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At least 703 records · Page 39Linked to original sources
PubMed1993

Acute experimental neuronal injury in the newborn lamb: US characterization and demonstration of hemodynamic effects.

BACKGROUND AND PURPOSE: Microinjection into the brain with N-methyl-D-aspartate (NMDA), a synthetic analogue of glutamate, has been used as a chemical model of perinatal hypoxic-ischemic injury. Little is known about the sonographic characteristics and hemodynamic consequences of these cytotoxic lesions. An understanding of these features may be useful in the early sonographic identification of stroke in newborns. METHODS: Twenty newborn lambs were anesthetized, paralyzed, and mechanically ventilated. Between 0.5 and 5 mu mole NMDA in 0.2 ml phosphate buffered saline, n = 18), or buffered saline only (n = 2) was injected into the right putamen under sonographic guidance. Serial grey-scale and color Doppler images of the brain, Doppler spectra of the middle cerebral and thalamostriate arteries, cerebral blood flow (CBF) determinations using radiolabeled microspheres (n = 9), and cerebral oxygen extraction (n = 4) were obtained before, and at 15.60, and 120 min after NMDA injection. Pathologic examination was obtained in 11 animals. RESULTS: Homogeneous, well defined, moderately echogenic lesions surrounded by marked focal hyperemia on color Doppler were identified in every animal injected with 5 mu mole NMDA within minutes of injection. Lesions were characterized by focal areas of chromatolysis and cytoplasmic shrinkage, with scattered petechial hemorrhage. No lesions or hyperemia were observed in the animals injected with normal saline. Mean supratentorial CBF increased from 64 +/- 9 ml/min/100 g (control) to 152 +/- 30, 115 +/- 19, and 102 +/- 8 ml/min/100 g at 15, 60, and 120 min after injection respectively. The most marked increases occurred in right midbrain (467% of control), diencephalon (388%), and temporal lobe (282%), but were also observed in homotopic regions of the left hemisphere, and in pons, medulla, and cerebellum. Mean blood flow velocity in the middle cerebral artery, and thalamoperforator artery correlated well with changes in hemispheric and midbrain. CBF respectively. (r = 0.57-0.74, p = 0.0001, and r = 0.65-067, p = 0.0001 respectively). CONCLUSIONS: Focal brain lesions may by identified by sonography within minutes after experimentally induced neuronal injury. Alterations in echotexture are primarily due to intracellular cytoplasmic changes and microscopic hemorrhage. Local intracerebral injection of NMDA in newborn lambs increases both local and global CBF.

Acute Disease↗
PubMed1992

Colour-coded echographic flow imaging and spectral analysis of cerebrospinal fluid (CSF) in meningitis and hemorrhage. Part I. Clinical evidence.

Using echographic flow imaging (colour Doppler), flow within ventricular CSF-pathways was discovered in an infant with purulent meningitis. 22 mature and 40 premature infants were then investigated for presence of CSF-flow which was detected in a further 5 infants, all premature. Diagnostic criteria for echographic CSF-flow imaging are: 1. flow signals "within" CSF-pathways; 2. to-and-fro movement of CSF (spectral analysis); 3. specific response of CSF-flow to stimuli (respiration, crying, abdominal palpation); 4. dynamic CSF-imaging related to specific anatomical areas of intracranial CSF-pathways. Echographic detection of CSF-flow depends on optimized adjustment of controls, equipment used, meticulous examination technique and awareness of pitfalls on the part of the examiner. A further prerequisite is the presence of scattering particles within CSF, such as red or white blood cells (minimum concentration in the order of one thousand cells/microL) or air. Although echographic CSF-flow imaging is not applicable for excluding the presence of disease, it appears to be a new diagnostic tool with considerable potential allowing selected early and non-invasive diagnosis of CSF-pathology and giving new insights into CSF-hemodynamics.

Abdomen↗
PubMed1992

Colour-coded echographic flow imaging and spectral analysis of cerebrospinal fluid (CSF) in infants. Part II. CSF-dynamics.

41 comprehensive colour Doppler studies (including spectral analysis) of the ventricular system were performed in 6 infants with CSF-flow (age range: 2 to 27 days). Two premature infants showed no evidence of disease related to the central nervous system (CNS). Overt intraventricular hemorrhage or CNS-infection were present in the other infants. All children were examined several times until CSF-flow was no longer visible. The entire ventricular system, including the fourth ventricular outlet, was investigated for the presence of CSF-flow signals. Dynamic CSF-flow studies consisted of scanning during typical infant activity (crying, sucking, leg movement) and with external manoeuvres (abdominal or fontanellar palpation). CSF-flow was found to be: 1. synchronous with respiration 2. induced by rising intraabdominal (retrograde CSF-pulse) and transfontanellar pressure (orthograde CSF-pulse) 3. predominantly within the cerebral aqueduct, but also found at the foramina of Monro, within the third and fourth ventricles and at the foramen of Magendie. CSF-flow was not detected at the foramina of Luschka or within the lateral ventricles, except adjacent to the foramina of Monro. Dynamic CSF-flow as observed in infants may have important clinical and scientific implications. Examples of this are activity-related ventricular "reflux" of bacteria, erythrocytes, drugs, radionuclides or contrast; the importance of CSF-flow pulses for the development or progression of hydrocephalus; flow dynamics at the fourth ventricular outlet foramina and the study of CSF-pulse wave velocity and regional compliance. These issues are discussed and the new diagnostic approach is compared with other methods of CSF-investigation.

Abdomen↗
PubMed1992

Colour-coded echographic flow imaging and spectral analysis of cerebrospinal fluid (CSF). Part III. In-vitro study of low flow velocity detection related to decreasing particle concentration (hematocrit) and tube lumen.

An in-vitro steady flow system was designed to determine the lowest flow velocities that can be detected by echographic colour flow imaging and spectral analysis. The flow detection level was determined hydrostatically by reducing the fluid level to below the point at which a flow signal was visible, then increasing the height until the colour flow reappeared. This was confirmed in all instances by spectral analysis. The height (angle-corrected velocity) of the spectral envelope was also determined. Mean volume flow was then obtained by using a graduated cylinder and a stop watch. The lowest hematocrit detectable was identified using a stepwise dilution of packed human red blood cells with 0.9% sodium chloride. Three different PVC-tubes with inner diameters of 2.1 mm, 1.1 mm and 0.51 mm were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1992

Connatal periventricular pseudocysts in the neonate.

Connatal periventricular pseudocysts are important sequelae of different noxious insults in the developing brain. Accurate diagnosis of those pathologic entities during early life has therefore become of direct concern to the clinician. Our experience with 12 infants of connatal periventricular pseudocysts provides the basis of this study. They belonged to different pathological entities: focal paraventricular pseudocysts (5 cases), subependymal pseudocyst (3 cases), connatal viral infection (3 cases), and chromosomal abnormality (1 case). When present at birth, they suggest an intrauterine pathology. It has only been with the advent of real-time cranial ultrasound that periventricular pseudocystic lesions can be detected in neonates following an abnormal pregnancy. Some obstetric complications during the second trimester can cause paraventricular or subependymal pseudocyst in the foetus. Neurotrophic viral infection and chromosomal abnormalities have also been implicated in the production of cystic lesions in this region. These lesions are not a terminal event in infants but may be a condition of major clinical importance for further neurological development.

Brain Diseases↗
PubMed1991

Lissencephaly in two brothers detected by US. A "pseudo-liver" pattern.

We report on two cases of lissencephaly in two brothers studied by high frequency ultrasound and subsequently confirmed by CT and, in one case, by post-mortem study. In addition to well known sonographic and CT signs described in the literature, a typical structural change of the brain (named "pseudo-liver") was detected using high-frequency sonography.

Brain↗
PubMed1993

Cranial ultrasound findings in aspartoacylase deficiency (Canavan disease).

Canavan disease (CD) is a rare leukodystrophy which is lethal in infancy or early childhood. The underlying biochemical abnormality in CD is a hereditary deficiency of N-aspartoacylase transmitted in an autosomal recessive fashion. We report on the ultrasound (US), CT, and MRI findings of three unrelated boys with biochemically confirmed CD. At 6 and 9 months of age, two CD patients with rapid neurological deterioration showed markedly enhanced acoustic attenuation of the white matter with the exception of the corpus callosum, giving the appearance of a reversed pattern of echogenicity of cortical gray and subcortical white matter. While gyri and sulci had an almost normal US appearance, the periventricular gray matter featured prominently with increased echogenicity. In contrast another CD patient with a more protracted course had ventricular enlargement when examined by US at 5 and 9 months but no alteration in white matter echogenicity. MRI showed impaired myelinization in all three patients with Canavan disease.

Canavan Disease↗
PubMed1993

Hemimegalencephaly: early sonographic pattern.

The sonographic changes in a 30-day-old infant with hemimegalencephaly are reported and compared with the CT and MRI findings. Sonography demonstrated the characteristic anomaly of the white matter not shown until later by CT and MRI.

Brain↗
PubMed1992

Colour Doppler imaging of intracranial vasculopathy in severe infantile sialidosis.

Neonatal ascites is usually attributed to prenatal infections, lysosomal storage disease and anomalies of the genitourinary tract, gastrointestinal tract or cardiovascular system. We report one case of neonatal ascites associated with infantile sialidosis. Cerebral sonography showed stripe-like intracerebral echogenicities in the region of the basal ganglia. Colour Doppler imaging demonstrated blood flow within the echogenicities confirming the suspected diagnosis of intracranial vasculopathy.

Adult↗
PubMed1992

Hyperechoic lesions in the basal ganglia: an incidental sonographic finding in neonates and infants.

Cerebral ultrasound (US) imaging was performed as a screening procedure in approximately 3,600 neonates and infants over a period of 18 months. Hyperechoic lesions in the basal ganglia and thalamic region were detected incidentally in 15 of these patients. Clinical diagnoses included cytomegalovirus infection, asphyxia, rotavirus infection, prematurity, amniotic infection, dysmorphic stigmata, hyperbilirubinemia, congenital heart disease, and diabetic fetopathia. Lesions showed a single punctate (n = 5), multiple punctate (n = 8), or stripe-like pattern (n = 2), with no disease-specific distribution. Computed tomography performed in two of the 15 patients was normal. Lesions resolved within four to seven months in four of eleven cases who had follow-up studies, whereas echogenicities persisted in the remaining seven patients over a period of observation ranging between one to 15 months. Our results indicate that hyperechoic lesions in the basal ganglia and thalamic region may be associated with congenital infections and asphyxia, but could indicate some other unknown pathology. No correlation was found between the morphology of foci and both clinical diagnosis and results of follow-up studies.

Basal Ganglia Diseases↗
PubMed1992

Cerebral contusional tears as a marker of child abuse--detection by cranial sonography.

A series of 6 infants subjected to child abuse is presented in whom contusional tears of subcortical white matter were detected during life by intracranial sonography. The sonographic appearances of this highly pathognomonic marker of shaking injury are described for the first time and their significance discussed. On the basis of our experience we suggest that high resolution cranial sonography is an extremely valuable part of the diagnostic work up in cases of suspected non-accidental injury.

Brain Concussion↗
PubMed1992

Cerebrovascular resistive index assessed by duplex Doppler sonography and its relationship to intracranial pressure in infantile hydrocephalus.

Duplex Doppler sonography and direct intracranial pressure (ICP) measurement were performed on 18 patients with infantile hydrocephalus. ICP was measured through a frontal reservoir or ventricular tap using a nondisplacement pressure transducer. The Pourcelot Resistive Index, RI = (peak systolic-end diastolic)/peak systolic velocity was obtained from pulsed-wave Doppler measurements of blood flow velocity in the anterior (ACA) and/or the middle cerebral (MCA) arteries. There was a statistically significant positive correlation between ICP and RIs in the MCA and ACA. Paired RI measurements in 7 patients with raised ICP decreased significantly from a mean of 0.90 pre-tap to 0.75 post-tap. Our results suggest that the RI provides a reliable measure of cerebrovascular resistance in hydrocephalus. Duplex Doppler ultrasonography thus is a useful noninvasive means of monitoring cerebrohaemodynamic change with simultaneous imaging of ventricular size in infantile hydrocephalus.

Blood Flow Velocity↗
PubMed1993

Continuous transcranial Doppler ultrasonography and electroencephalography during carotid endarterectomy: a multimodal monitoring system to detect intraoperative ischemia.

Transcranial Doppler ultrasonography (TCD) and EEG monitoring during carotid endarterectomy provide continuous information on the electrical activity of the cerebral cortex, blood flow velocities in the ipsilateral middle cerebral artery, and the occurrence of microemboli. One hundred thirty carotid endarterectomies performed with TCD and EEG monitoring were studied prospectively. During cross-clamping of the carotid artery a high correlation was found between EEG asymmetry and reduction of blood flow velocity in the middle cerebral artery (p < 10(-6), Student's t test). Microemboli were detected in 80 patients during the operation. Although not statistically significant, this occurrence of microemboli was associated with signs and symptoms of intraoperative ischemia (p = 0.08, Fisher's exact test). In comparison with earlier studies, a tendency toward intraoperative stroke reduction was noted. Only one nondisabling intraoperative stroke occurred (0.8%). In addition to the EEG, TCD monitoring of hemodynamic changes and microemboli in the middle cerebral artery provides important information to the surgeon instantaneously. TCD monitoring of blood flow velocities and embolism during carotid endarterectomy may help to reduce the number and gravity of intraoperative stroke.

Adult↗
PubMed1993

The role of vertebral and internal carotid artery disease in the pathogenesis of vertebrobasilar transient ischemic attacks.

Color-coded duplex sonography has improved the evaluation of the hemodynamics of the vertebral arteries (VA). A reliable differentiation between a normal vessel, hypoplasia, stenosis and occlusion of VA can now be made. We studied two groups of patients in a prospective study with isolated carotid artery disease (n = 48), and with a combination of carotid and vertebral artery disease (n = 14), to determine the role of VA in the pathogenesis of transient ischemic attacks (TIAs) in the vertebrobasilar system. Apart from the existing arteriosclerotic changes of the internal carotid arteries, the condition of the VA was of importance for the occurrence of TIAs in the vertebrobasilar territory. We found that 8% of the patients with isolated hemodynamically relevant stenosis or occlusion of one or both internal carotid arteries had a TIA in the vertebrobasilar territory. Patients with combined carotid and vertebral artery disease had an increase of TIAs in the same region in 71%. The high rate of TIAs in this group might be attributed to the combined effect of carotid and vertebral artery disease, as a third group (n = 30) with isolated vertebral artery disease showed TIAs in only 13%.

Blood Flow Velocity↗
PubMed1991

Three-dimensional transcranial Doppler in acute ischemic stroke in the territory of the middle cerebral artery: clinical and CT correlation.

We studied 34 patients with acute ischemic stroke in the territory of the middle cerebral artery (MCA) by three-dimensional transcranial Doppler (TCD-3D). The parameters analyzed were: mean blood flow velocity, systolic and diastolic velocities; indices of pulsatility, hemisphere asymmetry and pulsatility transmission. Of the 34 patients 11 presented marked slowing of flow velocity in the MCA on the infarct side with an asymmetry index (AI) of over 40%, 8 patients with slightly reduced flow velocity in the MCA and an AI of 25-40%, 2 patients in whom there was indirect evidence of collateral circulations in the anterior cerebral artery distribution together with slowing of MCA flow; 5 patients had stenosis of the MCA, 9 patients showed no alterations of the Doppler parameters. The correlation between neurological symptom pattern and AI was significant (r = 0.76). Noninvasive, easy to perform, performable at once and reliable, TCD-3D is a great improvement on traditional transcranial Doppler and is especially useful in assessing the hemodynamics of the cerebral circulation in ischemic stroke.

Acute Disease↗
PubMed1994

Stroke in a young woman due to spontaneous bilateral internal carotid dissection. A case report.

The present paper reports the case of a young woman who experienced an ischemic stroke due to the spontaneous dissection and occlusion of both internal carotid arteries, with recanalisation one year after the event. It is underlined that this form is not clinically different from the unilateral form, and that it is often associated with a favourable prognosis. In addition to the characteristic angiographic findings, the paper also highlights the importance of the combined use of MR, MR angiography and echo-Doppler imaging during diagnosis and follow up.

Adult↗