Dural Venous Sinus Stenosis: Why Distinguishing Intrinsic-versus-Extrinsic Stenosis Matters.

BACKGROUND AND PURPOSE: Dural venous sinus stenosis has been associated with idiopathic intracranial hypertension and isolated venous pulsatile tinnitus. However, the utility of characterizing stenosis as intrinsic or extrinsic remains indeterminate. The aim of this retrospective study was to review preprocedural imaging of patients with symptomatic idiopathic intracranial hypertension and pulsatile tinnitus, classify the stenosis, and assess a trend between stenosis type and clinical presentation while reviewing the frequencies of other frequently seen imaging findings in these conditions. MATERIALS AND METHODS: MRVs of 115 patients with idiopathic intracranial hypertension and 43 patients with pulsatile tinnitus before venous sinus stent placement were reviewed. Parameters recorded included the following: intrinsic or extrinsic stenosis, prominent emissary veins, optic nerve tortuosity, cephalocele, sella appearance, poststenotic fusiform enlargement versus saccular venous aneurysm, and internal jugular bulb diverticula. χ2 cross-tabulation statistics were calculated and recorded for all data. RESULTS: Most patients with idiopathic intracranial hypertension (75 of 115 sinuses, 65%) had extrinsic stenosis, and most patients with pulsatile tinnitus (37 of 45 sinuses, 82%) had intrinsic stenosis. Marked optic nerve tortuosity was more common in idiopathic intracranial hypertension. Cephaloceles were rare in both cohorts, with an increased trend toward the presence in idiopathic intracranial hypertension. Empty sellas were more common in idiopathic intracranial hypertension. Cerebellar tonsils were similarly located at the foramen magnum level in both cohorts. Saccular venous aneurysms were more common in pulsatile tinnitus. Internal jugular bulb diverticula were similarly common in both cohorts. CONCLUSIONS: In this cohort, most patients with idiopathic intracranial hypertension had extrinsic stenosis, and most patients with pulsatile tinnitus had intrinsic stenosis. Awareness and reporting of these subtypes may reduce the underrecognition of potential contributory stenoses in a given patient's idiopathic intracranial hypertension or pulsatile tinnitus.

Nattectin a fish C-type lectin drives Th1 responses in vivo: Licenses macrophages to differentiate into cells exhibiting typical DC function

Considerable efforts are currently focused on the biology of DC in view of their possible clinical use as adjuvant for the generation of antigen-specific immunity and lifelong immunologic memory or for the treatment of tumors. We assessed the role of Nattectin a C-type lectin identified in the Thalassophryne nattereri fish venom in DC maturation. Nattectin induced a significant neutrophilic recruitment into peritoneal cavity of mice, followed by macrophages, with lipidic mediators and IL-12 p70 synthesis. Macrophages derived from 7 day-Nattectin mice were CD11c + CD11blowLy6 highF4/80Rhigh and express high levels of MHC class II and CD80 molecules. Culture of peritoneal exudates derived macrophages from 7 day Nattectin-mice and immature BMDCs with Nattectin markedly increased the surface expression of CD40, CD80, CD86, and MHC class II in a dose-dependent manner, and the production of MMP-2 and MMP-9 distributed in nucleus and cytoplasm of cells, that was associated with strong activity in the culture supernatant. Nattectin treated DCs secreted IL-12 p70 and IL-10. The Nattectin-treated BMDC or macrophage-derived DCs were highly efficient at Ag capture. The specific immune response elicited by Nattectin was characterized by the production of specific antibodies IgG1 and mainly IgG2a with IL-10 and IFN-ã synthesis by splenic cells. These results enable us to address that Nattectin induces the recruitment of Ly6Chigh monocytes into the peritoneum, which exhibit a pro-inflammatory profile, where they differentiate into proliferating F4/80Rhigh macrophages. Macrophage-derived DCs mature in the presence of the cytokine milieu generated against Nattectin, exhibiting T cell co-stimulatory molecule expression and induced a Th1 polarized response.

Yet another application of the Monte Carlo method for modeling in the field of biomedicine.

By means of Monte Carlo simulations performed in the C programming language, an example of scientific programming for the generation of pseudorandom numbers relevant to both teaching and research in the field of biomedicine is presented. The relatively simple algorithm proposed makes possible the statistical analysis of sequences of random numbers. The following three generators of pseudorandom numbers were used: the rand function contained in the stdlib.h library of the C programming language, Marsaglia's generator, and a chaotic function. The statistical properties of the sequences generated were compared, identical parameter values being adopted for this purpose. The properties of two estimators in finite samples of the pseudorandom numbers were also evaluated and, under suitable conditions, both the maximum-likelihood and method of moments proved to be good estimators. The findings demonstrated that the proposed algorithm appears to be suitable for the analysis of data from random experiments, indicating that it has a large variety of possible applications in the clinical practice.

Ocular findings in neonates after extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a modified, prolonged cardiopulmonary bypass procedure used to treat newborns who have reversible cardiac or respiratory failure. The venoarterial bypass technique requires cannulation of both the right carotid artery and the internal jugular vein, and after decannulation these vessels are permanently ligated. Left-sided retinal vascular changes after ECMO have been reported, and were attributed to ligation of these vessels. A retrospective review of the results of ocular examinations of 86 infants who had undergone ECMO therapy at Childrens Hospital in Los Angeles between March, 1987 and May, 1991 was conducted. Normal findings were noted in 73 infants. One infant had bilateral retinal vascular tortuosity, and 12 infants had incidental ocular findings, but there was no evidence of left-sided retinal hemorrhage, venous congestion, or tortuosity. Our results suggest that left-sided retinal vascular changes after ECMO do not occur, occur only rarely, or clear rapidly and result in no permanent retinal damage. To unequivocally rule out the possibility that ECMO can cause transitory retinal vascular changes, we recommend further prospective studies, with ocular examinations performed before, during, and after ECMO.

Pulmonary sequelae at six months following extracorporeal membrane oxygenation.

Mechanical assisted ventilation for neonatal respiratory failure is associated with residual lung disease. Because ECMO rests the lungs, it has been suggested that ECMO will prevent chronic lung disease in survivors. To determine whether or not ECMO survivors have evidence of pulmonary sequelae, we studied 19 infants who were treated with ECMO for neonatal respiratory failure. Ten infants still required supplemental oxygen or pulmonary medications or both to treat clinical lung disease during the first six months of life. Thoracic gas volume was normal. Pulmonary mechanics in ECMO survivors were compared with those of 13 preterm infants with BPD at similar age. We conclude that a significant proportion of ECMO survivors have residual abnormalities in pulmonary mechanics at 6 months of age. We speculate that neonatal lung injury due to meconium aspiration and other causes is a more important determinant of abnormal pulmonary sequelae than the method of treatment.

Serial measurement of pulmonary mechanics assists in weaning from extracorporeal membrane oxygenation in neonates with respiratory failure.

Extracorporeal membrane oxygenation (ECMO) is a highly invasive therapy for intractable neonatal respiratory failure, and serious complications may occur with increasing duration of bypass. Weaning from bypass is empirical at present. Thus, there is a need to accurately predict when infants can be successfully decannulated. We hypothesized that pulmonary mechanics would reflect lung recovery and, therefore, predict successful weaning from ECMO. We measured pulmonary mechanics daily in 22 neonates, at gestational age of 37.8 +/- 0.6 weeks (SE) requiring ECMO for severe respiratory failure (oxygen index 66 +/- 6). Pulmonary resistance (Rpul), dynamic compliance (Cdyn), and tidal volume (VT) were measured. Rpul did not predict lung recovery. Cdyn within 24 hours of starting ECMO was 0.3 +/- 0.04 ml/cm H2O. Cdyn within 24 hours of weaning from ECMO was 1.2 +/- 0.09 ml/cm H2O (p less than 0.001). All 22 infants had Cdyn greater than 0.6 ml/cm H2O at the time of decannulation, but four infants (20 percent) with Cdyn less than 0.6 ml/cm H2O could not be weaned from ECMO within 20 hours (p less than 0.01). Thus, a minimum Cdyn of 0.6 ml/cm H2O is associated with successful weaning from ECMO. Cdyn of 0.8 ml/cm H2O provided better overall discrimination between those who could be successfully weaned from ECMO. We conclude that serial measurement of dynamic pulmonary compliance predicts successful weaning from ECMO.

Capillary plasma ammonia concentration in neonates receiving total parenteral nutrition. Comparison with arterial and venous concentrations.

Plasma ammonia concentration in neonates has routinely been determined using arterial or venous blood. Expected plasma ammonia values in capillary blood obtained by heelstick have not been determined. We compared ammonia levels in 20 sets of plasma from simultaneously drawn arterial, venous, and capillary blood in a group of neonates receiving total parenteral nutrition. Mean ammonia concentrations in venous (107 +/- 44) and capillary blood (112 +/- 33) were 45% and 51% higher, respectively, than corresponding arterial (74 +/- 22) values (P less than .001). Ammonia levels in blood obtained by venipuncture (Ven), however, did not correlate consistently with arterial (Art) values (r = .43; Art = 51 + 0.21 Ven; P greater than .05). In contrast, ammonia levels in capillary blood (Cap) correlated well with arterial values (r = .86; Art = 10.3 + 0.6Cap; P less than .001). Ammonia levels in neonates may be reliably interpreted using the latter regression equation when blood for analysis is obtained by a properly performed heelstick, allowing the preservation of arteries and veins, and sparing the infant from repetitive needle punctures. Ammonia levels in blood obtained by venipuncture do not adequately correlate with arterial values and therefore may be therapeutically misleading.

Childhood sequelae of infant lung disease: exercise and pulmonary function abnormalities after bronchopulmonary dysplasia.

To determine the long-term pulmonary sequelae and effect on exercise tolerance of bronchopulmonary dysplasia (BPD), we studied 10 children at a mean age of 10.4 years, who had been born prematurely, survived respiratory distress syndrome, and subsequently developed BPD, and compared them with eight age-matched normal children born at term. Pulmonary function tests and graded exercise stress tests were performed. Residual volume, the ratio between residual volume and total lung capacity, vital capacity, forced expiratory volume in 1 second, forced expiratory flow between 25% and 75% of vital capacity, and maximal expiratory flows at 80%, 70%, and 60% of total lung capacity were all abnormal (P less than 0.02) in the children with BPD, compared with control values. Pre-exercise transcutaneous CO2 tension was higher (P less than 0.05) in the BPD group than in the control group. At maximal workload, tcPCO2 remained high in patients with BPD compared with control values (P less than 0.05). Arterial oxygen saturation at maximal workload fell below pre-exercise levels in the BPD group (P less than 0.05) but not in control children. There were no differences in maximal oxygen consumption between the BPD group and control children. Exercise-induced bronchospasm occurred in 50% of the BPD group, but not in the control group. We conclude that long-term survivors of BPD have evidence of airway obstruction, hyperinflation, and airway hyperreactivity, compared with a control group. Aerobic fitness was not significantly different in the BPD and control groups, but was achieved in the BPD group at the expense of a fall in SaO2 and a rise in tcPCO2.

Unexpected hearing loss in high-risk infants.

Eleven high-risk infants who had normal auditory brainstem responses at the time of discharge from the neonatal intensive care unit were found on follow-up between 13 and 48 months later to have significant sensorineural hearing loss. All 11 infants were the products of high-risk pregnancies and deliveries. Birth weights ranged from 890 to 3,700 g, but seven had birth weights of more than 1,500 g. Gestational ages ranged from 28 to 42 weeks. The length of hospitalization ranged from 45 to 167 days. All of the infants had respiratory distress, requiring prolonged mechanical ventilation with resultant chronic lung disease. All of the infants had received pancuronium, morphine, ampicillin, and gentamicin, and ten had also received furosemide and chlorothiazide. Other frequent clinical complications included abnormal CNS findings during the neonatal intensive care unit stay (ten infants), acidosis (pH less than 7.25) on the initial blood gas test (eight infants), and persistent fetal circulation in all seven infants with birth weights greater than 1,500 g. Developmentally, eight of nine children tested between 12 and 36 months of age were normal in all respects other than the hearing loss and the related language impairment. We conclude that infants who have been very ill in the newborn period, including term infants, may remain at risk for development of significant sensorineural hearing loss even though they have passed an initial auditory brainstem responses screening test in the newborn period.

Management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant with a subcutaneous ventricular catheter reservoir.

To control hydrocephalus resulting from massive intraventricular hemorrhage in premature neonates with respiratory distress syndrome, we inserted a specially designed low profile subcutaneous ventricular catheter reservoir (reservoir) by the 12th day of life (average; range, 3 to 30 days) in 20 neonates whose mean birth weight was 1110 +/- 270 g (28.7 +/- 1.6 weeks of gestation). The reservoir was repeatedly aspirated over 10 to 48 days. No cerebrospinal fluid infection, reservoir obstruction, or breakdown of the skin overlying the reservoir occurred. Serial computed tomographic scans documented control of the hydrocephalus and an increase in the thickness of the cortical mantle of the survivors. No mortality was associated with placement of the reservoir or its subsequent conversion, if necessary, to a ventriculoperitoneal shunt. However, only 7 of the 20 infants survived. On follow-up 3 to 5 years later, 2 of the 7 have normal intellectual and motor development. Two infants are normal intellectually, but have a motor deficit. The remaining 3 patients have both significant intellectual and motor developmental delay. The use of the reservoir is offered as a safe and effective alternative to repeated ventricular punctures, external ventricular drainage, or initial shunting. Aggressive management of hydrocephalus secondary to intraventricular hemorrhage may improve neurological function in some surviving neonates.

Negative pressure artificial respiration: use in treatment of respiratory failure of the newborn.

Ninety-one infants with respiratory failure secondary to primary pulmonary disease and with a birth weight of 1000 g. or over have been managed in a negative-pressure respirator (Air-Shields) over a three-year period. Of these the failure in 87 was due to respiratory distress syndrome (RDS) and in four it resulted from massive meconium aspiration. Respiratory failure was indicated initially by arterial blood gas tensions (while breathing 100% O(2)) of Po(2) <40 mm. Hg, pH <7.10 and Pco(2) >75 mm. Hg in the initial 47 cases; these levels were subsequently raised to Po(2) < 50 mm. Hg, pH <7.20 and Pco(2) >70 mm. Hg for the remainder. Fifty-four (59.3%) of the infants survived the use of the respirator and 47 of these (51.6%) were subsequently discharged alive and well. Mean time in hours to normalization of blood gas values while on the respirator were as follows: for Po(2), 10.5; for pH, 11.6; and for Pco(2), 22.6. These values indicate that the respirator is more efficient in promoting oxygenation (raising Po(2)) than ventilation (lowering Pco(2)). They also suggest that the observed acidosis is in large part secondary to the hypoxia rather than the result of co(2) retention. For the survivors the average time of total respirator dependency before commencement of weaning was 53.7 hours. All the infants were managed without the use of endotracheal tubes although the use of the respirator and/or administration of 100% oxygen were either continuous or intermittent for periods of up to two weeks. There have been no instances of so-called respirator lung disease in the survivors or in those who died, which suggests that the use of high oxygen concentration by itself is not the major factor in the pathogenesis of this complication.