Biomedical subjects
S Pedraza
Publications and source records attributed to S Pedraza.
[Thrombosis of the superior longitudinal sinus in patients with AIDS. A review of the literature].
Cerebral dural sinus thrombosis (CSDT) is a rare disease with a high rate of mortality. Until now it has not been well-documented in patients with the acquired immunodeficiency syndrome (AIDS). Prompt diagnosis is essential for initiation of suitable treatment, especially in cases with progressive neurological involvement. The diagnostic methods include computed tomography (CT), magnetic resonance imaging (MRI) and conventional angiography. MRI and magnetic resonance angiography (MRA) have become the methods of choice because of their sensitivity and noninvasive nature. An unusual AIDS-patient, who at the time of CSDT presentation had an associated toxoplasmosis infection is described. To our knowledge, this is the first case of CSDT diagnosed by MRI and MRA in an AIDS patient. In the follow-up, MRI and MRA showed the repermeabilitation of the sinus thrombosis. Cerebral dural sinus thrombosis should be considered as a possible cause of neurological decline in a HIV-patient with central nervous system opportunistic infection.
Women and migration: the social consequences of gender.
"This paper reviews the literature on the neglected role of women in migration. It argues that focusing on gender and the family can provide the necessary linkage of micro and macro levels of analyses. Striving to contribute to a gendered understanding of the social process of migration, the review organizes the literature along these major issues: How is gender related to the decision to migrate--i.e. what are the causes and consequences of female or male-dominated flows of migration? What are the patterns of labor market incorporation of women immigrants--i.e. what accounts for their participation in the labor force and their occupational concentration? What is the relationship of the public and the private--i.e. what is the impact of work roles on family roles and of the experience of migration on the immigrants themselves? Throughout, the necessity to understand how ethnicity, class, and gender interact in the process of migration and settlement is stressed."
[Neonatal cerebral venous thrombosis: diagnosis by magnetic resonance angiography].
Neonatal cerebral venous thrombosis (NCVT) is a rare, severe neuropathology of multiple etiology and variable clinical presentation. We describe the case of a 25-day-old infant that presented with a tonic convulsion. Ultrasound examination showed tetraventricular hemorrhage. Magnetic resonance imaging (MRI) showed the presence of acute thrombosis of the deep and superficial venous systems associated to a hemorrhagic infarct of the left thalamus. Coagulation study revealed a deficit of protein C. Thrombosis of deep cerebral veins must be ruled out as a cause of a neonatal convulsive crisis. The presence of a hemorrhagic thalamic lesion supports the diagnosis of NCVT, which must in turn be confirmed by magnetic resonance angiography (MRA).
CT of primary bilateral adrenal lymphoma.
Two cases of bilateral primary adrenal lymphoma are presented. One case had a cystic appearance and the other a homogeneous density.
[The prognostic importance of the measurement of DNA in solid tumors].
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Evolution of multiple sclerosis lesions on serial contrast-enhanced T1-weighted and magnetization-transfer MR images.
BACKGROUND AND PURPOSE: Magnetization-transfer imaging is a technique that could provide indirect evidence of the characteristics of multiple sclerosis (MS) lesions. The purpose of this work was to study the evolution of MS lesions on T1-weighted MR images over time and to investigate changes in magnetization-transfer ratio (MTR) values of MS lesions with different initial appearances on contrast-enhanced T1-weighted images. METHODS: Eleven patients with relapsing-remitting MS were studied with MR imaging. The MTRs were calculated for 47 lesions that had been classified according to their appearance on contrast-enhanced T1-weighted images. Each patient was examined at four time points over a 1-year period. The MTR changes observed in the selected lesions were compared with their initial T1-weighted appearance. RESULTS: The lowest MTR values were initially found in hypointense nonenhancing lesions and in ring-enhancing lesions, with both types showing a hypointense center. Changes in MTR values were more dynamic and reversible in ring-enhancing than in hypointense nonenhancing plaques. Nodular-enhancing lesions had slightly lower initial MTRs than did isointense non-enhancing lesions. CONCLUSION: The absence or presence of contrast uptake may indicate a different pathologic basis for hypointense MS lesions on T1-weighted MR images. These differences should be kept in mind when considering T1 lesion load as a surrogate marker of disability in MS.
[Diffusion-weighted magnetic resonance in the diagnosis of acute subcortical infarcts].
INTRODUCTION: The diagnostic efficacy of radiological studies in acute subcortical infarcts is limited by the low sensitivity of conventional computerized tomography (CT) and magnetic resonance (MR) in detecting small-sized infarcts, and the difficulty in differentiating acute from chronic lesions. Diffusion-weighted MR (DMR) has shown great sensitivity and specificity in the detection of small vessel ischemic lesions during the acute phase. OBJECTIVE: To determine the diagnostic value of DMR in the study of patients with subcortical infarcts during the acute phase. PATIENTS AND METHODS: We made a prospective analysis of 100 consecutive patients with a clinical diagnosis of subcortical infarct. In all cases MR examination was done within the first 10 days (average 3.9 days) following onset, using conventional and diffusion-weighted sequences. RESULTS: In all cases the DMR showed the presence of ischemic lesions which explained, at least partly, the clinical features of the stroke. In 42 patients (42%) the DMR gave relevant information for diagnosis, as compared with the conventional MR studies, by confirming the presence of an ischemic lesion responsible for the clinical picture. The percentage rose to 50% when the examination was done within the first two days. CONCLUSIONS: DMR gives useful information in a high percentage of patients with acute subcortical infarcts. This is due to its great sensitivity in the detection of acute lesions of small size, and capacity to distinguish acute from chronic lesions.
[Post-traumatic lesion of the carotid artery. Evaluation of the clinico-radiological diagnosis].
INTRODUCTION: Posttraumatic vascular lesions of the carotid artery (PLCA) are infrequent but have a high morbid-mortality, so early diagnosis and treatment is important. OBJECTIVE: To review the clinical and radiological findings of the PLCA with the hypothesis that there are signs which permit early diagnosis. PATIENTS AND METHODS: A retrospective study of 9 patients (p) with PLCA. RESULTS: The cause was road traffic accident (4p), fall (1p) or a single abrupt cervical movement (4p). The initial clinical feature was cervical pain (1p), deafness (1p), Claude-Bernard-Horner syndrome (4p) or symptoms of a cerebral vascular accident (6p). Cranial CT showed a cerebral infarct in the territory of the middle cerebral artery (6p), subarachnoid hemorrhage (1p) or normal (3p). Diagnosis of the vascular lesion was made using magnetic resonance (9p), arteriography (5p) and echo-Doppler (4p). The vascular lesions were: severe stenosis due to a mural thrombosis (3p), complete obstruction due to thrombosis (4p) and pseudoaneurysm (2p). CONCLUSIONS: PLCA should be suspected following craniofacial-cervical trauma when there was an abrupt neck movement, a Claude-Bernard-Horner syndrome is present or a cerebral infarct in the territory of the middle cerebral artery is shown.
Magnetization transfer ratio values and proton MR spectroscopy of normal-appearing cerebral white matter in patients with liver cirrhosis.
BACKGROUND AND PURPOSE: Hepatic encephalopathy in cirrhotic patients may be the clinical manifestation of disturbed cerebral cell volume homeostasis. The aim of this study was to investigate the presence of significant changes in magnetization transfer ratio (MTR) values, which could reflect an increase in free water within the brain of patients with liver cirrhosis, and to correlate these findings with minimal hepatic encephalopathy and proton MR spectroscopy ((1)H-MRS) abnormalities. METHODS: Twenty-four patients with liver cirrhosis and eight healthy control volunteers were included in the study. MR imaging studies included conventional T1- and T2-weighted imaging, (1)H-MRS, and magnetization transfer imaging. MTR and (1)H-MRS values were obtained from normal-appearing white matter and were correlated with each other and with the presence of minimal hepatic encephalopathy. RESULTS: (1)H-MRS showed a decrease in choline and myo-inositol and an increase in glutamine + glutamate with respect to creatine + phosphocreatine. MTR values were significantly decreased in cirrhotic patients when compared with healthy control volunteers, although this decrease was not significantly higher in the patients with minimal hepatic encephalopathy. The decreases in MTR values correlated with increases in glutamine + glutamate. CONCLUSION: The MTR decrease in patients with liver cirrhosis may be caused by low-grade astrocytic swelling produced as a response to the osmotic stress occurring in these patients. However, in this cross-sectional study, we did not find a correlation between MTR decrease and the presence of minimal hepatic encephalopathy, probably because of limitations in MTR quantification techniques.
[False negative diffusion in acute ischemic stroke].
INTRODUCTION: The new techniques of magnetic resonance imaging have produced a important advance in the early diagnosis of acute ischemic stroke. The diffusion weighted imaging (DWI) has a high sensitivity and specificity in the acute ischemia. CASE REPORT: 70 years old woman with previous history of hypertension and dyslipemia. The patient presented sudden vertigo with cervical neck pain and gaze problems. The physical exploration revealed right miosis, nistagmus, IX and X cranial nerve affection and ataxia. The clinical diagnosis was Wallenberg s syndrome and a medulla lateral infarction. However DWI was normal (10 hours). The neurological deficit was persistent and a repeated study disclosed a lateral infarction of the medulla. CONCLUSIONS: The sensitivity of DWI is reduced during the first 24 hours. There are false negative diagnosis mainly in small infarctions of posterior territory.
[Infiltration of the optic nerve by lymphoma. Diagnosis by magnetic resonance imaging].
INTRODUCTION: Systemic lymphoma with meningeal involvement is frequent and diagnosis is based on the clinical features, the study of the cerebrospinal fluid and evaluation by magnetic resonance imaging (MRI). Lymphoma with involvement of the orbitary region is more frequent in the optic nerve (ON) than of the eye itself. CLINICAL CASE: We report the case of a patient with diffuse non Hodgkin gastric lymphoma of the large B cell type, which coursed with amaurosis, exophthalmus and signs of tumorous meningeal involvement. The ophthalmologic study revealed a thrombosis in the central retinal vein. The MRI exploration only showed an infiltration of the ON with no pathological meningeal enhancement. ON involvement consisted in a peripheral enhancement of the sheath with obliteration of the subarachnoid space. This pattern accounts for the existence of an ischemic neuropathy by direct compression over the central retinal vein and artery. There are different anatomopathologic or ophthalmologic studies of neuropathy of the ON by lymphoma in the literature, but there is only one case of diagnosis by MRI. CONCLUSIONS: ON involvement can be the only radiological sign in cases of neoplastic tumours with meningeal involvement. The radiological pattern consists in a peripheral infiltration of the sheath of the ON.
[The prognostic value of computerized tomography in acute aneurysmal subarachnoid haemorrhages].
INTRODUCTION AND DEVELOPMENT: The radiological diagnosis of subarachnoid haemorrhages (SAH) is based fundamentally on studies using computerised tomography, although magnetic resonance imaging has also been proved to be highly sensitive. Spontaneous SAH is essentially due to the rupture of a cerebral aneurysm. The distribution of the SAH and the presence of associated haemorrhagic lesions are useful for developing a suspicion as to the exact whereabouts of the aneurysm causing the SAH. CONCLUSIONS: SAH is still linked to a poor prognosis despite the progress made in its diagnosis and treatment. Several radiological factors have been reported as being associated to a poorer prognosis: 1. The risk of complications is related to the extension of the SAH. The most widely accepted classification for determining the extension is the one put forward by Fisher. The higher grades III and IV are linked to a higher rate of morbidity and mortality. 2. SAH that is situated in the perimesencephalic cisterns is linked to a low risk of being of aneurysmal origin and to a good progression. 3. A size above 10 mm is linked to a poorer progression. 4. Finally, the appearance of any of the possible complications (vasospasm, rebleeding, haemorrhage, edema) is also linked to a poorer prognosis.