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Biomedical subjects

L A Alvarez

Publications and source records attributed to L A Alvarez.

At least 37 records · Page 2Linked to original sources
PubMed1988

Brain death determination by angiography in the setting of a skull defect.

The absence of cerebral blood flow is presently considered the most reliable ancillary test in diagnosing brain death. A patient with an open skull fracture who met all criteria for brain death, including confirmatory postmortem studies, had a cerebral angiogram that showed unilateral preservation of cerebral circulation with diffuse extravasation of contrast material. We conclude that a skull defect may result in pressure reduction within the cranial cavity and persistent ipsilateral cerebral circulation, even after brain death. In this setting, diffuse extravasation of contrast material on angiography may reflect diffuse autolysis and suggest the diagnosis of brain death.

Adult↗
PubMed1988

Fatigue in multiple sclerosis.

Fatigue is a frequent symptom in multiple sclerosis (MS) that can interfere with a patient's daily functioning. The cause of MS fatigue, its clinical characteristics, and its relationship to other symptoms remain poorly understood. Structured interviews were conducted with 32 patients with MS and 33 normal healthy adults. Fatigue proved to be both more frequent and more severe among the patients with MS. Multiple sclerosis fatigue was unrelated to either depression or global impairment. Multiple sclerosis fatigue appears to be a distinct clinical entity, often disabling, that can be distinguished from normal fatigue, affective disturbance, and neurologic impairment.

Adult↗
PubMed1988

EEG and brain death determination in children.

In a retrospective study involving several medical centers we identified 52 patients under age 5 years who met the adult clinical criteria for brain death and had at least one EEG with electrocerebral silence. Of the 52 patients, 31 died spontaneously and 21 were disconnected from the respirator. Repeat EEGs were obtained in 28 patients, and in all electrocerebral silence persisted. The study suggests that clinical criteria similar to those used for adults in the determination of brain death can also be applied to children above age 3 months and that a single EEG with electrocerebral silence is sufficient to confirm brain death in this age group.

Brain↗
PubMed1988

Stage IV breast cancer: clinical course and survival of patients with osseous versus extraosseous metastases at initial diagnosis. The GOCS (Grupo Oncológico Cooperativo del Sur) experience.

The medical records of 414 patients with metastatic breast carcinoma treated between 1978 and 1986 were reviewed and 44 women were identified as having stage IV disease when the primary breast lesion was detected. Of these 44 women, 25 had metastatic disease limited to the skeleton while 19 had extraosseous lesions only. The clinical features, response to therapy, and survival were analyzed and compared for both groups. The median survival of those patients with bone-only metastases was 52 months as compared with 13 months for those with extraskeletal lesions (p = 0.0025). The response rate to first-line systemic therapy was similar for both groups (47% for bone metastases and 44% for extraosseous metastases). The median duration of response was 14 months (range, 3-55 months) for patients with bone disease and 8 months (range, 4-43 months) for those with extraskeletal lesions. We conclude that patients with metastatic breast cancer confined to the skeleton at initial diagnosis tend to follow an indolent, chronic course with prolonged survival. Therefore the increase in response rate with aggressive chemotherapy should be balanced against its higher morbidity. Further studies are needed to confirm whether the better prognosis of these patients is determined by the anatomical confinement of the disease to the skeleton or merely reflects the influence of other prognostic factors.

Bone Neoplasms↗
PubMed1987

Ependymal foldings and other related ependymal structures in the cerebral aqueduct and fourth ventricle of man.

The ependymal lining of the cerebral aqueduct and fourth ventricle of 100 normal humans was studied with the light microscope. Ependymal foldings with normal morphology and a constant distribution pattern were detected in all. The most common sites were the median sulcus and sulcus limitans in the fourth ventricle, and the ventral and lateral walls in the cerebral aqueduct. Rows, islands and rosettes of ependymal cells embedded in normal subependyma were present in 25/82 adults (30%) and in 3/18 children (16%) in a similar distribution pattern as that of the ependymal foldings. We illustrate these normal structures which probably result from fusion between the walls of the ependymal foldings and distinguish them from granular ependymitis and postmortem artifact.

Adult↗
PubMed1987

Computed tomography of the brain in the Smith-Lemli-Opitz syndrome.

Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.

Brain↗
PubMed1987

External hydrocephalus: radiologic spectrum and differentiation from cerebral atrophy.

External hydrocephalus (EH) is a condition in which infants with rapidly enlarging heads are found to have a CT scan that shows widening of the subarachnoid space with mild or no ventricular dilation. In this study, 74 infants with EH associated with a variety of conditions were examined clinically and with CT scans to identify the radiologic features of the condition as well as to understand its clinical and radiologic evolution. Some of these CT scans were compared with those of patients with cerebral atrophy. The characteristic CT findings in EH were bifrontal widening of the subarachnoid space and widened interhemispheric fissure frontally with only mild enlargement of the rest of the subarachnoid space. Occasional mild to moderate ventriculomegaly was also present. In most cases the radiologic findings could be distinguished from those seen in cerebral atrophy, even without the clinical history of an enlarging head. The cases of cerebral atrophy showed prominent sulci throughout without disproportionate bifrontal widening of the subarachnoid space. Two major groups of infants are identified. The largest group (47) consisted of infants with primary megaloencephaly. Megaloencephaly was idiopathic in 40 infants, many of whom (19) met the criteria for benign familial macrocephaly. Others (7) had a clearly defined genetic syndrome. The radiologic abnormalities in these infants usually disappear by 2 years of age. The other major group (14) consisted of infants who sustained CNS or systemic insults such as subdural hematomas (8) or meningitis (3), which cause impaired CSF absorption. Thirteen premature infants with EH were also identified. It is concluded that EH is an age-related self-limited condition occurring in infants with open cranial sutures and that usually resolves without intervention by 2-3 years of age.

Atrophy↗
PubMed1986

Diagnosis of brain death in children.

During the last two decades, criteria have been developed for the diagnosis of brain death that are applicable to adults and children over 5 years of age. To identify brain death, EEG and evoked potentials (EPs) have been extensively used as diagnostic tools in conjunction with the clinical examination and other laboratory procedures such as four-vessel cerebral angiograms or radionuclide scans. In this report, we review the criteria for the determination of brain death. In addition, the question of applying these criteria to children under 5 years of age is critically assessed, with special emphasis on the role of EEG and EPs in confirming the cessation of all brain activities. We propose that the criteria that pertain to adults may be appropriate for children under 5 years of age as well; however, this premise needs to be validated by a large nationwide multi-institutional study.

Adult↗
PubMed1986

Miller-Dieker syndrome: a disorder affecting specific pathways of neuronal migration.

A patient with the typical craniofacial features and clinical course of Miller-Dieker syndrome (MDS) was found on autopsy to have focal pachygyria rather than lissencephaly. The brainstem and cerebellum were hypoplastic, but thalami and basal ganglia were normal. We believe that MDS is a syndrome in which multiple specific pathways of neuronal migration are affected selectively, such as migration to the neocortex, migration via corpus pontobulbare, and cerebellar migration. However, another migration pathway (via corpus gangliothalamicum) is spared.

Abnormalities, Multiple↗
PubMed1986

Idiopathic external hydrocephalus: natural history and relationship to benign familial macrocephaly.

External hydrocephalus was identified in 63 infants. The 36 infants in whom external hydrocephalus was idiopathic constitute the study population. The group was homogeneous. Although not all were macrocephalic at birth, the head circumference exceeded the 95th percentile in all cases by 1 year of age, and subsequent head growth was parallel to the 95th percentile. The head computed tomographic scan showed a characteristic picture of a prominent interhemispheric fissure, a collection of subarachnoid fluid over the frontal convexities, and prominent basal cisternae. Mild ventriculomegaly was present in ten cases. These abnormalities resolved after 18 to 24 months of age. No infant required therapy for the condition. Development was normal in 32 infants, suspect in three, and clearly abnormal in only one of the 36 infants. However, of the 32 infants with normal development, 14 were found to be delayed in gross motor development and five in language development at a prior time. There was a family history of macrocephaly in 88% of cases. Several families had a mixture of members with external hydrocephalus and benign familial macrocephaly throughout several generations. These findings suggest that idiopathic external hydrocephalus is a relatively benign, self-limited condition that resolves without treatment and is closely related to benign familial macrocephaly.

Black People↗
PubMed1977

Luminal dilatation and morphologic changes secondary to enterotoxins.

Structural changes in ligated rat small intestinal loops exposed to purified cholera enterotoxin are described. Distention secondary to increased luminal fluid was found to cause the artifactual histologic damage. This finding questions the validity of interpreting mucosal changes in closed intestinal-loop models in the presence of severe distention. An alternative open-loop model is described that eliminates distention as a cause of histologic changes.

Animals↗
PubMed1975

The effects of cholera enterotoxin on intestinal tissue water as measured by nuclear magnetic resonance (NMR) spectroscopy.

Cholera enterotoxin has been postulated to change the configuration of the intracellular protein-water system, altering the permeability of the cell to water. Using nuclear magnetic resonance (NMR) spectroscopy, this protein-water relationship can be examined. Small intestinal loops in the rat were injected with 0.5 ml of either Schwarz/Mann cholera enterotoxin (40 mug/cc saline solution) or normal saline. Full thickness segments of intestine from each loop were taken and percentage water (using a gravimetric procedure which includes a correction for fat) and NMR relaxation times were determined. The mean value +/- S.D. for tissue water was 79.49 +/- 2.65% in the controls and 84.52 +/- 2.01% in the cholera specimens (p less than .001). T1 (spin-lattice) relaxation times were 521.22 +/- 69.5 msec in the controls and 667.96 +/- 119.25 msec in cholera tissue (p less than .001). T2 (spin-spin) relaxation times were 62.34 +/- 9.59 msec in controls and 80.35 +/- 21.46 msec in cholera tissue (p less than .02). These findings are consistent with the theory that cholera enterotoxin acts to alter intracellular protein-water relationship.

Animals↗