Postural control and head stability during natural gaze behaviour in 6- to 12-year-old children.

We investigated how the influence of natural exploratory gaze behaviour on postural control develops from childhood into adulthood. In a cross-sectional design, we compared four age groups: 6-, 9-, 12-year-olds and young adults. Two experimental trials were performed: quiet stance with a fixed gaze (fixed) and quiet stance with natural exploratory gaze behaviour (exploratory). The latter was elicited by having participants watch an animated short film on a large screen in front of them. 3D head rotations in space and centre of pressure (COP) excursions on the ground plane were measured. Across conditions, both head rotation and COP displacement decreased with increasing age. Head movement was greater in the exploratory condition in all age groups. In all children-but not in adults-COP displacement was markedly greater in the exploratory condition. Bivariate correlations across groups showed highly significant positive correlations between COP displacement in ML direction and head rotation in yaw, roll, and pitch in both conditions. The regularity of COP displacements did not show a clear developmental trend, which indicates that COP dynamics were qualitatively similar across age groups. Together, the results suggest that the contribution of head movement to eye-head saccades decreases with age and that head instability-in part resulting from such gaze-related head movements-is an important limiting factor in children's postural control. The lack of head stabilisation might particularly affect children in everyday activities in which both postural control and visual exploration are required.

[Cholesteatoma: rare, but can have serious consequences]. / Cholesteatoom.

Cholesteatoma is a mass formed by the keratinizing squamous epithelium in the tympanic cavity and/or mastoid that can lead to the destruction of surrounding structures in the ear. It can arise at any age. Symptoms are non-specific and diagnosis may be difficult on otoscopic examination. The management of cholesteatoma is surgical; mastoid obliteration has reduced the incidence of recurrent cholesteatoma in recent years. The use of diffusion-weighted MRI has proven to be a reliable technique for the detection and follow-up of cholesteatoma.

[Elderly women with abdominal pain due to an incarcerated 'femoral hernia']. / Oudere vrouwen met buikpijn door een beklemde 'dijbreuk'.

Symptoms and findings during physical examination of patients with a femoral hernia are notoriously aspecific. Signs in the inguinal region tend to be overlooked, particularly in obese patients. Three women aged 72, 83 and 68, presented with abdominal pain and ileus due to incarcerated femoral hernias. A correct diagnosis was not considered prior to emergency laparotomy. One progressively septic patient with disseminated breast cancer refused reintervention after successful correction of the femoral hernia, and succumbed. The other two recovered uneventfully. Any older female patient with recurrent abdominal complaints may harbour a femoral hernia. The inguinal region should be examined, if possible in the upright position. Ultrasound, CT or MRI scans should establish the diagnosis. Open or laparoscopic intervention is required in patients fit for surgery since incarceration of a femoral hernia is associated with considerable morbidity and even mortality.

Basketball jump shooting is controlled online by vision.

An experiment was conducted to examine whether basketball jump shooting relies on online visual (i.e., dorsal stream-mediated) control rather than motor preprogramming. Seventeen expert basketball players (eight males and nine females) performed jump shots under normal vision and in three conditions in which movement initiation was delayed by zero, one, or two seconds relative to viewing the basket. Shots were evaluated in terms of both outcome and execution measures. Even though most shots still landed near the basket in the absence of vision, end-point accuracy was significantly better under normal visual conditions than under the delay conditions, where players tended to undershoot the basket. In addition, an overall decrease of inter-joint coordination strength and stability was found as a function of visual condition. Although these results do not exclude a role of motor preprogramming, they demonstrate that visual sensory information plays an important role in the continuous guidance of the basketball jump shot.

The influence of gaze behaviour on postural control from early childhood into adulthood.

In the present study we aimed to track the influence of natural gaze behaviour on postural control from early childhood into adulthood. We measured time series of centre of pressure (COP) as well as head movement in three children groups aged around five (n=16), eight (n=15), and eleven (n=14) and in one group of young adults (n=15) during quiet stance with eyes closed, gaze fixed on a dot, and with gaze shifts between two dots. We adopted magnitude and irregularity of COP displacement as indexes of postural control and cross correlation between COP displacement and target oscillation as an index of the dynamical coupling between the postural and visual systems. Magnitude and irregularity of COP displacement decreased with age, which suggests a steady improvement of postural control from five to beyond eleven years of age. Cross correlations were weak and relative phases highly variable across age groups. Across conditions, and most prominently in the gaze shift conditions, 5-year-olds showed both more head movement and lower postural stability than other age groups. Finally, only in 5-year-olds did we find a marked deterioration of postural stability with gaze shifts. We thus conclude that excessive head movement, particularly during gaze shifts, may be a primary cause of lower postural stability in young children compared to older children and adults.