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Biomedical subjects

W C Allan

Publications and source records attributed to W C Allan.

33 records · Page 2Linked to original sources
PubMed1991

Posthemorrhagic hydrocephalus. Use of an intravenous-type catheter for cerebrospinal fluid drainage.

STUDY OBJECTIVE: To report a 9-year experience with the treatment of posthemorrhagic hydrocephalus (PHH) with the use of an easily inserted external ventricular drain. DESIGN: A case series with a retrospective review of hospital records and cranial ultrasound results, from 1981 through 1989, in all infants with PHH. INTERVENTION: A previously defined method of identification and bedside management of PHH was applied. If infants reached 2 kg of body weight and PHH recurred, a ventriculoperitoneal shunt was inserted. RESULTS: A total of 70 procedures were performed in 24 patients, and all were associated with a decrease in head circumference and ventricular size on ultrasound scan. One infection occurred, and only 12 infants required a ventriculoperitoneal shunt. CONCLUSIONS: This technique compared favorably with other methods of intervention to avoid early placement of a ventriculoperitoneal shunt in preterm infants and offered the advantage of consistently decreasing ventricular size. A multicenter-controlled trial will be needed to compare the safety and efficacy of therapies for PHH.

Body Weight↗
PubMed1991

Does cesarean section protect against intraventricular hemorrhage in preterm infants?

A declining incidence of periventricular-intraventricular hemorrhage (PV-IVH) in preterm infants less than 35 weeks' gestational age during the years 1980 through 1987 led us to investigate the role of the route of delivery. Routine cephalic ultrasound was used to detect PV-IVH in 490 vaginal and 411 cesarean section deliveries. A lower incidence of all PV-IVH and severe PV-IVH was noted in cesarean section deliveries for each 2-year period, with a decline in all PV-IVH in vaginal and cesarean section deliveries from 39% and 31%, respectively, in 1980-1981 to 23% and 11% in 1986-1987. Striking differences were noted for infants less than 1500 g, less than 1000 g, or less than 27 weeks' gestation. For example, in infants less than 1000 g, the incidence of all PV-IVH was 52% in vaginal (n = 101) and 25% in cesarean section deliveries (n = 88), and of severe PV-IVH was 26% and 11%, respectively. These differences did not seem to be influenced by presence or absence of labor, breech presentation, or low Apgar scores. Route of delivery should be considered as an important variable in pharmacologic intervention studies.

Cerebral Hemorrhage↗
PubMed1990

The IVH complex of lesions: cerebrovascular injury in the preterm infant.

The term intraventricular hemorrhage has become associated with a variety of cerebrovascular insults in preterm infants. Because of a shared pathophysiology and timing, these are the neurologic lesions to search for when evaluating sick preterm infants. This complex of lesions is common and, when parenchymal injury occurs, likely to result in neurologic sequelae. A review of the variety of injuries, their pathophysiology, their diagnosis by cranial ultrasonography, and their prognosis is offered. Emphasis is placed on the need for assessment over time when evaluating parenchymal lesions in preterm infants.

Cerebral Hemorrhage↗
PubMed1989

Intraventricular hemorrhage.

A review of the role of ultrasound imaging in the diagnosis and study of intraventricular hemorrhage is presented. The characteristics of both early and late scans of germinal matrix, intraventricular, and intraparenchymal hemorrhage, as well as periventricular leukomalacia, have been worked out over the past decade. There is good agreement between the images and pathologic findings. A system of classification that recognizes the importance of parenchymal lesions and their evolution is suggested. The ability to perform repeated ultrasound examinations of sick premature infants has allowed the gathering of important information about pathophysiology, natural history, and outcome. In turn, these studies allow better interpretation of ultrasound scans in the individual infant. Using sequential scans when parenchymal lesions are found improves prognostic information. Prevention of intraventricular hemorrhage is still a goal. However, judging from the experience at our institution it may be that the subtle application of principles demonstrated by the study of this problem with ultrasound imaging has already begun to prevent intraventricular hemorrhage in some patients.

Cerebral Hemorrhage↗
PubMed1989

Intraventricular hemorrhage in preterm infants: declining incidence in the 1980s.

Ultrasound has been routinely used since late 1979 to diagnose periventricular-intraventricular hemorrhage in infants whose gestational age was 34 weeks or less. During the years 1980 to 1987 the ultrasound scans were interpreted by one person, and a steady decline in incidence of periventricular-intraventricular hemorrhage was observed. Both for infants of 34 weeks or less and for very low birth weight (less than 1500 g) infants, periventricular-intraventricular hemorrhage incidence decreased, respectively, from 34% and 39% in 1980 to 1981 to 19% and 25% in 1986 to 1987. This decrease was confined to true intraventricular hemorrhages, which decreased from 22% in 1980 to 1981 to 7% in 1986 to 1987 for infants of less than or equal to 34 weeks' gestation. These results were not influenced by a change in the distribution of birth weights or gestational ages of the infants evaluated nor by a change in the inborn to outborn ratio. The incidence of periventricular-intraventricular hemorrhage was lower in infants born by cesarean section than those delivered vaginally, but the decrease could not be attributed to an increased number of deliveries by cesarean section. Although there were undoubtedly changes in neonatal care during this time period, no planned intervention occurred. It was concluded that pharmacologic intervention studies must be interpreted with caution.

Cerebral Hemorrhage↗
PubMed1986

Periventricular-intraventricular hemorrhage.

This article reviews the pathophysiology of PV-IVH, the clinical aspects, the means of establishing the diagnosis, and the problem of posthemorrhagic ventricular dilation. The most recent advances are emphasized.

Animals↗
PubMed1985

Neonatal cerebral pathology diagnosed by ultrasound.

This article discusses cranial ultrasonography in various clinical settings. Since 1979, the authors have screened all preterm infants for intracranial hemorrhage, and here they present their experience with hemorrhage and its sequel, ventricular dilatation. Also discussed is the use of cranial ultrasonography in infants with seizures and encephalopathy and in infants with abnormal head growth or suspected cerebral malformations.

Cerebral Hemorrhage↗
PubMed1984

Ventricular dilation following periventricular-intraventricular hemorrhage: outcome at age 1 year.

Ventricular dilation following periventricular-intraventricular hemorrhage can be managed without ventriculoperitoneal shunting in most cases. Twenty-six patients who had periventricular-intraventricular hemorrhage with subsequent ventricular dilation were examined at 1 year of age for neurodevelopmental outcome and hydrocephalus. As previously reported, ventricular dilation may be divided into two groups: ventriculomegaly and posthemorrhagic hydrocephalus. Fourteen patients with ventriculomegaly were followed up with serial ultrasound observations only, and 12 patients with posthemorrhagic hydrocephalus had temporary drainage of ventricular fluid. Only three patients with posthemorrhagic hydrocephalus required ventriculoperitoneal shunting in the neonatal period. Neurodevelopmental abnormalities were found in eight infants who had posthemorrhagic hydrocephalus and two who had ventriculomegaly. Six of these infants had intraparenchymal injury demonstrated by ultrasound, five as a result of the original hemorrhage and 1 by infection. A single infant with posthemorrhagic hydrocephalus, discharged from the hospital with stable ventricular size, developed hydrocephalus and neurodevelopmental delay after the neonatal period. This reversed with ventriculoperitoneal shunting at 1 year of age. It is suggested that even in patients developing ventricular dilation following periventricular-intraventricular hemorrhage, it is the primary intraparenchymal injury that is responsible for subsequent morbidity. Thus, provided serial reevaluations are possible, an expectant management of ventricular dilation is justified.

Cerebral Hemorrhage↗
PubMed1982

Ventricular dilation after neonatal periventricular-intraventricular hemorrhage. Natural history and therapeutic implications.

Infants with periventricular-intraventricular hemorrhage (PV-IVH) were followed up with weekly ultrasound sector scans to define the natural history of late ventricular dilation (ie, dilation in excess of that seen at the time of diagnosis of PV-IVH). Infants fell into two groups: (1) posthemorrhagic hydrocephalus (PHH), dilation that produced an increase in occipitofrontal circumference greater than 2 cm per week and/or clinical symptoms of increased intracranial pressure; and (2) ventriculomegaly (VM), dilation that stabilized or reversed without producing these effects. The former was directly related to the severity of hemorrhage. The diameter of the lateral ventricle was significantly greater in PHH. In 26 of 48 infants at risk, late dilation developed: 14 had VM and 12 had PHH. Thus, late ventricular dilation stabilized or resolved spontaneously in 54%. Only three infants eventually required a ventriculoperitoneal shunt. Clinical changes in addition to ventricular size should be used in assessing the need for treatment of ventricular dilation after PV-IVH.

Cerebral Hemorrhage↗
PubMed1980

Sector scan ultrasound imaging through the anterior fontanelle. Its use in diagnosing neonatal periventricular-intraventricular hemorrhage.

The ultrasound sector scanner was used to visualize intracranial pathologic conditions in neonates. The scan head is small enough to make good contact with the anterior fontanelle of infants as small as 700 to 800 g. Clotted blood is clearly seen as a white, echo-dense area, and the scan quality approaches that of computerized tomographic (CT) scan in neonates with intracranial hemorrhage. Three cases were analyzed with CT scan or by autopsy correlation of sector scans. Clinical applications include the diagnosis of periventricular-intraventricular hemorrhage, posthemorrhagic hydrocephalus, and other intracranial pathologic conditions. The use of ultrasound in the diagnosis of neonatal intracranial hemorrhage is briefly reviewed.

Cerebral Hemorrhage↗
PubMed1980

Failure of daily lumbar punctures to prevent the development of hydrocephalus following intraventricular hemorrhage.

A prospective study of 48 infants with periventricular-intraventricular hemorrhage was carried out to evaluate the role of daily lumbar punctures, instituted from the time of diagnosis of the hemorrhage, in prevention of posthemorrhagic hydrocephalus and improvement in immediate outcome. The data lead to the following conclusions: (1) minor hemorrhage (Grade I) is associated with minimal risk of death or hydrocephalus; (2) moderate hemorrhage (Grade II) is associated with low risk of death and intermediate risk of hydrocephalus, and serial lumbar punctures do not reduce these risks; and (3) severe hemorrhage (Grade III) is associated with high risks of death or hydrocephalus or both, and serial lumbar punctures also do not reduce these risks.

Brain↗
PubMed1979

Reduction of cholesterol synthesis by methylxanthines in cultured glial cells.

Methylxanthines are shown in this study to decrease cholesterol synthesis in cultured C-6 glial cells. Aminophylline (10(-3) M) produced a rapid decline in cholesterol synthesis so that by 6 hr, synthesis in treated cells was less than 20% of that in untreated cells, and by 24 hr, less than 10%. Aminophylline induced parallel changes in 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity, the rate-limiting enzyme in cholesterol synthesis. Theophylline and caffeine produced similar effects. Thus, methyxanthines caused a specific, enzyme-mediated reduction in cholesterol synthesis in C-6 glial cells to the developing nervous system, cholesterol synthesis was studied in the presence of 10(-4)M aminophylline. This represents a theophylline concentration in the culture medium that is of the same order of magnitude as that produced in whole brain of animals administered therapeutic doses of aminophylline. Under these conditions, cholesterol synthesis was reduced to approximately 60% of control after 48 and 72 hr.

Aminophylline↗
PubMed1978

Total blindness after trivial frontal head trauma: bilateral indirect optic nerve injury.

A 10-year-old girl developed bilateral blindness and partial third nerve paresis immediately following a closed head injury. Bilateral optic atrophy developed subsequently. This is the first report of an association between second and third nerve injuries after minor head trauma in the absence of a preexisting lesion. The pathophysiology of indirect injury to the optic nerve under these circumstances is uncertain, but the lesions in this patient seemed to be due to ischemia.

Blindness↗
PubMed1977

Ventricular dilation preceding rapid head growth following neonatal intracranial hemorrhage.

We describe two patients in whom ventricular dilation began within a week of neonatal intraventricular hemorrhage and preceded rapid head growth and clinical signs of increased intracranial pressure by days to weeks. The posthemorrhagic ventricular dilation is readily demonstrated in the neonatal period by computerized tomography of the cranium. These data indicate the importance of careful follow-up of survivors of intraventricular hemorrhage, early demonstration of ventricular dilation and prompt therapeutic intervention to prevent brain injury.

Cephalometry↗