Hyperventilation and attention: effects of hypocapnia on performance in a stroop task.

This study aimed to investigate the effect of hypocapnia on attentional performance. Hyperventilation, producing hypocapnia, is associated with physiological changes in the brain and with subjective symptoms of dizziness, concentration problems and derealization. In this study (N=42), we examined cognitive performance on a Stroop-like task, following either 3 min of hypocapnic or normocapnic overbreathing. Both overbreathing trials were run on separate days, each preceded by a baseline trial with the same task during normal breathing. More and other symptoms were reported after hypocapnia compared to normocapnia. Also, more errors were made and progressively slower reaction times (RT's) were observed during recovery from hypocapnia. These performance deficits were only found in participants characterized by apneas. The number of symptoms did not correlate with RT's or errors. The pattern of data suggested that hypoxia, as a result of apneas during recovery from hypocapnia, caused the cognitive performance deficit.

Typical and atypical fractures of the odontoid process in young children. Report of two cases and a review of the literature.

The most common injury to the odontoid process in children under the age of seven years is a fracture through the synchondrosis with or without anterior displacement of the odontoid process, but this is not the only type of fracture of the odontoid process in this age-group. Fractures above and below the synchondrosis and fractures with posterior displacement were described. Typical clinical features of these fractures are: (1) major and blunt trauma, (2) neck pain and resistance to active and passive head movements; and (3) no or only slight neurological deficits. Conservative treatment had excellent results in the majority of cases. Nevertheless, there are a few specific indications for surgery.