish the possible presence of predictive factors for thyroid dysfunction development and duration; and to suggest an effective follow-up protocol for patients receiving long-term IFN-beta therapy. STUDY PROTOCOL: A total of 106 MS patients (76 women) underwent IFN-beta 1a or 1b therapy for up to 84 months (median, 42 months). Thyroid function and autoimmunity were assessed at baseline and every 3-6 months throughout the treatment course. RESULTS: Baseline thyroid autoimmunity was detected in 8.5% of patients and hypothyroidism in 2.8%. Thyroid dysfunction (80% hypothyroidism, 92% subclinical, 56% transient) developed in 24% (68% with autoimmunity) of patients and autoimmunity in 22.7% (45.5% with dysfunction), without significant differences between the two cytokines; 68% of dysfunctions occurred within the first year. Autoimmunity emerged as the only predictive factor for dysfunction development (relative risk, 8.9), whereas sustained disease was significantly associated with male gender (P < 0.003). CONCLUSIONS: Both incident thyroid autoimmunity and dysfunction frequently occur in MS patients during IFN-beta therapy, particularly within the first year of treatment. Thyroid dysfunction is generally subclinical and transient in over than half of cases; preexisting or incident autoimmunity emerged as the only significant predictive factor for thyroid dysfunction development. Thyroid function and autoimmunity assessment is mandatory within the first year of IFN-beta therapy; thereafter, serum TSH measurement only in patients with thyroid disease could be sufficient.