Search PubMed⌕ Search

Biomedical subjects

S Pedraza

Publications and source records attributed to S Pedraza.

At least 19 recordsLinked to original sources
PubMed2006

Long-standing Morel-Lavallée lesion in the proximal thigh: ultrasound and MR findings with surgical and histopathological correlation.

A 65-year-old man presented with a soft mass in his proximal right thigh. Ultrasonography showed a well-defined anechoic lesion with slightly internal echoes. On MRI, the mass was hypointense and minimally hyperintense compared with muscle at T1 and hyperintense at T2, with a hypointense peripheral rim on both sequences. No signal loss was observed on T1-weighted fat-suppression MRI. The clinical setting, imaging findings and histopathological features were consistent with a long-standing Morel-Lavallée lesion.

Aged↗
PubMed2005

Comparative overview of brain perfusion imaging techniques.

Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are: Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), Xenon-enhanced Computed Tomography (XeCT), Dynamic Perfusion-computed Tomography (PCT), Magnetic Resonance Imaging Dynamic Susceptibility Contrast (DSC), Arterial Spin-Labeling (ASL), and Doppler Ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow (CBF) or volume (CBV). All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview, established by consensus among specialists of the various techniques. For clinicians, this paper should offers a clearer picture of the pros and cons of currently available brain perfusion imaging techniques, and assist them in choosing the proper method in every specific clinical setting.

Cerebrovascular Circulation↗
PubMed2004

The clinical-DWI mismatch: a new diagnostic approach to the brain tissue at risk of infarction.

OBJECTIVE: To evaluate the usefulness of a mismatch between the severity of acute clinical manifestations and the diffusion-weighted imaging (DWI) lesion in predicting early stroke outcome and infarct volume. METHODS: One hundred sixty-six patients with a hemispheric ischemic stroke of <12 hours' duration were studied. The NIH Stroke Scale (NIHSS) score and the volume of DWI lesion were measured on admission and at 72 +/- 12 hours. Infarct volume was measured on T2-weighted or fluid-attenuated inversion recovery images at day 30. Early neurologic deterioration (END) was defined as an increase of > or =4 points between the two NIHSS evaluations. Thirty-eight patients received IV thrombolysis or abciximab. Clinical-DWI mismatch (CDM) was defined as NIHSS score of > or =8 and ischemic volume on DWI of < or =25 mL on admission. The adjusted influence of CDM on END, DWI lesion enlargement at 72 hours, and infarct growth at day 30 was evaluated by logistic regression analysis and generalized linear models. RESULTS: CDM was found in 87 patients (52.4%). Patients with CDM had a higher risk of END than patients without CDM because NIHSS < 8 (odds ratio [OR], 9.0; 95% CI,1.9 to 42) or DWI lesion > 25 mL (OR, 2.0; 95% CI, 0.8 to 4.9). CDM was associated with an increase of 46 to 68 mL in the mean volume of DWI lesion enlargement and infarct growth in comparison with non-CDM. All the effects were even greater and significant in patients not treated with reperfusion therapies. CONCLUSIONS: Acute stroke patients with an NIHSS score of > or =8 and DWI volume of < or =25 mL have a higher probability of infarct growth and early neurologic deterioration. The new concept of CDM may identify patients with tissue at risk of infarction for thrombolytic or neuroprotective drugs.

Aged↗
PubMed2004

[Use of teleradiology in the evaluation and management of head-injured patients. Results of a pilot study of a link between a district general hospital and a neurosurgical referral center].

UNLABELLED: Because of the centralization of neurosurgical services, many head-injured patients who are initially evaluated in district general hospitals need to be transferred to a high technology centre for neurosurgical assessment. However, after assessment, many of these patients are sent back to the original hospital. Establishing a teleradiological system between the two hospitals would eliminate these unnecessary transfers. OBJECTIVES: 1) to describe our initial experience and the results of a pilot study of the teleradiological link between a district general hospital and a tertiary hospital for neurosurgical assessment of head-injured patients, 2) to describe the infrastructure and the technological support required for this project, 3) to analyse the effects of the teleradiological link in both centers (referring and receiving), 4) to evaluate the effectiveness of the system in avoiding unnecessary transfers, and 5) to assess its effectiveness in improving the speed and the quality of transfers in head-injured patients. MATERIAL AND METHODS: In January 1998, the Neurotraumatology Unit of Vall d'Hebron University Hospital established a teleradiological link with the General Hospital of Vic for the neurosurgical evaluation of headinjured patients. The General Hospital of Vic sent the patients' clinical information by fax. CT scan images were digitalized, compressed and prepared for transmission with the StatView program, and were then transmitted by modem to the receiving center. The duty neurosurgeon viewed the images on a PC screen using MutiView software. After evaluating this clinical and radiological information the neurosurgeon sent a report back to the referring center recommending transfer or management (admission, observation, etc.). RESULTS: We analyse the results of our experience 5 years after the implantation of the teleradiological link. CONCLUSIONS: The use of teleradiology in the daily management of head-injured patients provides clear benefits and leads to a more rational use of resources, thus significantly reduces costs. The effectiveness of the system in reducing the interval between the injury and treatment in severe cases depends more on the infrastructure of the health system in each geographical area than on sophisticated telemedicine systems. These methods should be accompanied by other measures designed to hasten the transfer of selected patients.

Adolescent↗
PubMed2003

[Neuropsychological and behavioural impairments resulting from bilateral thalamic infarct].

The neuropsychological characteristics of a patient with a bilateral thalamic infarct in the posterior communicating artery territory due to basilar artery thrombosis are described. MRI examination showed bilateral thalamic acute ischemic lesions in the zone anterior to the tuberothalamic branches. In the cognitive exploration, the patient showed verbal and visual memory disorders, impairment of the executive functions including inability to generate and make decisions and behavioural disorders including lack of inhibition, euphoria, and occasional aggressiveness. Two months later the patient had improved in the neuropsychological test scores but still suffered from severe recent memory loss, and certain behavioural disorders including lack of inhibition and euphoria. Other cases on thalamic infarcts with cognitive and behavioural impairments due to disconnection of the front subcortical pathways have been described in the literature.

Adult↗
PubMed2001

Neuropsychological outcome in relation to the traumatic coma data bank classification of computed tomography imaging.

The Traumatic Coma Data Bank (TCDB) classification of CT (computed tomography) scan has been related to the general outcome and intracranial pressure evolution. Our aim was to analyse the relationship of this classification with neuropsychological outcome and late indices of ventricular dilatation. Fifty-seven patients with a moderate or severe head injury (mean admission Glasgow Coma Scale Score, 7.7) were studied from 122 consecutive cases. There were 49 males and 8 females (mean age, 27.7 years). Subjects were classified into TCDB categories on the basis of their most serious acute CT scan finding. From the last control CT scan image, performed at a mean of 6.12 months postinjury, several measures of ventricular dilatation were calculated. Neuropsychological assessment at 6-month included tests of verbal and visual memory, visuoconstructive functions, fine motor speed, and frontal lobe functions. Patients with diffuse injury type I showed better neuropsychological outcome than patients with more severe diffuse injuries and those with mass lesions. Within the diffuse injury groups, the degree of diffuse damage was related to measures of verbal memory and attention and cognitive flexibility. Ventricular enlargement was more evident in patients with mass lesions and it decreased in the remaining groups as the severity of diffuse injury diminished. These results show that there is a relationship between acute intracranial lesion diagnosis according to TCDB classification and neuropsychological results and ventricular dilatation indices at 6 months postinjury.

Adolescent↗
PubMed2000

MRI findings in Möbius syndrome: correlation with clinical features.

The authors studied the MRI findings of three patients with Möbius syndrome. Möbius syndrome is a rare congenital disorder characterized by complete or partial facial diplegia accompanied by other cranial nerve palsies. MRI demonstrated brainstem hypoplasia with straightening of the fourth ventricle floor, indicating an absence of the facial colliculus. These MRI features suggest the diagnosis of Möbius syndrome and correlate with the clinical and neurophysiologic findings.

Adult↗
PubMed2000

Magnetic resonance anatomic study of iliocava junction and left iliac vein positions related to L5-S1 disc.

STUDY DESIGN: An in vivo anatomic study analyzing the venous anatomy in the lumbosacral area was performed. OBJECTIVES: To obtain in vivo data concerning iliocava junction and left common iliac vein positions at L5-S1. SUMMARY OF BACKGROUND DATA: The left common iliac vein and the iliocava junction are at risk during L5-S1 anterior lumbar interbody fusion. Anatomic studies have demonstrated great interindividual variability in this vascular anatomy. METHODS: Magnetic resonance angiography was used to study 134 patients. Image processing was carried out with maximum intensity projection algorithm and the maximum intensity projection and addition algorithm. Iliocava junction position was measured in the maximum intensity projection and addition image. Four groups of junction position were established: very high, high, low, and very low. The left common iliac vein position was measured in axial magnetic resonance images, and three groups were established: lateral, intermediate, and medial. To describe the operative window delimited by the venous structures at L5-S1, the study population was classified into 12 configurations by combining junction position and vein position values. RESULTS: Very high lateral included 3.76% of the patients, high lateral 48.12%, high intermediate 10.53%, high medial 0.75%, low lateral 15.04%, low intermediate 4.51%, low medial 6.77%, very low lateral 0.75%, very low intermediate 2.26%, and very low medial 7.52%. Medial vein position was significantly more frequent in men. CONCLUSIONS: In 18.05% of the study population, the venous structures overlapped the center of the L5-S1 disc, reducing the operative window.

Adolescent↗
PubMed2000

Proton magnetic resonance spectroscopy in primary and secondary progressive multiple sclerosis.

The objective of this study was to characterize and compare the proton magnetic resonance spectrum of a voxel, containing lesions or normal-appearing white matter (NAWM), in primary-progressive (PP) and secondary-progressive (SP) multiple sclerosis (MS) patients. Single-voxel proton magnetic resonance spectroscopy and magnetic resonance imaging were performed in 35 MS patients (17 PP and 18 SP) and 17 controls. Spectra from an 8 ml voxel located in the parieto-occipital region were obtained with a spin-echo pulse sequence (1600 ms/135 ms/256, TR/TE/acquisitions). Resonance areas due to N-acetylaspartate (NAA), creatine/phosphocreatine (Cr) and choline compounds (Cho) were determined, and results expressed in terms of area in arbitrary units or as metabolite ratios. With respect to the control group, there were significant reductions in NAA and NAA/Cho ratio in the PP-lesion, SP-lesion, PP-NAWM and SP-NAWM groups. There were no significant differences between the PP-NAWM and SP-NAWM groups. These results support the existence of metabolic changes in the white matter of PP and SP patients and suggest that there is neuronal damage and/or loss in both clinical courses. Finally, characterization of the parieto-occipital region showed no significant differences in the spectral pattern of NAWM between PP and SP clinical courses of MS.

Adult↗
PubMed2000

Does an increase in cerebral perfusion pressure always mean a better oxygenated brain? A study in head-injured patients.

The adequate management of cerebral perfusion pressure (CPP) continues to be a controversial issue in head-injured patients. The purpose of our study was to test two hypotheses. The first was that in patients with a CPP below 70 mm Hg, oxygen delivery is compromised and that therefore signs of tissue hypoxia would be reflected in low PtiO2 measurements. The second hypothesis was that manipulating mean arterial blood pressure to increase CPP improves oxygen delivery, particularly in patients with a CPP below 70 mm Hg. Twenty-five moderately or severely head-injured patients were included in the study. In all of them PtiO2 was monitored in the non-injured hemisphere using the Licox system (GMS, Kiel-Mielkendorf, Germany). Arterial hypertension was induced with phenylephrine 29 times. To quantify the effect of increasing mean arterial blood pressure (MABP) on oxygen delivery to the brain, the PtiO2-BP index was calculated (PtiO2-BP index = delta PtiO2/delta MABP). In 16 tests (55%) baseline CPP was above or equal to 70 mm Hg and in the remaining 13 (45%) it was below 70 mm Hg. Mean increase in MABP after phenylephrine was 23.7 +/- 10.2 mm Hg. Mean PtiO2 was 29.5 +/- 14.7 mm Hg in patients with a basal CPP of below 70 mm Hg and 28.9 +/- 10.6 mm Hg in patients in the high CPP group. These differences being not statistically significant. The PtiO2-BP index was 0.29 +/- 0.23 in patients with a basal CPP of below 70 mm Hg and in patients with a CPP of above 70 mm Hg this index was 0.16 +/- 0.11 Hg. These differences were not statistically significant (Student's t-test, P = 0.09). In our study a low PtiO2 was not observed in patients with marginally low CPPs (48-70 mm Hg) and readings below 15 mm Hg were observed in cases with both normal or supranormal CPPs. We conclude that episodes of low PtiO2 could not be predicted on the basis of CPP alone. On the other hand, raising CPP did not increase oxygen availability in the majority of cases, even if the CPP was markedly improved.

Adolescent↗
PubMed2000

Cerebral hemodynamic effects of 7.2% hypertonic saline in patients with head injury and raised intracranial pressure.

The aim of the present study was to investigate the acute effects of 7.2% hypertonic saline (HS) on intracranial pressure (ICP), cerebral and systemic hemodynamics, serum sodium, and osmolality in 14 patients with moderate and severe traumatic brain injury (Glasgow Coma Scale < or =13) and raised ICP (>15 mm Hg) within the first 72 h postinjury. After CO2 reactivity and autoregulation were tested, each patient received a 15-min infusion of 7.2% HS (1,232 mEq/L, volume 1.5 mL/kg). ICP, serial hemodynamics, cerebral blood flow (CBF) estimated from cerebral arteriovenous oxygen content difference (AVDO2), and laboratory variables, including serum osmolality, electrolytes, urea, and creatinine were collected before infusion (T0) and at 5, 30, 60, and 120 min after (T5, T30, T60, T120). Urine output was measured 2 h before infusion and at T120. While CO2 reactivity was preserved in all patients, autoregulation was preserved in only four. ICP decreased to about 30% of base line (p = 0.0001) during the whole study period. During the first hour after infusion, cerebral perfusion pressure (p< or =0.04) and cardiac index (CI; p< or =0.01) increased, while systemic vascular resistance index fell (p< or =0.05). Heart rate increased (p< or =0.04) during the first 30 min. Pulmonary artery occlusion pressure (PAOP) increased (p = 0.004) at T5. There were no significant changes in mean arterial blood pressure (MABP), urine output, and estimated CBF. A significant positive correlation (r = 0.75; p = 0.02) between ICP and serum osmolality was found at T5. The administration of 7.2% HS in patients with traumatic brain injury significantly reduces ICP without significant changes in relative global CBF (expressed as 1/AVDO2), increases CI and transiently increases PAOP, without changing MABP and urine output. The correlation between changes in osmolality and ICP supports the hypothesis that HSS may in part decrease ICP by means of an osmotic mechanism.

Adult↗
PubMed1999

Spontaneous ventriculostomy: report of three cases revealed by flow-sensitive phase-contrast cine MR imaging.

Spontaneous ventriculostomy is a rare condition that occurs with the spontaneous rupture of a ventricle, resulting in a communication between the ventricular system and the subarachnoid space. Three cases of spontaneous ventriculostomy through the floor of the third ventricle that occurred in cases of chronic obstructive hydrocephalus are presented. The communication was identified via flow-sensitive phase-contrast cine MR imaging. Spontaneous ventriculostomy is probably a result of a rupture of the normally thin membrane that forms the floor of the third ventricle and, with long-standing obstructive hydrocephalus, creates an internal drainage pathway that spontaneously compensates for the hydrocephalus.

Adolescent↗
PubMed1999

Radiologic findings in two cases of acute Schmörl's nodes.

We describe two cases of atypical acute Schmörl's nodes, one benign, the other on a tumoral vertebra. In both cases, MR imaging showed a decreased vertebral T1 signal and a slightly increased T2 signal. These signal intensities are indistinguishable from tumoral disease or inflammatory lesions. The identification of endplate defects or intranuclear cleft bending of the disk by either CT or MR may be helpful for the correct diagnosis of acute Schmörl's nodes.

Adult↗
PubMed1998

Effects on intracranial pressure of fentanyl in severe head injured patients.

Despite opioids are routinely used for analgesia in head injured patients, the effects of such drugs on ICP and cerebral hemodynamics remain controversial. Cerebrovascular autoregulation (CAR) could be an important factor in the ICP increases reported after opioid administration. In order to describe the effects on intracranial pressure of fentanyl and correlated such effects with autoregulation status, we studied 30 consecutive severe head injury patients who received fentanyl (2 micrograms/kg) intravenously over one minute. Prior to study, CAR was assessed. Monitoring included MAP, HR, SaO2, ETCO2, SjO2 and ICP. Changes in cerebral blood flow (CBF) were estimated from relative changes in AVDO2. Patients mean GCS was 5.7 +/- 1.7 (mean +/- STD) and mean ICP on admission was 23.8 +/- 16.3 mmHg. Fentanyl caused significant increases in ICP and decreases in MAP and CPP, but CBF remained unchanged when estimated by AVDO2. In patients with preserved CAR (34.5%), opioid-induced ICP increase was greater (but not statistically significant) than in those with impaired CAR (65.5%). We conclude than fentanyl moderately increased ICP and decreased MAP and CPP. Our data suggests that in patients with preserved CAR, potent opioids could cause greater increases of ICP, probably due to activation of the vasodilatadory cascade.

Adolescent↗
PubMed1998

Evaluation of cerebrovascular CO2-reactivity and autoregulation in patients with post-traumatic diffuse brain swelling (diffuse injury III).

The present study was undertaken to elucidate the status of autoregulation and CO2-reactivity soon after injury in patients with a post-traumatic diffuse bilateral brain swelling. A prospective study was carried out in 31 consecutively admitted patients with a severe head injury and a Diffuse Brain Injury type III, following the definition stated by the Traumatic Coma Data Bank classification. To evaluate CO2-reactivity, AVDO2 was measured before and after ventilator manipulations. Assuming a constant CMRO2 during the test, changes in 1/AVDO2 reflect changes in CBF. Patients with changes in estimated CBF below or equal to 1% were included in the impaired/abolished CO2-reactivity group. To test autoregulation, hypertension was induced using phenylephrine. Arterial and jugular blood samples were taken to calculate AVDO2 before and after a steady state of MABP was obtained. Cerebrovascular response to CO2 was globally preserved in all but two cases (6.5%). In contrast, autoregulation was globally preserved in 10 (32.3%) and impaired/abolished in 21 cases (67.7%). Our data do not support the premise that increasing cerebral perfusion pressure by inducing arterial hypertension is beneficial in those patients with a diffuse brain swelling in whom autoregulation is impaired or abolished. Clinical implications for treatment are discussed.

Adult↗
PubMed1998

Incidence of intracranial hypertension after severe head injury: a prospective study using the Traumatic Coma Data Bank classification.

UNLABELLED: Intracranial hypertension (ICH) is a frequent finding in patients with a severe head injury. High intracranial pressure (ICP) has been associated with certain computerized tomography (CT) abnormalities. The classification proposed by Marshall et al. based on CT scan findings, uses the status of the mesencephalic cisterns, the degree of midline shift, and the presence or absence of focal lesions to categorize the patients into different prognostic groups. Our aim in this study was to analyze the ICP evolution pattern in the different groups of lesions of this classification. PATIENTS AND METHODS: We present the results of a prospective study in 94 patients with severe head injury, in whom ICP was monitored for at least 6 hours. ICP evolution was classified into three different categories: 1) ICP always < 20 mm Hg, 2) Intracranial hypertension at some time during monitoring, but controlled by medical or surgical treatment, 3) Uncontrollable ICP. The ICP pattern was correlated with the final CT diagnostic category. CONCLUSIONS: 3 patients had a normal CT scan, and none of them presented intracranial hypertension. In diffuse injury type II, the ICP evolution may be quite different. Patients with bilateral brain swelling (Diffuse Injury III) have a high risk of increased ICP (63.2%). Although in our study the frequency of Diffuse Injury IV was low, all patients in this category had a refractory ICP. In the category of evacuated mass lesions, two thirds of the patients presented an intracranial hypertension. In one third, ICP was refractory to treatment. 85% of patients with a non-evacuated mass lesion showed an increased ICP.

Adult↗