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Biomedical subjects

M H Gado

Publications and source records attributed to M H Gado.

At least 55 records · Page 3Linked to original sources
PubMed1979

Central nervous system lesions biopsied or treated by CT-guided needle placement.

Computed tomography has been utilized to guide a needle into central nervous system lesions as small as one centimeter in diameter. Direct puncture has drained many abscesses effectively, provided material for immediate Gram stain and subsequent culture, and permitted irrigation with appropriate antibioties, Multilocular cerebral lesions and loculated extracerebral fluid collections have been aspirated and treated with this technique. Aspiration of known cystic tumors has reduced their mass and obviated some palliative decompressions. Unresectable gliomas and metastases have been biopsied prior to chemotherapy or radiotherapy. Hemorrhage and other rare complications of biopsy may be detected and immediately treated.

Adolescent↗
PubMed1979

Regional cerebral blood flow and oxygen utilization in superficial temporal-middle cerebral artery anastomosis patients: an exploratory definition of clinical problems.

Regional cerebral blood flow (rCBF) and regional cerebral oxygen utilization (rCMRO2) were measured before and after surgery in nine patients undergoing a superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis to bypass cerebrovascular lesions not amenable to extracranial operative procedures. The objective of these studies was to determine whether measurements of this type could provide objective criteria for surgery as well as assess the effect of surgery. The preliminary data, although limited, suggest that measurements of regional cerebral hemodynamics and metabolism in these patients before and after surgery provide valuable data upon which to develop criteria and assess results. For example, 1) a significant depression of rCBF and rCMRO2 in patients in whom a major cerebral infarction has not occurred, or 2) relative preservation of rCMRO2 despite depressed rCBF seem to be favorable indications for establishing a functioning STA-MCA anastomosis. In such patients, STA-MCA anastomosis can be followed by a return of rCBJ and rCMRO2 to virtually normal levels. Relatively normal rCBF and rCMRO2 in the presence of an occluded internal carotid artery in asymptomatic patients indicates satisfactory collateral circulation and is probably a contraindication to surgery.

Adult↗
PubMed1978

Cerebral hemodynamics and metabolism in pseudotumor cerebri.

A comprehensive analysis of cerebral hemodynamics and metabolism was carried out in 14 patients with pseudotumor cerebri. Tracer techniques were employed to measure cerebral blood flow (CBF) and vascular reactivity to acute changes in arterial carbon dioxide tension and blood pressure, cerebral blood volume (CBV), and the cerebral metabolic rate for oxygen and glucose. There was a small reduction (p less than 0.01) in CBF (44 +/- 7 ml/100 gm/min; normal, 54 +/- 9) with normal vascular reactivity; an increase (p less than 0.005) in CBV (4.8 +/- 0.8 ml/100 gm; normal, 3.6 +/- 0.5), and normal cerebral metabolism. We conclude that an abnormality of the cerebral microvasculature is responsible for an elevation in CBV, but the intracranial hypertension can be explained only by tissue swelling due to an increase in water content. The relationship between the vascular abnormality and the tissue swelling remains to be defined.

Adolescent↗
PubMed1978

Adult idiopathic communicating hydrocephalus with and without shunting.

The outcome in 37 adult patients with idiopathic communicating hydrocephalus treated by ventriculoatrial shunting is presented. Only 33% showed definite improvement, and no diagnostic procedures accurately predicted the outcome of surgery. These were compared with a "control" group of 12 patients who were not shunted; 50% of these were stable for up to 36 months. These findings, and the high frequency of serious complications (35%), suggest caution in recommending a shunt procedure.

Aged↗
PubMed1978

Computerized tomography of the orbit.

The potential for using CT to diagnose orbital lesions is clearly demonstrated in this chapter. The patients discussed were all suffering from proptosis and had other complaints such as visual disturbances, pain, or ophthalmoplegia. CT is superior to ultrasonography in its ability to reproduce anatomical structures, including the retroocular space, bony walls of the orbit, and extraorbital regions, such as ethmoid sinuses and the cranial cavity. Such reproduction helps distinguish lesions arising within the orbit from those invading the orbit from outside. CT not only defines the extent of a lesion but also provides information about the physical properties of the tissue. The remarkable difference on CT between proptosis caused by thyrotoxic disease and that caused by intraorbital tumor or pseudotumor is a striking example of the way in which CT may contribute to more accurate diagnosis.

Adolescent↗
PubMed1977

Computerized cranial tomography and radionuclide imaging in the detection of intracranial mass lesions.

Computerized cranial tomography (CCT) and radionuclide imaging (RI) of the brain are both accurate techniques for detecting intracranial mass lesions. CCT is superior in detecting low-grade gliomas, cystic lesions, parasellar tumors, and brain stem lesions. Overall, CCT detection rates are slightly higher than those with RI, but the use of iodinated contrast media with CCT increases the risk of this examination. There is a significant difference in the generally binary (positive/negative) type of information offered by RI and the more specific information offered by CCT about the pathologic nature of a lesion and its precise location. In the evaluation of patients with suspected intracranial mass lesions, CCT is generally the preferable initial diagnostic test. However, RI may still serve as a satisfactory screening examination in certain well-defined clinical situations.

Brain Abscess↗
PubMed1977

Cerebral blood flow, oxygen utilization, and blood volume in dementia.

Patients with dementia had significant decreases in cerebral blood flow and cerebral oxygen utilization and a mild, but not significant, increase in cerebral blood volume. These studies were not useful in distinguishing patients with cerebral atrophy from patients with normal pressure hydrocephalus, as similar changes in cerebral circulation and metabolism were seen in both groups. Changes in cerebral blood flow after acute decrease in the intracranial pressure also were not helpful differentiating patients with normal pressure hydrocephalus from patients with cerebral atrophy.

Blood Volume↗
PubMed1977

Coxsackie A9 focal encephalitis associated with acute infantile hemiplegia and porencephaly.

The factors underlying acute infantile hemiplegia are seldom identified. Coxsackie A9 focal encephalitis was documented for the first time in a 3-month-old infant with fever, hemiconvulsions, and hemiplegia followed by a static motor deficit and epilepsy. It has been suggested that the acute infantile hemiplegia associated with encephalitis results from an arteritis or venous sinus thrombosis with subsequent cerebral infarction. However, this was not observed in our patient. Rather, a series of brain scans, computerized tomograms, and a cerebral angiogram clearly documented the evolution of a focal necrotizing encephaloclastic process resulting in a porencephalic cyst. Serial cerebrospinal fluid viral cultures were necessary to isolate the etiologic agent (tcoxsackie A9). The infant did not have a neutralizing antibody response to the infecting viral agent despite an apparently intact immune system, which possibly may be explained by the developed of immune tolerance or an insufficient amount of infecting viral antigen. This emphasizes that serologic studies alone may not be adequate to document an acute central nervous system viral infection. This patient also typifies the poor prognosis in infants presenting with acute hemiplegia, fever, and convulsions in the absence of cerebrovascular occlusion.

Acute Disease↗
PubMed1977

Effects of subarachnoid hemorrhage on cerebral blood volume, blood flow, and oxygen utilization in humans.

Forty-five studies of regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and regional cerebral oxygen utilization (rCMRO2) were performed in 30 patients undergoing diagnostic cerebral angiography for evaluation of a subarachnoid hemorrhage due to a ruptured intracranial aneurysm. Tracer methods employing radioactive oxygen-15 were used to measure rCBV, rCBF, and rCMRO2. The patient studies were divided into groups based on their neurological status and the presence or absence of cerebral vasospasm. Subarachnoid hemorrhage, with and without vasospasm, produced significant decreases in CBF and CMRO2. In general, patients with more severe neurological deficits, and patients with more severe degrees of vasospasm, had a more marked depression of CBF and CMRO2. The most striking finding was a significant (p less than 0.001) increase in CBV (to 58% above normal) in patients with severe neurological deficits associated with severe cerebral vasospasm. This large increase suggests that cerebral vasospasm consists of constriction of the large, radiographically visible extraparenchymal vessels accompained by a massive dilation of intraparenchymal vessels.

Blood Pressure↗
PubMed1976

Correlation between regional cerebral blood flow and oxidative metabolism. In vivo studies in man.

To test the hypothesis that regional cerebral blood flow (rCBF) is normally regulated by regional metabolic activity, rCBF and the regional cerebral metabolic rate for oxygen (rCMRO2) were compared in selected human subjects. In normal subjects and patients with chronic, stable diseases of brain, rCBF correlated well with rCMRO2. In one individual with mild dementia, rCBF and rCMRO2 were measured before and during exercise of the hand and forearm contralateral to the hemisphere studied. Appropriate parallel changes occurred in both rCBF and rCMRO2 during hand exercise. In patients with acute diseases affecting the hemisphere studied, however, the correlation between rCBF and rCMRO2 was unpredictable.

Brain↗
PubMed1976

Changes in cerebral blood volume and vascular mean transit time during induced cerebral seizures.

The relationship of the mean transit time of the vascular indicator C15O-labeled hemoglobin (tco) and the cerebral blood volume (CBV) as measured by stimulated x-ray fluorescence, to the mean arterial blood pressure (MABP) was examined in rhesus monkeys before and during experiment cerebral seizures. The results demonstrate a marked increase in CBV and a decrease in tco. A substantial portion of these changes is the passive accompaniment of the associated increase in MABP.

Animals↗
PubMed1976

Correlation between computerized transaxial tomography and radionuclide cisternography in dementia.

A study of the findings on cisternograms and computerized transaxial tomography (CTT) of 144 patients showed good correlation between the two tests. Patients with a cisternographic pattern of communicating hydrocephalus tended to show more severe degrees of lateral ventricular dilation, with involvement of the third and fourth ventricles and relative sparing of the cerebral sulci. Patients with a cisternographic pattern of cerebral atrophy showed lesser degrees of lateral ventricular dilatation and more severe degrees of dilatation of the cerebral sulci. The statistical significance of the individual CTT findings in these patients is presented, and a cheme for interpretation is proposed. The study shows that CTT can replace pneumoencephalography in evaluating patients with dementia, while cisternography contributes complementary information.

Brain Diseases↗
PubMed1975

Correlation of effective atomic number and electron density with attenuation coefficients measured with polychromatic x rays.

Attenuation coefficients of nine different plastics and water were measured with EMI computed transaxial tomography (CT) and radioisotopic sources with photons of 14 to 136 keV. The EMI values were correlated with physical density, electron density, and atomic number cubed (Z3). The best correlation was obtained with electron density, the exception being the value for water. This descrepancy was explained on the basis of X-dependent photoelectric absorption with verification from monoenergetic measurements.

Computers↗
PubMed1975

An extravascular component of contrast enhancement in cranial computed tomography. Part I. The tissue-blood ratio of contrast enhancement.

One can calculate the tissue-blood ratio of enhancement by analyzing the quantitative aspects of the CT scans of the cranium and blood samples both before and after the injection of contrast medium. This ratio is equivalent to that between the iodine content of a given volume of tissue and an equal volume of blood. Analysis of 47 normal patients, including 27 with pathological brain lesions, indicated that there is significant extravasation of contrast medium in patients with such lesions.

Brain↗
PubMed1975

An extravascular component of contrast enhancement in cranial computed tomography. Part II. Contrast enhancement and the blood-tissue barrier.

The authors provide evidence of significant extravasation of contrast media responsible for the contrast enhancement of pathological tissue on computed tomography. The tissue-blood ratio of enhancement was calculated by the EMI scanner in 2 patients after injection of contrast material and prior to surgery; tumor-blood ratios for red blood cell and plasma tracers were calculated after surgery. The ratios of enhancement demonstrated the analogy between contrast enhancement and the leaking of radionuclide across the blood-brain barrier. This phenomenon may cause error if this technique is used for the measurement of cerebral blood volume. The area for complementary roles of CT and radionuclide brain imaging seems to be narrower than expected.

Animals↗
PubMed1975

Radiological visualization of the vestibular aqueduct. Technique and morphological features.

Thin-section tomography in the lateral and off-lateral projections permits radiographic visualization of the vestibular aqueduct, which is seen as an inverted J. The proximal curved portion has a constant configuration, while the distal straight portion varies according to the width of the external aperture and may be tubular, funnel-shaped, or filiform. Nonvisualization of the curved portion does not necessarily mean that it is not present.

Contrast Media↗
PubMed1975

Linear nevus sebaceous syndrome associated with porencephaly and nonfunctioning major cerebral venous sinuses.

An infant with the linear nevus sebaceous syndrome also had new findings of porencephaly and nonfunctioning major cerebral venous sinuses. This infant is the first described with the syndrome to undergo angiographic study. Similar nonfunctioning major cerebral venous sinuses are seen in the Sturge-Weber syndrome. A leptomeningeal angioma recently was reported in a newborn with the linear nevus sebaceous syndrome. The central nervous system disturbances in this syndrome might be secondary to developmental vascular anomalies. Therefore, the linear nevus sebaceous syndrome exhibits important similarities to the Sturge-Weber variety of neurocutaneous syndrome.

Brain↗