¿Efecto colateral de bloqueadores beta o confusión? / Adverse effect of beta-blockers or confusion?

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Convulsions and retinal haemorrhage: should we look further?

BACKGROUND AND AIMS: The prevalence of retinal haemorrhages after convulsions is not well established. As these haemorrhages are considered characteristic of child abuse, we investigated their occurrence after convulsive episodes to see whether the finding of haemorrhage should prompt further investigation. METHODS: Prospective study of 153 children (aged 2 months to 2 years), seen in the emergency department after a convulsive episode. After a thorough history and physical examination, a retinal examination was performed by an ophthalmologist. If findings were positive, further investigation was undertaken to rule out systemic disorder or child abuse. RESULTS: One child was found with unilateral retinal haemorrhages following an episode of a simple febrile convulsion. A thorough investigation uncovered no other reason for this finding. CONCLUSION: Retinal haemorrhages following a convulsive episode are rare. Such a finding should trigger an extensive search for other reasons, including child abuse.

Total strain fields of the antero-inferior shoulder capsule under subluxation: a stereoradiogrammetric study.

The antero-inferior capsule (AIC) is the primary restraint to antero-inferior glenohumeral dislocation. This study utilizes a biomechanical model to determine the total strain field of the AIC in a subluxed shoulder. Strains were calculated from two capsule states: a nominal strain state set by inflation and a strained state set by subluxation. Marker coordinates on the AIC were reconstructed from stereoradiographs and strain fields calculated. Peak strain on the glenoid side of the AIC was significantly greater than the humeral side and strain fields were highly variable. This study reports an accurate method for measuring planar strains in a three-dimensional membrane.

Effect of schizophrenia on frontotemporal activity during word encoding and recognition: a PET cerebral blood flow study.

OBJECTIVE: Neuropsychological studies have shown that deficits in verbal episodic memory in schizophrenia occur primarily during encoding and retrieval stages of information processing. The current study used positron emission tomography to examine the effect of schizophrenia on change in cerebral blood flow (CBF) during these memory stages. METHOD: CBF was measured in 23 healthy comparison subjects and 23 patients with schizophrenia during four conditions: resting baseline, motor baseline, word encoding, and word recognition. The motor baseline was used as a reference that was subtracted from encoding and recognition conditions by using statistical parametric mapping. RESULTS: Patients' performance was similar to that of healthy comparison subjects. During word encoding, patients showed reduced activation of left prefrontal and superior temporal regions. Reduced left prefrontal activation in patients was also seen during word recognition, and additional differences were found in the left anterior cingulate, left mesial temporal lobe, and right thalamus. Although patients' performance was similar to that of healthy comparison subjects, left inferior prefrontal activation was associated with better performance only in the comparison subjects. CONCLUSIONS: Left frontotemporal activation during episodic encoding and retrieval, which is associated with better recognition in healthy people, is disrupted in schizophrenia despite relatively intact recognition performance and right prefrontal function. This may reflect impaired strategic use of semantic information to organize encoding and facilitate retrieval.

Effects of check size on visual cortex activation studied by functional magnetic resonance imaging.

We studied functional magnetic resonance imaging (fMRI) of visual cortex during checkerboard visual stimulation with three standard check sizes to examine whether activation in the visual cortex varied among these sizes. We acquired fMRI at 1.5 T in 8 normal subjects, each receiving the best refractive correction. Each subject underwent an experiment consisting of four conditions: black and white checkerboards with three check sizes (0.25-, 0.5-, and 1.0-degree) flickering at 8 Hz, and a black screen. SPM96 was used for a group data analysis with a random effects model after each of the subject's data was motion-corrected and spatially normalized to a standard brain. The activation in the visual cortex showed the greatest signal changes with the 0.5-degree check among the three check sizes. When standard check sizes are used to stimulate visual cortex in fMRI experiments, our results suggest that 0.5-degree checks flickering at 8 Hz produce the most vigorous activation in visual cortex.

Reproducibility of visual activation during checkerboard stimulation in functional magnetic resonance imaging at 4 Tesla.

PURPOSE: To investigate the reproducibility of visual activation by checkerboard stimulation, we used functional magnetic resonance imaging (fMRI) at 4 Tesla (T). METHODS: Four subjects were studied with fMRI at 4 T during checkerboard visual stimulation. The functional images were realigned and spatially normalized to the standard brain. For each subject, statistical parametric maps were made for each study, and the reproducibility was determined based on the number of supra-threshold voxels (Z > 3.5, 4.5, and 5.5). RESULTS: The mean ratio for the number of supra-threshold (Z > 4.5) voxels was 0.75, and the mean ratio for the overlapping voxels was 0.61. Restricting the region of interest within the posterior half of the brain improved reproducibility values at the low threshold (Z > 3.5), but did not improve the values at the higher thresholds. CONCLUSIONS: Despite the fact that more than half of the supra-threshold voxels were found to be active for the repeated scans, visual activation with checkerboard stimulation seems to be less reproducible than that by flash stimulation.

Visual activation in functional magnetic resonance imaging at very high field (4 Tesla).

OBJECTIVES: Functional magnetic resonance imaging (fMRI) at very high field strengths provides functional brain mapping with the enhanced signal to noise ratio and the larger blood oxygenation level-dependent (BOLD) effect. We report activated areas in the standard space detected by fMRI at 4 Tesla (T) during simple visual stimulation. MATERIALS AND METHODS: Twelve healthy young subjects were scanned using a 4 T scanner during binocular flashing visual stimulation. Functional images were realigned to the first scan and then spatially normalized. Individual and group data analyses were performed to identify areas of visual activation. RESULTS: Activation of the bilateral primary visual cortex (V1/V2) was observed along the entire calcarine fissure in all subjects. The activated area extended to the extrastriate cortex in all subjects. Activation of the bilateral lateral geniculate nucleus (LGN) was detected in all subjects. The group data showed activation of the bilateral primary visual cortex and the bilateral lateral geniculate nucleus. CONCLUSIONS: Robust activation of the vision-related areas was successfully obtained in all subjects using a 4 T magnetic resonance scanner. These results suggest that fMRI at very high field strengths may be effective in showing visual system physiology, and that it can be a promising method to assess visual function of human subjects.

Reproducibility of visual activation in functional magnetic resonance imaging at very high field strength (4 Tesla).

PURPOSE: The reproducibility of functional magnetic resonance imaging (fMRI) has been studied on 1.5 Tesla (T) (high field strength) scanners. We report the reproducibility of visual activation in fMRI at 4 T (very high field strength). METHODS: Five healthy subjects were scanned twice in the same session with a 4 T scanner during binocular flashing visual stimulation. The activated areas during the first and second acquisition were compared. RESULTS: Activation of the visual cortex was observed in all subjects and activation of lateral geniculate nucleus was also detected in four subjects. The ratio of overlapping activated voxels in the first and second acquisition was 0.81 +/- 0.05. CONCLUSIONS: Reproducibility of visual activation using fMRI at 4 T was found to be acceptable, and the results from 4T scanners show a reliability similar to those at 1.5 T.

Functional magnetic resonance imaging of lateral geniculate nucleus at 1.5 tesla.

Although activation of the lateral geniculate nucleus has been detected by functional magnetic resonance imaging with magnetic field strengths higher than 2.0 Tesla, there have been no reports of functional magnetic resonance imaging of the lateral geniculate nucleus with the more widely available 1.5 Tesla scanner. The authors used functional magnetic resonance imaging techniques at 1.5 Tesla to detect lateral geniculate nucleus activation in five of seven healthy subjects. This study shows that visual activation of the lateral geniculate nucleus can be obtained with functional magnetic resonance imaging using conventional 1.5 Tesla scanners.

Contralateral monocular dominance in anterior visual cortex confirmed by functional magnetic resonance imaging.

PURPOSE: Although it is known that the damage to anterior striate cortex results in temporal peripheral visual field loss of the contralateral eye in patients with cerebral visual disturbance, the monocularity of anterior striate cortex has not been demonstrated in normal living humans. The aim of this study was to investigate whether this could be shown noninvasively using functional magnetic resonance imaging of the human visual cortex. METHODS: Eleven normal volunteers were studied with functional magnetic resonance imaging during alternating monocular visual stimulation using a 1.5 Tesla scanner. The data were motion corrected and spatially normalized to the standard brain. The monocular activation of the visual cortex was compared with the activation by the other eye. RESULTS: In the individual data analysis, contralateral eye dominance was always observed in the anterior striate cortex. In the group analysis from 11 subjects, the area with contralateral eye dominance was found in the most anterior part of primary visual cortex where the calcarine fissure merged with the parieto-occipital sulcus. CONCLUSIONS: This study shows that the contralateral eye dominance of anterior striate cortex can be detected noninvasively with functional magnetic resonance imaging during monocular visual stimulation. The finding confirms that the anterior striate cortex, where the monocular temporal crescent is represented, is primarily monocular, but the fact that greatest density of retinal ganglion cells and photoreceptors is in the nasal hemiretina must also be taken into account when interpreting these results.

A nonsense mutation (W9X) in CRYAA causes autosomal recessive cataract in an inbred Jewish Persian family.

PURPOSE: To identify the genetic defect causing autosomal recessive cataract in two inbred families. METHODS: Linkage analysis was performed with polymorphic markers close to 14 loci previously shown to be involved in autosomal dominant congenital cataract. In one of the families a gene segregating with the disease was analyzed by single-strand conformation polymorphism (SSCP) and eventually sequenced. RESULTS: Three polymorphic markers close to the CRYAA gene located on chromosome 21q segregated with the disease phenotype in one of the families, but not in the other. Sequencing of the CRYAA in this Jewish Persian family revealed a G-to-A substitution, resulting in the formation of a premature stop codon (W9X). CONCLUSIONS: A nonsense mutation in the CRYAA gene causes autosomal recessive cataract in one family. This constitutes the first description of the molecular defect underlying nonsyndromic autosomal recessive congenital cataract. That there was no linkage to this locus in another family provides evidence for genetic heterogeneity.

Selective opiate modulation of nociceptive processing in the human brain.

Fentanyl, a mu-opioid receptor agonist, produces analgesia while leaving vibrotactile sensation intact. We used positron emission tomography (PET) to study the mechanisms mediating this specific effect in healthy, right-handed human males (ages 18-28 yr). Subjects received either painful cold (n = 11) or painless vibratory (n = 9) stimulation before and after the intravenous injection of fentanyl (1.5 microgram/kg) or placebo (saline). Compared with cool water (29 degrees C), immersion of the hand in ice water (1 degrees C) is painful and produces highly significant increases in regional cerebral blood flow (rCBF) within the contralateral second somatosensory (S2) and insular cortex, bilaterally in the thalamus and cerebellum, and medially in the cerebellar vermis. Responses just below the statistical threshold (3.5 < Z < 4.0) are seen in the contralateral anterior cingulate, ipsilateral insular cortex, and dorsal medial midbrain. The contralateral primary sensory cortex (S1) shows a trend of activation. Except for slight changes in intensity, this pattern is unchanged following a saline placebo injection. Fentanyl reduces the average visual analogue scale ratings of perceived pain intensity (47%) and unpleasantness (50%), reduces pain-related cardioacceleration, and has positive hedonic effects. After fentanyl, but not placebo, all cortical and subcortical responses to noxious cold are greatly reduced. Subtraction analysis [(innocuous water + fentanyl) - (innocuous water + no injection)] shows that fentanyl alone increases rCBF in the anterior cingulate cortex, particularly in the perigenual region. Vibration (compared with mock vibration) evokes highly significant rCBF responses in the contralateral S1 cortex in the baseline (no injection) and placebo conditions; borderline responses (3.5 < Z < 4. 0) are detected also in the contralateral thalamus. Fentanyl has no effect on the perceived intensity or unpleasantness of vibratory stimulation, which continues to activate contralateral S1. Fentanyl alone [(mock vibration + fentanyl) - (mock vibration + no injection)] again produces highly significant activation of the perigenual and mid-anterior cingulate cortex. A specific comparison of volumes of interest, developed from activation peaks in the baseline condition (no injection), shows that fentanyl strongly attenuates both the contralateral thalamic and S1 cortical responses to noxious cold stimulation (P < 0.048 and 0.007, respectively) but fails to affect significantly these responses to vibrotactile stimulation (P > 0.26 and 0.91, respectively). In addition, fentanyl, compared with placebo, produces a unique activation of the mid-anterior cingulate cortex during fentanyl analgesia, suggesting that this region of the cingulate cortex participates actively in mediating opioid analgesia. The results are consistent with a selective, fentanyl-mediated suppression of nociceptive spinothalamic transmission to the forebrain. This effect could be implemented directly at the spinal level, indirectly through cingulate corticofugal pathways, or by a combination of both mechanisms.

Hemispheric activation of anterior and inferior prefrontal cortex during verbal encoding and recognition: a PET study of healthy volunteers.

Evidence of bilateral prefrontal activation during memory encoding and retrieval has increased attention given to anatomical subdivisions within the prefrontal cortex. The current study examined anterior and inferior aspects of the prefrontal cortex to determine their degree of functional and hemispheric overlap during encoding and recognition. Cerebral blood flow of 25 healthy volunteers was measured using PET (15)O-water methods during four conditions: resting baseline, sequential finger movement, word encoding, and word recognition. Resting and motor images were averaged to provide a single reference that was subtracted from encoding and recognition using statistical parametric mapping (SPM96). Memory conditions were also subtracted from each other to identify differences in regional activity. Subjects performed well (86% correct) and had a slightly conservative response bias. Baseline subtraction from encoding revealed focal activation of left inferior prefrontal cortex (area 45) without significant contralateral activation. Recognition minus baseline subtraction produced a focal right anterior prefrontal activation (areas 9 and 10) that was not present in the left hemisphere. Bilateral effects were seen in area 45 during recognition. Subtraction of memory tasks from each other did not reveal any areas of greater activity during encoding. However, the recognition task produced greater activation in right area 9 extending into the anterior cingulate. Greater activity during recognition was also observed in left insula and bilateral visual integration areas. These results are discussed in relation to the prevailing model of prefrontal hemispheric asymmetry during episodic memory.

Reproducibility of visual activation in functional MR imaging and effects of postprocessing.

BACKGROUND AND PURPOSE: Functional MR imaging studies of the brain should be interpreted in the context of their reproducibility. We assessed the reproducibility of visual activation measured by functional MR imaging and analyzed the effect of image transformation to standard space. METHODS: Seven healthy volunteers were studied twice with echo-planner functional MR imaging at 1.5 T during visual stimulation. The studies were separated by an interval of 2 to 7 days. Functional images were analyzed after spatial normalization to the space described by Talairach and Tournoux and/or after coregistration of the images of the second study with the images of the first study. The number of active voxels for each study was determined at three thresholds. In addition, the change in the center of the mass of activation, the mean change in signal intensity, and the mean t value within the activated area were measured. These reproducibility indexes were calculated for the spatially normalized and nonnormalized data for each subject. RESULTS: Variations in visual activation were observed between the two studies in the same individual as well as across subjects. There was no evidence of an effect from image transformation on reproducibility on any of the measures. CONCLUSION: Our findings show that the reproducibility of activation in functional MR imaging may be much more variable across subjects than suggested in previous studies. The use of different types of image transformation (coregistration, spatial normalization) does not significantly affect the reproducibility of visual activation.

Prenatal diagnosis of dacryocystocele: a possible marker for syndromes.

We present our experience of the sonographic prenatal diagnosis of dacryocystocele and review the literature. This lesion can be distinguished from a facial hemangioma, dermoid or anterior encephalocele by the ultrasound findings and Doppler flow studies. These conditions are separate entities and their associated diagnosis and prognosis are very different in each case. As dacryocystocele may be part of numerous syndromes, its prenatal visualization raises the rare possibility of associated anomalies.

Neuroendocrine and psychophysiologic responses in PTSD: a symptom provocation study.

Biological research on post-traumatic stress disorder (PTSD) has focused on autonomic, sympatho-adrenal, and hypothalamo-pituitary-adrenal (HPA) axis systems. Interactions among these response modalities have not been well studied and may be illuminating. We examined subjective, autonomic, adrenergic, and HPA axis responses in a trauma-cue paradigm and explored the hypothesis that the ability of linked stress-response systems to mount integrated responses to environmental threat would produce strong correlations across systems. Seventeen veterans with PTSD, 11 veteran controls without PTSD, and 14 nonveteran controls were exposed to white noise and combat sounds on separate days. Subjective distress, heart rate, skin conductance, plasma catecholamines, ACTH, and cortisol, at baseline and in response to the auditory stimuli, were analyzed for group differences and for patterns of interrelationships. PTSD patients exhibited higher skin conductance, heart rate, plasma cortisol, and catecholamines at baseline, and exaggerated responses to combat sounds in skin conductance, heart rate, plasma epinephrine, and norepinephrine, but not ACTH. The control groups did not differ on any measure. In canonical correlation analyses, no significant correlations were found between response systems. Thus, PTSD patients showed heightened responsivity to trauma-related cues in some, but not all, response modalities. The data did not support the integrated, multisystem stress response in PTSD that had been hypothesized. Individual response differences or differing pathophysiological processes may determine which neurobiological system is affected in any given patient.

Progression of coronary artery calcification: a pilot study.

OBJECTIVE: To describe individual changes in the quantity of coronary artery calcification (CAC) measured by electron beam computed tomography (CT) and determine the rate of change in the quantity of CAC during a 3.5-year period. MATERIAL AND METHODS: Eighty-eight consecutive participants (51 men at least 30 years of age and 37 women at least 40 years of age) from a community-based CAC study were invited for a follow-up examination. Established coronary artery disease risk factors were studied at baseline. CAC score was measured by electron beam CT at baseline and follow-up. RESULTS: Of the 88 invited participants, 82 (93%) returned for a follow-up examination. Considerable variation existed among the participants in the extent of CAC score change. On average, CAC score increased over time by an estimated 24% each year (P<0.05). The relative increase in CAC score over time was significantly lower for older than for younger participants but did not vary significantly by sex. CONCLUSION: The ability to recruit follow-up participants in this pilot study and to detect significant change in CAC score over time provides evidence that electron beam CT is useful for studying progression of CAC in a sample and may be a valuable procedure for assessing the effectiveness of clinical interventions designed to retard progression of coronary atherosclerosis.

[Do our patients know the economic cost of medication of the chronic type? Are they interested?]. / Conocen nuestros pacientes el coste económico de la medicación que toman de forma crónica? Les interesa?

OBJECTIVES: To identify how much patients know about the cost of the long-term medication they take and what importance they give to its cost. DESIGN: Descriptive study with a questionnaire to people collecting their prescriptions for long-term treatment. SETTING: Patients of working age and pensioners of our health centre who take medication for chronic illnesses. PARTICIPANTS: 100 patients of working age and 100 pensioners who take medication for chronic illnesses. MEASUREMENTS: They were asked how much they thought each drug they picked up in CLT prescriptions cost. The figure given was compared with the real price. An opinion questionnaire, with 5 questions on the economic aspects of medication, was conducted. RESULTS: Patients of working age knew the price of 64% of their prescriptions with under 25% error. Pensioners only knew the cost of 27% of their prescriptions with under 25% error. 50% of patients of working age were very interested in the cost of what their doctor prescribed, whereas only 30.4% of pensioners were. CONCLUSIONS: Patients of working age know quite accurately how much the drugs they are prescribed for long-term treatment cost, but pensioners know a lot less. Patients believed that doctors were sufficiently sensitive to the cost of prescriptions.