[Functional magnetic resonance imaging: a critical analysis of its technical, statistical and theoretical implications in human neuroscience]

INTRODUCTION

The use of functional magnetic resonance imaging (fMRI) has represented an important step forward for the neurosciences. Nevertheless, it has also been subject to rather a lot of criticism.

AIM

To study the most widespread criticism against fMRI, so that researchers who are starting to use it may know the different elements that must be taken into account to be able to take a suitable approach to this technique.

DEVELOPMENT

The fact that fMRI allows brain activity to be observed makes it a very attractive and useful tool, and its use has grown exponentially since the last decade of the 20th century. At the same time, criticism against its use has become especially fierce. Most of this scepticism can be classified into aspects related with the technique and physiology, the analysis of data and their theoretical interpretation. In this study we will review the main arguments defended in each of these three areas, as well as looking at whether they are well-founded or not. Additionally, this work is also intended as a reference for novel researchers when it comes to identifying elements that must be taken into account as they approach fMRI.

CONCLUSIONS

Despite the fact that fMRI is one of the most interesting options for observing the brain available today, its correct utilisation requires a great deal of control and knowledge. Even so, today most of the criticism it receives no longer has any solid foundation on which to stand.

[Analysis of internal notices to the emergency team of the medical area at a general hospital]

OBJECTIVE

To study the frequency and characteristics of the hospitalized patients medical emergencies.

PATIENTS AND METHODS

We have collected daily the notice to the emergency room from patients hospitalized and we have analyzed the clinical and epidemiological characteristics.

RESULTS

Three hundred forty-one notices were recorded. The daily mean was higher on holidays. There were mostly medical problems (78%). Complementary explorations were performed in the 44% of the patients, and in the 77% the treatment was changed.

CONCLUSIONS

The in-patient emergencies account for an important charge of work for the emergency team and involve important diagnosis and therapeutic decisions.

[Clinical analysis of unsuspected pulmonary thromboembolism at the emergency department]

OBJECTIVES

Evaluate the degree of suspicion of pulmonary embolism (PE) in the emergency department (ED).

PATIENTS AND METHODS

We analyzed the cases of patients with TEP diagnosed during two years and compared group A (PE suspected) with group B (PE was not initially suspected).

RESULTS

57 cases of PE were admitted from ED. In 14 (25%) of them the PE was not suspected. There were statistically significant differences in the signs of deep venous thrombosis (more prevalent in group A), heart failure, and pleural effusion (more frequent in group B). The alternative diagnosis were mostly heart failure and pneumonia.

CONCLUSIONS

The patients with unsuspected PE do not have a different clinical profile. The PE is most of the times confused with heart failure and pneumonia.

Prospective study of community-acquired pneumonia of bacterial etiology in adults

The aim of this study was to prospectively analyze the bacterial etiology of community-acquired pneumonia in adults in Spain. From May 1994 to February 1996, 392 episodes of CAP diagnosed in the emergency department of a 600-bed university hospital were studied. An etiological diagnosis based on noninvasive microbiological investigations was achieved in 228 cases (58%); 173 of these diagnoses were definitive and 55 probable. Streptococcus pneumoniae, which caused 23.9% of the episodes, was the predominant pathogen observed, followed by Chlamydia pneumoniae (13.5%) and Legionella pneumophila (12.5%). Other less frequent pathogens found were Haemophilus influenzae (2.3%), Pseudomonas aeruginosa (1.5%), Mycoplasma pneumoniae (1.3%), Coxiella burnetii (1%), Moraxella catarrhalis (2 cases), Nocardia spp. (2 cases), and Staphylococcus aureus (2 cases). Streptococcus pneumoniae was significantly more frequent in patients with underlying disease and/or age > or =60 years (28% vs. 13%, P = 0.002), while Legionella pneumophila was more frequent in patients below 60 years of age and without underlying disease (20% vs. 9%, P = 0.006). Likewise, Streptococcus pneumoniae and Legionella pneumophila were the most frequent etiologies in patients requiring admission to the intensive care unit, occurring in 29% and 26.3% of the patients, respectively. In addition to Streptococcus pneumoniae, other microorganisms such as Chlamydia pneumoniae and Legionella spp. should be seriously considered in adults with community-acquired pneumonia when initiating empiric treatment or ordering rapid diagnostic tests.

[Detection of bacteremia in patients discharged from an emergency unit: study of 61 cases]

BACKGROUND

To know the prevalence, the clinical and microbiological characteristics of bacteremia episodes detected on discharged patients at the emergency unit, as well as the accordance of diagnostics and the predicting factors.

PATIENTS AND METHODS

We analysed the cases with bacteria detected on discharged patients during 2 years (1995-1996) in an university hospital. We reported: age, sex isolated organism in blood cultures, bacteremia source, leukocytes count, presence of underlying conditions, and accordance between initial and final diagnosis. We compared the characteristics of the groups with bacteremia without apparent origin and the ones with evident clinical source.

RESULTS

We detected 61 cases, the mean age was 55 years (SD = 21), and 54% were males. The most commonly isolated agent was E. coli (50%). The leukocytes count was higher 10 x 10(9)/l in 15%. The source of bacteremia was: urinary tract infection (54%) no clinical focus (31%), respiratory tract (11%) and biliary duct (3%). The 90% of urinary tract and the 71% of respiratory infections were correctly diagnosed. However only the 5% of bacteremias without apparent source was correctly diagnosed. We found these differences statistically a significant (p < 0.001 and p = 0.002). Underlying conditions were detected in the 84% of cases in bacteremia without apparently source: AIDS (22%), cirrhosis (22%), parenteral drugs addiction (17%) and venous catheter (17%). Comparing both groups, with apparent focus and without it, we found that the presence of underlying condition is the only independent factor which predispose to bacteremia (p = 0.000; RR = 4.6; IC 95% = 1.9-11.8).

CONCLUSIONS

The prevalence of bacteremia detected in discharged patients at the emergency unit seems acceptable. However those results suggest that we could decrease the number of patients with bacteremia without apparently source, because this group shows up to be the less successful in diagnosis. In patients with fever and no clinical focus in the emergency unit, it is useful to consider the presence of underlying factors to decide its management.

Comparative study of the clinical presentation of Legionella pneumonia and other community-acquired pneumonias

The aim of this study was to compare the clinical, biological, and radiologic features of presentation in the emergency ward of community-acquired pneumonia (CAP) by Legionella pneumophila (LP) and other community-acquired bacterial pneumonias to help in early diagnosis of CAP by LP. Three hundred ninety-two patients with CAP were studied prospectively in the emergency department of a 600-bed university hospital. Univariate and multivariate analyses were performed to compare epidemiologic and demographic data and clinical, analytical, and radiologic features of presentation in 48 patients with CAP by LP and 125 patients with CAP by other bacterial etiology (68 by Streptococcus pneumoniae, 41 by Chlamydia pneumoniae, 5 by Mycoplasma pneumoniae, 4 by Coxiella burnetii, 3 by Pseudomonas aeruginosa, 2 by Haemophilus influenzae, and 2 by Nocardia species. Univariate analysis showed that CAP by LP was more frequent in middle-aged, male healthy (but alcohol drinking) patients than CAP by other etiology. Moreover, the lack of response to previous beta-lactamic drugs, headache, diarrhea, severe hyponatremia, and elevation in serum creatine kinase (CK) levels on presentation were more frequent in CAP by LP, while cough, expectoration, and thoracic pain were more frequent in CAP by other bacterial etiology. However, multivariate analysis only confirmed these differences with respect to lack of underlying disease, diarrhea, and elevation in the CK level. We conclude that detailed analysis of features of presentation of CAP allows suspicion of Legionnaire's disease in the emergency department. The initiation of antibiotic treatment, including a macrolide, and the performance of rapid diagnostic techniques are mandatory in these cases.

Does IOR occur in discrimination tasks? Yes, it does, but later

When a stimulus appears in a previously cued location several hundred milliseconds after the cue, the time required to detect that stimulus is greater than when it appears in an uncued location. This increase in detection time is known as inhibition of return (IOR). It has been suggested that IOR reflects the action of a general attentional mechanism that prevents attention from returning to previously explored loci. At the same time, the robustness of IOR has been recently disputed, given several failures to obtain the effect in tasks requiring discrimination rather than detection. In a series of eight experiments, we evaluated the differences between detection and discrimination tasks with regard to IOR. We found that IOR was consistently obtained with both tasks, although the temporal parameters required to observe IOR were different in detection and discrimination tasks. In our detection task, the effect appeared after a 400-msec delay between cue and target, and was still present after 1,300 msec. In our discrimination task, the effect appeared later and disappeared sooner. The implications of these data for theoretical accounts of IOR are discussed.

Imaging resources

The concept of resources has been used in cognitive psychology to refer to computations specific to a given cognitive domain (e.g. orthographic code for words) and those general to many domains (arousal and attention). In this chapter we examine efforts to provide a picture of both kinds of resources with methods designed to explore the anatomy and circuitry of cognitive operations. We conclude that the two types of resources have separable if rather complex anatomical loci and that their common circuitry leads to interactions in which attention and arousal can influence the priority of the task specific cognitive operations. Many situations such as priming, mix the role of automatic activation of specific computations and attention to those same computations. We review some evidence from anatomical and circuit studies that indicate that the anatomy of priming relates closely to the computation involved in the task and suggest methods for separating automatic and attended influences on priming.

[Haemophilus influenzae pulmonary infection in patients infected with the human immunodeficiency virus]

BACKGROUND

Haemophilus influenzae has frequently been identified as the etiologic agent in pneumonias of patients with the human immunodeficiency virus (HIV) infection. The experience of the authors is reviewed and the significance of isolating this microorganism in respiratory samples commented upon.

METHODS

The clinical, radiological and microbiological data of patients with HIV infection in whom H. influenzae was identified in blood, lung tissue, or samples of the lower respiratory tract obtained by fibrobronchoscopy were retrospectively evaluated.

RESULTS

Twenty cases were diagnosed with 75% presenting bilateral lung infiltration. In 70% the isolation sample was that of bronchoalveolar lavage. In 40% of the total another microorganism was identified in coinfection with H. influenzae, of which Mycobacterium tuberculosis was the most frequent. Thirty-five percent of the cases presented antecedents of one or several previous pulmonary infections. H. influenzae infection was not observed with either concomitant or previous infections in 20% of the patients.

CONCLUSIONS

A high frequency of pneumonias by Haemophilus influenzae with bilateral radiologic presentation have been found. H. influenzae is frequently demonstrated as in coinfection with other agents. The role that this microorganism has in pulmonary infection of patients with HIV infection is not clearly defined.