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Biomedical subjects

T Segura

Publications and source records attributed to T Segura.

At least 19 recordsLinked to original sources
PubMed2005

[Brain haemodynamics in obstructive sleep apnea syndrome].

The obstructive sleep apnea syndrome (OSAS) is associated to a increased risk of cardiovascular diseases, including stroke. However, it is not known the cause of this last association. In this work the authors carry out a brief review of the theories that explain the relationship between OSAS and stroke and comment the potential alterations in cerebral hemodynamics of sleep apnea syndrome patients. The results of a recent case control study show that there are relevant differences in cerebral blood flow between OSAS patients and healthy subjects even in wakefulness. This fact could help to explain why OSAS causes a higher risk for suffering ischaemic strokes.

Cerebrovascular Circulation↗
PubMed2005

[Thrombolytic treatment in stroke in patients with intracardiac thrombus: presentation of one case].

Intravenous tissue plasminogen activator (t-PA) is a recent proven effective treatment for acute ischemic stroke patients. However, the use of t-PA in some special settings is controversial. One of these is the presence of a cardiac thrombus, given that the use of t-PA could potentially accelerate breakup of the thrombus and cause additional embolisms. The authors describe the case of a cardiological patient with a cardiac thrombus who was given IV t-PA for acute stroke treatment without complications. We discuss the necessity or not of a 24 hours delay before anticoagulants administration in these special patients.

Brain Infarction↗
PubMed2002

[Prolonged clinical pattern of brain death in patients under barbiturate sedation: usefulness of transcranial Doppler].

INTRODUCTION: Throughout the world, is fully accepted that a person is dead when brain death exists. In most situations, neurological criteria permit the diagnosis of brain death, but in some instances, as when high-dose barbiturate therapy has been used, confirmatory testing are required by law. CLINICAL CASE: We report the case of a 17 year-old women who suffered high-dose barbiturate therapy due to post traumatic intracranial hypertension. During the period of the barbiturate infusion and until six days after the suppression of this therapy, neurological exploration and EEG findings seem to confirm brain death, while transcranial Doppler (TCD) study remained normal. CONCLUSIONS: TCD is a fast, simple and accurate confirmatory testing in the determination of brain death and its findings are not affected by high-dose barbiturate therapy. We think that TCD must be present in all hospitals where mechanical ventilation and support of patients are carried out.

Adolescent↗
PubMed2001

Embolism in acute middle cerebral artery stenosis.

OBJECTIVE: To investigate the frequency of middle cerebral artery (MCA) stenosis in a series of nonselected patients and the coexistence of microembolic signals with stenosis. METHODS: MCA stenosis was sought by transcranial Doppler (TCD) in 387 patients admitted consecutively with acute ischemic cerebrovascular disease within the first 48 hours of the onset of symptoms and again at 6 months. TCD monitoring for microembolic signals was performed on all patients with MCA stenosis. RESULTS: MCA stenoses were found in 29 patients (7%), although in only 20 patients (5%) was the stenosis symptomatic. Microembolic signals were detected in five of 14 symptomatic stenoses (36%) monitored at the acute phase, but none were found in the chronic phase or in asymptomatic stenosis. Despite one third of symptomatic patients having had a further source of emboli, microembolic signals were detected only distally to the MCA stenosis. In the symptomatic group, 25% of stenoses had completely disappeared 6 months after stroke. Microembolic signal detection at the acute phase was associated with the subsequent disappearance of the stenosis. CONCLUSIONS: The frequency of symptomatic MCA stenosis in acute ischemic stroke was 5% in the population studied. Many stenoses are transient, and microembolic signals are often detectable at the poststenotic segment in the acute phase. The origin of at least 25% of symptomatic acute MCA stenoses may be embolic rather than atherosclerotic.

Adult↗
PubMed2001

Neuropathological findings in a patient with epilepsy and the Parry-Romberg syndrome.

PURPOSE: The Parry-Romberg syndrome is an unusual disorder frequently associated with epilepsy. The origin of this disease, and the cause of epilepsy, are unknown. This study is the first reported case of the Parry-Romberg syndrome, with intractable temporal lobe epilepsy, in which detailed microanatomic analyses have been performed on resected brain tissue obtained after surgical intervention. METHODS: Standard histopathologic methods and correlative light and electron microscopy, combined with immunocytochemical techniques, were used to study in detail the synaptic microorganization of the resected hippocampal formation. RESULTS: After surgery, the patient was seizure free (follow-up period of 4 years and 7 months). The resected temporal lobe showed a variety of dramatic microanatomic alterations (small groups of ectopic cells, neuronal loss, gliosis, and activated microglial cells) in mesial structures, including the entorhinal cortex, subiculum, and dentate gyrus. At the electron-microscopic level, we found that in the dentate gyrus, the number of synapses in the cell-sparse region adjacent to the ectopic mass of neurons was almost twice that found in the molecular and polymorph cell layers, indicating the intrusion of neuritic processes and synapse formation. In addition, the symmetrical axosomatic synapses characteristically found on granule cells, which are likely derived from gamma-aminobutyric acid (GABA)ergic inhibitory basket cells, were not observed. CONCLUSION: The complete seizure relief after surgery suggests that the pacemaker region(s) of seizure activity were within the resected tissue. However, we do not know which of the multiple neuropathologic findings reported here were the primary cause of seizure activity. Nevertheless, the changes found in the dentate gyrus circuitry appear to be among the most important alterations that would lead to epilepsy.

Adult↗
PubMed2001

Atherosclerotic aortic arch plaques in cryptogenic stroke: a microembolic signal monitoring study.

BACKGROUND AND PURPOSE: To find out the prevalence of relevant atherosclerotic plaques in the aortic arch and their potential role as a source of embolism in cryptogenic stroke. METHODS: We performed a transoesophageal echocardiography (TEE) on 49 patients with cryptogenic stroke from a total series of 212 non-selected patients with acute ischaemic stroke studied prospectively by cranial computed tomography (CT), colour-duplex and transcranial Doppler (TCD) sonography with micro-embolic signal (MES) monitoring. Cryptogenic stroke was diagnosed in those patients without carotid or intracranial stenosis > 50%, nor lacunar or cardio-embolic strokes. We defined relevant plaques as those > or = 4 mm thick located in the ascending aorta or proximal arch. RESULTS: Twenty-three patients (46.9%) had atherosclerotic aortic plaques (AAP): 3 in the ascending aorta (in 1 > or = 4 mm), 11 in the proximal aortic arch (in 4 > or = 4 mm) and 9 in the descending aorta (in 5 > or = 4 mm). Hence, 5 patients (10.2%) had relevant plaques. Aortic plaques were significantly related to older age (p < 0.001) and male gender (p = 0.042). A carotid artery stenosis < 50% was found in 39% of patients with AAP and in 8% of those without AAP (p = 0.009). MES were detected in 3 patients with plaques > or = 4 mm thick, but not in those without AAP or with AAP < 4 mm thick (p = 0.006). CONCLUSION: Although few patients with cryptogenic stroke had relevant plaques in our non-selected population, our results support the hypothesis that relevant aortic plaques have embolic potential.

Aged↗
PubMed2000

Cerebral embolism in a patient with polycythemia rubra vera.

Polycythemia rubra vera (PRV) is a rare haematological disorder that has a high risk of stroke, although the pathophysiological origin of the cerebral ischaemia in this disease is not well known. We report a case of a stroke patient with PRV in whom bilateral embolic signals were detected by transcranial Doppler (TCD). Cerebral computed tomography showed a cortical middle cerebral artery infarction, echocardiography was normal, duplex-scan showed moderate left carotid stenosis and digital angiography disclosed right siphon stenosis. TCD examinations in the acute phase repeatedly showed a great number of bilateral microembolic signals (MESs). Four months later magnetic resonance angiography showed no flow signal in the right siphon and a severe stenosis of the proximal right MCA. The detection of bilateral MESs in the absence of cardiac sources of embolism observed in this patient suggests that ischaemic cerebral events in PRV may have an embolic origin favoured by a prothrombotic state.

Aged↗
PubMed1999

[Normal values for transcranial doppler studies in our medium].

OBJECTIVE: Transcranial Doppler is a technique which is being used ever more frequently in the study of intracranial arteries and is very useful in the study of cerebrovascular disease. The typical values of a healthy population in our country are unknown. The aim of this study was determine mean velocity and pulsatility index reference values in a healthy population. PATIENTS AND METHOD: Transcranial Doppler basal examination was carried out on 118 healthy volunteers without prior haematological or cerebrovascular conditions. Those found to have extracranial arterial stenoses were excluded as were those in whom bilateral temporal bone hyperostosis did not permit insonation in either middle cerebral arteries. The nine intracranial arteries were sounded systematically at fixed depths. The mean and standard deviations of each variable were calculated for side, age group and sex. RESULTS: 49% were males and average age was of 56 years (range, 21-87 years). A sufficient signal to determine the parameters of the study was obtained in 89% of middle cerebral arteries. Statistically significant differences in mean velocity and pulsatility index were found between age groups and sexes. CONCLUSIONS: Sex and age must be taken into account in establishing typical patterns in transcranial Doppler examination. Our results enable parameters of typical values to be established for the adult population in Spain.

Adult↗
PubMed1998

Clusters of microembolic signals: a new form of cerebral microembolism presentation in a patient with middle cerebral artery stenosis.

BACKGROUND: Middle cerebral artery (MCA) stenosis is a rare occlusive disease in western populations, with a high risk of stroke recurrence. An artery-to-artery embolic mechanism has been argued. We report the detection of a new pattern of microembolic signals (MES) in the MCA poststenotic segment in a patient with multiple recurrent transient ischemic attacks. CASE DESCRIPTION: A 75-year-old man was admitted to our hospital with a transient leg monoparesis on the left side. Right MCA stenosis was detected by transcranial Doppler ultrasonography (TCD). In spite of aspirin treatment, the patient had a recurrent right hemispheric transient ischemic attack, and anticoagulant therapy was started. A new, similar event happened after correct anticoagulation. The bigated TCD monitoring study of both MCAs disclosed clusters of MES at the poststenotic MCA segment. Each cluster contained between 12 and 45 embolic signals. The patient became asymptomatic and clusters of MES disappeared, coinciding with the combination of ticlopidine and oral anticoagulants. CONCLUSIONS: We describe a new presentation of MES, ie, grouped in clusters of signals, that may be associated with a high risk of stroke recurrence.

Aged↗
PubMed1998

The need to quantify right-to-left shunt in acute ischemic stroke: a case-control study.

BACKGROUND AND PURPOSE: Although right-to-left shunt (RLSh) has been reported to be significantly more frequent in young stroke patients with cryptogenic stroke, its relevance in a nonselected population of acute ischemic stroke is not well known. The aim of this study was to determine the importance of the RLSh magnitude as a risk factor for stroke in nonselected patients. METHODS: Two hundred eight patients hospitalized consecutively with transient ischemic attack or acute cerebral infarction and 100 healthy control subjects were studied. Transcranial Doppler ultrasonography (TCD) was performed in both middle cerebral arteries (MCAs) after intravenous application of agitated saline solution. The magnitude of RLSh was quantified by counting the number of signals in 1 MCA during a Valsalva maneuver. RLSh was classified as "no shunt," "small" (< 10 signals), and "large" (> 10 signals), with the latter including the "shower" (> 25 signals) and "curtain" (uncountable signals) patterns. Extensive investigations, including contrast transesophageal echocardiography, were carried out on patients diagnosed as suffering from stroke of an uncertain etiology. The importance of RLSh for stroke was assessed by logistic regression analysis. RESULTS: Contrast TCD detected a large RLSh in 40 (19.7%) patients and in 21 (21%) control subjects, all with cardiac RLSh characteristics. A large RLSh was present in 4.7% of atherothrombotic strokes, 10.5% of cardioembolic strokes, 15.4% of lacunar strokes, and 45.3% of cryptogenic strokes (P<0.001). Although the overall frequency of RLSh was not significantly different between patients and control subjects, the detection of curtain or shower patterns by contrast TCD was associated with a higher risk of stroke (odds ratio, 3.5; 95% confidence interval, 1.29 to 9.87), particularly with cryptogenic stroke (odds ratio, 12.4; 95% confidence interval, 4.08 to 38.09) after adjustment for concomitant vascular risk factors. CONCLUSIONS: It is essential to quantify RLSh by contrast TCD during the Valsalva maneuver given that only those with shower and curtain patterns are associated with a higher risk of ischemic stroke in a nonselected population.

Acute Disease↗
PubMed1998

[Record of neurological emergencies at a tertiary care hospital].

INTRODUCTION AND OBJECTIVE: There is a progressive increase in the demand for multidisciplinary attention from the Emergency Medical Services. The objective of this study was to determine the proportion of neurological conditions in the total hospital emergency workload, their demographic composition and medical needs. PATIENTS AND METHODS: We present an observational study of a cohort of histories of neurological emergencies at a tertiary hospital during a period of one year. RESULTS: On analysis of all emergencies, 1,592 were neurological conditions. The duty neurologist was consulted in 87.9% of the cases. The average age was 59, and the majority were women (56.3%). Maximum demand was between 14.00 and 19.59 hours. Monday was the day of the week when most were seen. The commonest causes of consultation were change in strength or language, headache and epileptic crises. The complementary investigation done most frequently was a blood test. Cerebral CT scan were done in 31.9% of the patients. The diagnoses most often made, as a group, were cerebrovascular disease followed by epilepsy and headache. The majority of the patients were referred to Primary Care Centres or for neurological consultation. When the patients were grouped according to the specialties with doctors on duty, the second largest group were seen by the emergency neurologist at our hospital. CONCLUSION: In view of the above results, we consider the presence of a neurologist in the Emergency Department to be fully justified.

Adolescent↗
PubMed1998

[Subarachnoid hemorrhage as a form of onset of systemic lupus erythematosus].

INTRODUCTION: The most frequent cause of spontaneous subarachnoid hemorrhage (SAH) is rupture of intracranial arterial aneurysms (> 70%). The remainder are due to many different aetiologies. Although SAH is a relatively common neuropathological finding in systemic lupus erythematosus (SLE), it is normally due to the extent of the intercerebral hemorrhage and not to its isolated presentation. CLINICAL CASE: We report the case of a 34 year old woman who presented with non-traumatic SAH at the onset of her lupus disorder. The patient was attended for SAH and at the same time a multisystemic disorder and severe thrombocytopenia were found, leading to a diagnosis of SLE. The neuroimaging techniques, selective cerebral arteriography, cerebral and spinal magnetic resonance, and magnetic resonance angiography did not show any vascular malformations. The patient was treated with immunosuppressive therapy, nimodipine, and following angiographic tests, with antiaggregants and anticoagulants. CONCLUSIONS: The greater frequency of SAH in patients with lupus, as compared to the general population, has been attributed to the presence of intracranial vasculitis. However, neuropathological studies have shown that true vasculitis is very infrequent in the central nervous system of SLE patients. In the case we describe, the first in which SAH appeared at the onset of the disease, we consider that the origin of the hemorrhage was her high arterial blood pressure and thrombopenia.

Adult↗
PubMed1996

[Predictive mortality factors and the development of major complications in non-traumatic subarachnoid hemorrhage].

Our aim was to analyze death prognostic factors in the first six months or the development of major neurological complications (delayed brain ischaemia and rebleeding) or general complications (cardiorespiratory, hydroelectrolytic or infectious) in non-traumatic subarachnoid haemorrhage. We carried out an observational study of a historical cohort of 111 patients admitted consecutively to our Centre between 1986 and 1992 and who were diagnosed as having subarachnoid haemorrhage based upon clinical data and confirmed in all cases by brain computerized tomography (CT) scan and/or lumbar puncture. Clinical variables upon admission were collected prospectively and radiological data were obtained retrospectively. We performed a logistic regression analysis which showed as significant predictive variables for death in the first six months a score on the Hunt-Hess scale greater than 2, a score on the Glassow scale of less than 9, female, aged over 50 and rebleeding. As predictive factors for delayed brain ischaemia we identified the female sex and the existence of earlier general complications. In the development of rebleeding a significant predictive factor was high blood pressure antecedents although this may have been controlled upon admission. For the appearance of general complications, significant predictive factors were more than 2 on the Hunt-Hess scale and hypertension antecedents. The use of these predictive parameters may help evaluate a prognosis in subarachnoid haemorrhage patients and also help make decisions in the management of this pathology.

Aged↗
PubMed1992

Measurement of the distribution of [3H]bicuculline microinjected into the rat hypothalamus.

The purpose of this study was to measure the distribution of a radiolabeled drug [3H]bicuculline methylchloride ([3H]BMC) following microinjection into the supraoptic nuclei (SON) and the dorsal hypothalamus of conscious rats. The anteroposterior (AP) distribution was measured using liquid-scintillation counting while computer-assisted densitometry was used to measure the mediolateral (ML) and dorsoventral (DV) distribution of silver grains on autoradiograms. Following a 50-nl microinjection into the SON, 90% of the detected tracer was found within 0.6 +/- 0.1 mm (n = 5) of the injection site. Using the same volume, the pattern of distribution of 90% of the detected tracer in the SON was not significantly altered when rats received a microinfusion over 10 min (n = 5) or a bolus microinjection with a 10 min waiting period (n = 6) prior to death. Following a 100-nl microinfusion over 20 min into the dorsal hypothalamus, 90% of the detected radiolabel was found within 0.6 +/- 0.1 mm (n = 7) of the injection site, in a spherical pattern of distribution. Although caution must be used in extrapolating these results to other drugs, these data suggest that intraparenchymal microinjections of 50- and 100-nl volumes are suitable for drug localization in studies using microinjection techniques for conscious rats.

Animals↗