Ultrasound Examination and Localization of the Sciatic Nerve: A Volunteer Study

Background: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.     

Antenatal steroid therapy: have we undervalued the risks?

Antenatal corticosteroid therapy to enhance fetal lung maturation in pregnancies at risk for preterm delivery is used commonly, based on the assumption that its established benefits outweigh associated risks. Corticosteroid treatment does confer some risks, particularly with respect to restricted brain growth and disordered neuronal development. These alterations have the potential for long-term effects on health. They deserve further study, and should not be undervalued. Corticosteroid therapy should be applied selectively in those situations in which the risk of preterm birth is very high and the likelihood of severe respiratory distress syndrome substantial.     

Penicillium piceum infection: diagnosis and successful treatment in chronic granulomatous disease.

Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.     

Investigation of the phenylalanine hydroxylase gene and tardive dyskinesia.

Phenylketonuria (PKU), an inborn error of phenylalanine metabolism, has been shown to be a risk factor for tardive dyskinesia (TD). In male psychiatric patients there was a significant relationship between TD and measures of plasma phenylalanine following ingestion of a standardized phenylalanine dose that was indicative of higher brain availability of phenylalanine in patients with TD. In addition, a medical food formulation consisting of branched chain amino acids, which compete with phenylalanine for transport across the blood-brain barrier, has been demonstrated to be an efficacious treatment for TD. Cumulatively these findings suggested that TD was related to phenylalanine metabolism and thus that sequence variants in the gene for phenylalanine hydroxylase (PAH), the rate-limiting enzyme in the catabolism of phenylalanine, could be associated with TD susceptibility. Genetic screening of PAH in a group of 123 psychiatric patients revealed ten sequence polymorphisms and two mutations, but none appeared to be a significant risk factor for TD.     

Mode of Delivery and the Survival of Macrosomic Infants in the United States, 1995–1999

ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)     

A review of the effectiveness of aspartame in helping with weight control

Summary Strategies to reverse the upward trend in obesity rates need to focus on both reducing energy intake and increasing energy expenditure. The provision of low‐ or reduced‐energy‐dense foods is one way of helping people to reduce their energy intake and so enable weight maintenance or weight loss to occur. The use of intense sweeteners as a substitute for sucrose potentially offers one way of helping people to reduce the energy density of their diet without any loss of palatability. This report reviews the evidence for the effect of aspartame on weight loss, weight maintenance and energy intakes in adults and addresses the question of how much energy is compensated for and whether the use of aspartame‐sweetened foods and drinks is an effective way to lose weight. All studies which examined the effect of substituting sugar with either aspartame alone or aspartame in combination with other intense sweeteners on energy intake or bodyweight were identified. Studies which were not randomised controlled trials in healthy adults and which did not measure energy intakes for at least 24 h (for those with energy intakes as an outcome measure) were excluded from the analysis. A minimum of 24‐h energy intake data was set as the cut‐off to ensure that the full extent of any compensatory effects was seen. A total of 16 studies were included in the analysis. Of these 16 studies, 15 had energy intake as an outcome measure. The studies which used soft drinks as the vehicle for aspartame used between 500 and about 2000 ml which is equivalent to about two to six cans or bottles of soft drinks every day. A significant reduction in energy intakes was seen with aspartame compared with all types of control except when aspartame was compared with non‐sucrose controls such as water. The most relevant comparisons are the parallel design studies which compare the effects of aspartame with sucrose. These had an overall effect size of 0.4 standardised difference (SD). This corresponds to a mean reduction of about 10% of energy intake. At an average energy intake of 9.3 MJ/day (average of adult men and women aged 19–50 years) this is a deficit of 0.93 MJ/day (222 kcal/day or 1560 kcal/week), which would be predicted (using an energy value for obese tissue of 7500 kcal/kg) to result in a weight loss of around 0.2 kg/week with a confidence interval 50% either side of this estimate. Information on the extent of compensation was available for 12 of the 15 studies. The weighted average of these figures was 32%. Compensation is likely to vary with a number of factors such as the size of the caloric deficit, the type of food or drink manipulated, and timescale. An estimate of the amount of compensation with soft drinks was calculated from the four studies which used soft drinks only as the vehicle. A weighted average of these figures was 15.5%. A significant reduction in weight was seen. The combined effect figure of 0.2 SD is a conservative figure as it excludes comparisons where the controls gained weight because of their high‐sucrose diet and the long‐term follow‐up data in which the aspartame groups regained less weight than the control group. An effect of 0.2 SD corresponds to about a 3% reduction in bodyweight (2.3 kg for an adult weighing 75 kg). Given the weighted average study length was 12 weeks, this gives an estimated rate of weight loss of around 0.2 kg/week for a 75‐kg adult. The meta‐analyses demonstrate that using foods and drinks sweetened with aspartame instead of sucrose results in a significant reduction in both energy intakes and bodyweight. Meta‐analyses both of energy intake and of weight loss produced an estimated rate of weight loss of about 0.2 kg/week. This close agreement between the figure calculated from reductions in energy intake and actual measures of weight loss gives confidence that this is a true effect. The two meta‐analyses used different sets of studies with widely differing designs and controls. Although this makes comparisons between them difficult, it suggests that the final figure of around 0.2 kg/week is robust and is applicable to the variety of ways aspartame‐containing foods are used by consumers. This review has shown that using foods and drinks sweetened with aspartame instead of those sweetened with sucrose is an effective way to maintain and lose weight without reducing the palatability of the diet. The decrease in energy intakes and the rate of weight loss that can reasonably be achieved is low but meaningful and, on a population basis, more than sufficient to counteract the current average rate of weight gain of around 0.007 kg/week. On an individual basis, it provides a useful adjunct to other weight loss regimes. Some compensation for the substituted energy does occur but this is only about one‐third of the energy replaced and is probably less when using soft drinks sweetened with aspartame. Nevertheless, these compensation values are derived from short‐term studies. More data are needed over the longer term to determine whether a tolerance to the effects is acquired. To achieve the average rate of weight loss seen in these studies of 0.2 kg/week will require around a 220‐kcal (0.93 MJ) deficit per day based on an energy value for obese tissue of 7500 kcal/kg. Assuming the higher rate of compensation (32%), this would require the substitution of around 330 kcal/day (1.4 MJ/day) from sucrose with aspartame (which is equivalent to around 88 g of sucrose). Using the lower estimated rate of compensation for soft drinks alone (15.5%) would require the substitution of about 260 kcal/day (1.1 MJ/day) from sucrose with aspartame. This is equivalent to 70 g of sucrose or about two cans of soft drinks every day.