Resonancia magnética funcional de la corteza visual: estudio de las relaciones entre la intensidad del estímulo y la respuesta BOLD / Functional magnetic resonante imaging of the visual cortex relation between stimulus intensity and bold response

Introducción. La investigación sobre la visión ocupa un lugar central en neurociencia. Nuevas técnicas de neuroimagen, como la resonancia magnética funcional (RMf), permiten aumentar el conocimiento sobre el funcionamiento del sistema visual rápidamente y de forma no invasiva. El presente estudio examina el efecto de pequeños cambios en la intensidad de un estímulo sobre la respuesta de la corteza visual. Objetivos. Analizar la reacción de la corteza visual ante diferentes intensidades de una fuente luminosa, y examinar las posibles diferencias en la respuesta BOLD entre controles y sujetos con fotofobia. Sujetos y métodos. Se realizo una RMf (3 T) a 20 controles y a 20 sujetos con fotofobia, durante la estimulación visual con diferentes intensidades de luz. Se cuantificó la respuesta BOLD, tanto el área como a la intensidad del cambio de señal, en el córtex occipital. Resultados. Se encontró una relación directa entre la intensidad de los estímulos y la respuesta de la corteza occipital, con cambios significativos en el área de activación y con tendencia similar (aunque no significativa) en la intensidad de la respuesta BOLD. Además, la respuesta cortical es más pronunciada en sujetos con fotofobia, sobre todo en intensidades bajas e intermedias. Conclusiones. La RMf se muestra como una técnica válida y robusta para el registro de respuestas consistentes y reproducibles entre distintos sujetos y grupos, tanto para el estudio del funcionamiento normal de la corteza occipital como en casos de respuesta anómala, lo que abre la posibilidad de utilizarla en estudios clínicos

Introduction. Visual system is a high interest topic in neuroscience research. The new neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), allow us to quickly improve our knowledge on the visual system using non-invasive methods. This work examines the effect of small changes in the intensity of a visual stimulus over the BOLD response in the visual cortex. Aims. To perform a detailed analysis of the visual cortex reaction to different intensities of a light source and to verify the ties between the intensity of the visual stimulus and the cortical response. Subjects and methods. Using fMRI (3 T), we registered BOLD response (area and intensity of the signal change) in 20 photophobic patients and 20 controls while viewing different stimulus intensities from a light source. Results. We found a direct relation between stimulus intensity and occipital response. We show that cortical reactivity is higher in patients with photophobia than normal controls, specially for the lower and medium intensities. Conclusions. fMRI is a valid and robust technique to register consistent and reproducible responses in different groups of subjects. It is useful for the study of normal cortex functioning as well as for clinical use

[Functional magnetic resonance imaging of the visual cortex: relation between stimulus intensity and bold response]. / Resonancia magnética funcional de la corteza visual: estudio de las relaciones entre la intensidad del estímulo y la respuesta BOLD.

INTRODUCTION: Visual system is a high interest topic in neuroscience research. The new neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), allow us to quickly improve our knowledge on the visual system using non-invasive methods. This work examines the effect of small changes in the intensity of a visual stimulus over the BOLD response in the visual cortex. AIMS: To perform a detailed analysis of the visual cortex reaction to different intensities of a light source and to verify the ties between the intensity of the visual stimulus and the cortical response. SUBJECTS AND METHODS: Using fMRI (3 T), we registered BOLD response (area and intensity of the signal change) in 20 photophobic patients and 20 controls while viewing different stimulus intensities from a light source. RESULTS: We found a direct relation between stimulus intensity and occipital response. We show that cortical reactivity is higher in patients with photophobia than normal controls, specially for the lower and medium intensities. CONCLUSIONS: fMRI is a valid and robust technique to register consistent and reproducible responses in different groups of subjects. It is useful for the study of normal cortex functioning as well as for clinical use.

The influence of extreme body weight on clinical outcome of patients with venous thromboembolism: findings from a prospective registry (RIETE).

BACKGROUND: Data evaluating the safety of using weight-based dosing of low-molecular-weight heparin (LMWH) in either underweight or obese patients with venous thromboembolism (VTE) are limited. Thus, recommendations based on evidence from clinical trials might not be suitable for patients with extreme body weight. PATIENTS AND METHODS: Patients with objectively confirmed, symptomatic acute VTE are consecutively enrolled into the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) registry. For this analysis, data from patients in the following ranges of body weight were examined: <50, 50-100, and >100 kg. Patient characteristics, underlying conditions, treatment schedules and clinical outcomes during the first 15 days of treatment were compared. RESULTS: As of August 2004, 8845 patients with acute VTE were enrolled from 94 participating centers. Of these, 169 (1.9%) weighed <50 kg, 8382 (95%) weighed 50-100 kg and 294 (3.3%) weighed >100 kg. Patients weighing <50 kg were more commonly females, were taking non-steriodal antiinflammatory drugs (NSAIDs), and had severe underlying diseases more often than patients weighing 50-100 kg. Their incidence of overall bleeding complications was significantly higher than in patients weighing 50-100 kg (odds ratio 2.2; 95% CI: 1.2-4.0). Patients weighing >100 kg were younger, most commonly males, and had cancer less often than those weighing 50-100 kg. Incidences of recurrent VTE, fatal pulmonary embolism or major bleeding complications were similar in both groups. CONCLUSIONS: Patients with VTE weighing <50 kg have a significantly higher rate of bleeding complications. The clinical outcome of patients weighing over 100 kg was not significantly different from that in patients weighing 50-100 kg.

[Clinical and analytical findings in patients with toxic oil syndrome. Study of a cohort of 758 patients]. / Hallazgos clínicos y analíticos en pacientes afectados por el síndrome del aceite tóxico. Estudio de una cohorte de 758 pacientes.

OBJECTIVE: To report the symptoms and analytical findings observed in the collective of patients affected with the toxic oil syndrome (TOS) 18 years after the poisoning. METHODS: At the Centro de Investigación sobre el Síndrome del Aceite Tóxico (CISAT) we followed the clinical and analytical course of 758 patients affected with the TOS since December 1997 up to May 1999. Patients were evaluated by means of a previously standardized questionnaire in which a clinical review and a battery of complementary tests (thyroid hormones, spirometry with diffusion test and arterial gasometry) were included. One hundred and sixty-two patients underwent also echocardiogram because of presumptive pulmonary hypertension and/or heart disease. RESULTS: Out of the 758 patients, 516 were females and 242 males (M:F ratio 2:1), with ages ranging from 17 to 84 years (mean age 47 years). One of the most remarkable findings was the increased prevalence of cardiovascular risk factors: arterial hypertension (34%), dyslipemias (44%), overweight (40%), obesity (27%), carbohydrate intolerance (9%) and diabetes mellitus (9.4%). The most common reported symptoms were: cramps (78%), arthralgias (78%), and paresthesias (70%). Only 2.8% of patients reported to be asymptomatic. The analytical results most commonly changed were: changes in lipidic and carbohydrate metabolism (already reported), overt or subclinical hypothyroidism (6.6%) and respiratory changes in patients with no previous pulmonary disease: changes in spirometry (6%), diffusion test (8%) and hypoxemia (18%). Echocardiographic findings suggestive of PHT were obtained in 3.1% of cases. CONCLUSIONS: Although TOS occurred in 1981, this syndrome still has a relevant morbidity in a portion of the spanish population. To remark the high prevalence of cardiovascular risk factors with changes in lipidic and carbohydrate metabolism and subclinical hypothyroidism observed in our series. Further studies are necessary to evaluate the actual dimension of this poisoning.

Hallazgos clínicos y analíticos en pacientes afectados por el síndrome del aceite tóxico. estudio de una cohorte de 758 pacientes / Clinical and analytical findings in patients affected with the toxic oil syndrome. Study of a cohort of 758 patients

Objetivo. Describir la sintomatología y los hallazgos analíticos que el colectivo de pacientes afectados por el síndrome del aceite tóxico (SAT) presenta 18 años después de haber sufrido la intoxicación. Métodos. En el centro de Investigación sobre el Síndrome del Aceite Tóxico (CISAT) hemos seguido la evolución clínica y analítica de 758 pacientes afectados por el SAT desde diciembre de 1997 hasta mayo de 1999. Los pacientes fueron evaluados mediante un cuestionario previamente estandarizado en el que se incluía una revisión clínica y una batería de exploraciones complementarias, entre las que se incluían hormonas tiroideas, espirometría con prueba de difusión y gasometría arterial. A 162 pacientes se les realizó además ecocardiograma por presentar sospecha de hipertensión pulmonar y/o cardiopatía. Resultados. De los 758 pacientes, 516 eran mujeres y 242 varones (M:V-2:1), con edades comprendidas entre 17 y 84 años (edad media de 47 ñ años). Uno de los hallazgos más llamativos fue la elevada prevalencia de los factores de riesgo cardiovasculares: hipertensión arterial (34 por ciento), dislipidemias (44 por ciento), sobrepeso (40 por ciento), obesidad (27 por ciento), intolerancia hidrocarbonada (9 por ciento) y diabetes mellitus (9,4 por ciento). Los síntomas más frecuentemente referidos fueron: calambres (78 por ciento), artralgias (78 por ciento) y parestesias (70 por ciento). Únicamente referían estar asintomáticos el 2,8 por ciento de los afectados. Los resultados analíticos alterados con más frecuencia fueron: alteraciones del metabolismo lipídico e hidrocarbonado (ya referidos), hipotiroidismo franco o subclínico (6,6 por ciento) y alteraciones respiratorias en pacientes sin patología pulmonar previa conocida: alteraciones en la espirometría (6 por ciento), en la prueba de difusión (8 por ciento) e hipoxemia (18 por ciento). Se obtuvieron datos ecocardiográficos sugestivos de hipertensión pulmonar (HTP) en el 3,1 por ciento de los casos. Conclusiones. A pesar de que el SAT ocurrió en 1981, este síndrome sigue teniendo una importante morbilidad en parte de la población española, destacando la elevada prevalencia de factores de riesgo cardiovascular con alteraciones del metabolismo lipídico e hidrocarbonado e hipotiroidismo subclínico encontrados en nuestra serie. Son necesarios estudios ulteriores para evaluar la dimensión definitiva de esta epidemia (AU)

[Superior vena cava syndrome: a study based on 81 cases]. / Síndrome de vena cava superior: análisis de una serie de 81 casos.

BACKGROUND: Characterize the etiology, clinical picture, radiographic findings, usefulness of several diagnostic studies in establishing an etiologic diagnosis, and outcome after treatment of superior vena cava syndrome (SVCS). METHODS: We reviewed the charts of all patients diagnosed of SVCS in our hospital between the years 1983 and 1996. RESULTS: Eighty-one patients (70 male, 11 female) with an average age of 61 years were included in the study. In 77 (95%) patients a neoplastic cause was diagnosed, mainly lung cancer (76%). The most common clinical findings were: feeling of fullness in the head (81%), edema of the face and arms (78%), jugular venous distention (75%), prominent venous pattern over the chest wall (73%), dyspnea (59%), and cough (37%). The average length of time from the onset of symptoms to the date of diagnosis was 28 days. The chest x-ray was abnormal in 78 (96%) cases: mediastinal widening (51%) and right hilar mass (48%) were the most common findings. The diagnosis of SVCS was evident (from clinical picture and chest roentgenogram) in 76 (94%) patients. In SVCS due to malignancy, the most productive investigations in establishing a pathologic diagnosis were bronchoscopy (54%) and biopsy of a superficial lymph node (18%). Partial or complete clinical response to treatment was achieved in seventy percent of the cases. CONCLUSIONS: SVCS is an uncommon entity and his most frequent cause is bronchogenic carcinoma. The characteristic clinical and radiographic findings allow to do a reliable diagnosis of the syndrome. Initially, clinical response (partial or complete) to treatment is achieved in most patients.