Recruitment of anterior dorsolateral prefrontal cortex in human reasoning: a parametric study of relational complexity

Reasoning and problem solving depend on the ability to represent and integrate complex relationships among stimuli. For example, deciding whether an animal is dangerous requires integrating information about the type of animal, its size, its distance from oneself, and one's proximity to shelter. Relational complexity increases with the number of such interdependent elements that must be simultaneously considered to solve a problem. We used functional magnetic resonance imaging to identify brain regions that respond selectively in processing high levels of relational complexity. Performance on nonverbal reasoning problems in which relational complexity was varied parametrically was compared with performance on control problems in which relational complexity was held constant while difficulty was manipulated by adding distractor forms to the problems. Increasing complexity and adding distractors both led to increased activation in parietal and in dorsolateral prefrontal cortex, with high levels of relational complexity selectively activating anterior left prefrontal cortex. Our data provide evidence that brain regions specific to integrating complex relations among stimuli are distinct from those involved in coping with general task difficulty and with working-memory demands.     

Results of laparoscopic antireflux procedures in neurologically normal infants and children

Most children treated for gastroesophageal reflux have been neurologically impaired. With the recent growth of laparoscopic surgery, neurologically normal children are being referred for fundoplication. We review the presentation diagnostic workup and surgical therapy for children with gastroesophageal reflux unresponsive to medical management. Although many techniques are available for surgical correction of gastroesophageal reflux in children, the laparoscopic Nissen fundoplication remains the standard for correction of gastroesophageal reflux. The technique is performed through five trocars, and emphasis is placed on obtaining at least 3 cm of intra-abdominal esophagus and holding the esophagus in this position with sutures between the crura and the esophagus. The fundoplication should be loose and no longer than 2 cm in length. Long-term follow-up has shown recurrence to be low in children who are neurologically normal as long as they do not gag and retch recurrently.     

Flexion-distraction injuries in the thoracolumbar spine: an in vitro study of the relation between flexion angle and the motion axis of fracture

A new concept, the motion axis of fracture (MAF), which is defined as the transitional point from anterior compressive to posterior splitting failure on a lateral radiograph, has provided a true understanding of the mechanisms of flexion-distraction injuries in clinical cases. This study was designed to produce in vitro injuries that have MAFs and to clarify the relation between the flexion angle and the MAF location. Adolescent porcine thoracolumbar spines were exposed to a vertical compressive load to failure at three different flexion angles and then examined radiographically. The MAF location was recorded as the distance from the anterior border to the MAF expressed as a percentage of the anteroposterior diameter of the vertebral body. All specimens showed similar injuries, with MAFs consisting of anterior compression fractures in the vertebral bodies and posterior disruptions. A significant negative correlation emerged between the flexion angle and the MAF location (r = -0.890; p < 0.0001). These results suggest that even a vertical compressive load contributes to the production of a flexion-distraction injury with an MAF in the thoracolumbar spine. They also indicate that the flexion angle of the spine at which the vertical compressive load is applied is an important factor in determining the MAF location; that is, the larger the flexion angle, the more anterior the MAF.     

Does anterior plating maintain cervical lordosis versus conventional fusion techniques? A retrospective analysis of patients receiving single-level fusions

A retrospective review of medical records and radiographs of patients receiving anterior cervical discectomy and fusion (ACDF) without anterior plating and with anterior plating was performed. The objective of the study was to determine whether a difference exists in cervical lordotic alignment between subjects undergoing single-level ACDF with and without anterior cervical plating instrumentation for symptomatic cervical disc disease. Collapse or settling of grafted bone into the vertebral endplates with resulting kyphotic deformity of the cervical spine is a commonly described complication of anterior discectomy and fusion. Despite the increasing use of instrumentation for the treatment of cervical spine injuries and degenerative conditions, little is known regarding lordotic alignment of the cervical spine in patients who receive plating instrumentation compared with conventional fusion without plating. Accumulating evidence suggests that plating is superior to non-plating techniques in patients with multiple level cervical disc lesions in regard to fusion, return to work rates, and complication rates; however, little is known about maintenance of lordotic curve alignment in single- and multiple-level procedures. Neutral lateral cervical radiographs of 57 patients who underwent single-level ACDF between 1994 and 1999 with anterior screw plates (n = 26), and conventional single-level fusion without anterior screw plates (n = 21) were retrospectively assessed. Measurements were made on weight-bearing lateral cervical radiographs to assess overall sagittal spinal alignment and intersegmental sagittal alignment at the surgical site before surgery, immediately after surgery, 4 to 12 weeks after surgery, and 12+ months after surgery. The average magnitude of overall lordosis measured between C2 and C7 decreased 4.2 degrees in the non-plated group, while being preserved in the plated group. This finding did not reach statistical significance in the long-term follow-up. At the surgical site, the segmental contribution to lordosis decreased an average 2.5 degrees in the non-plated group versus an increase of 5.67 degrees in the plated group, and this finding was statistically significant between groups measured at all pre- and postoperative visits (p < 0.01). On average, the plating procedure resulted in preserving overall lordosis while increasing the magnitude of segmental lordosis at the surgical site. In comparison, the conventional method resulted in a net loss of overall lordosis and segmental lordosis at the surgical site.     

Bronchiectasis in indigenous children in remote Australian communities

The rates of bronchiectasis for Indigenous children from remote Australian communities are unacceptably high, with one study showing 14.7/1000 Aboriginal children. Children with bronchiectasis need to be identified early for optimisation of medical treatment. Under-reporting of cough is common. Bronchiectasis should be suspected in children with recurrent bronchitis or pneumonia, and when, despite appropriate therapy, pulmonary infiltrates or atelectasis persist 12 weeks beyond the index illness. During acute infective episodes, oral antibiotics and chest physiotherapy to clear the airways should produce prompt resolution; otherwise, hospitalisation is necessary. Management follows the cystic fibrosis model of regular review, encouragement of physical activity, optimising nutrition, maintenance of immunisation and avoidance of environmental toxicants, including passive smoke exposure. Successful management and prevention of bronchiectasis will require improvements in housing, nutrition, and education, as well as access to comprehensive healthcare services, with coordination between primary and hospital-based healthcare providers.     

The Multilevel Structure of Four Adolescent Problems

This paper examines variability in adolescent self-reported behavior at the individual, cohort, and school levels for 8th and 11th graders. We examine four adolescent behaviors: substance use, antisocial behavior, depression, and academic performance. Research staff collected the data as part of the Oregon Healthy Teens survey of a population-based sample of 60,837 adolescents over three years in 92 communities. The results indicate that schools vary over time, but not necessarily systematically, and grade-level cohorts account for important variance within schools. The school and cohort combined, however, accounted for at most 4% of the overall variance. The results have implications for research and practice in schools and communities. For example, selection of communities for interventions based on high levels of adolescent problems may be unproductive if individuals account for at least 96% of the variance. Furthermore, in non-experimental designs, cohort variability, not an intervention, may account for apparent improvement across