Is the search for right-to-left shunt still worthwhile?

OBJECTIVES: Patent foramen ovale (PFO) is a common disembryogenic defect with well-attested prevalence but dubious etiopathogenetic linkage with cryptogenic stroke and different clinical conditions. Transcranial color-coded Doppler (TCCD) assures high accuracy in diagnosing right-to-left shunt (RLS) and its functional aspects. Aim of the study was to evaluate RLS prevalence and degree in subjects submitted to TCCD for conditions theoretically associated or caused by paradoxical embolism to the brain. METHODS: PFO assessment, performed in 10 major diagnostic categories and a control group, followed a standardized protocol with a 10 or 20 microbubbles (MB) cutoff to identify any or only large RLS, respectively. RESULTS: Among 2113 patients, a significant larger RLS prevalence was found in stroke (53.3%), TIA (45.7%) and migraine with aura (39.7%) when compared with non-migraineurs controls (25.5%). RLS degree was significantly higher in stroke and TIA patients: The ROC curve from MB load data helped to identify new cutoff values for both normal breathing (42 MB) and Valsalva (139 MB) tests. From logistic regression, a family history for PFO, ASA, and male gender appeared independent predictors of a RLS. By contrast, RLS seemed independent of white matter abnormalities presence on brain neuroimaging or stroke mimics. CONCLUSIONS: In addition to recently defined criteria, genetically determined inheritable traits and epidemiologic characteristics (male gender) should be taken into account when assessing PFO and related cerebrovascular risk profile. A newly defined threshold in TCCD MB count is suggested to discriminate shunts related to stroke and TIA from innocent ones.

Short-term effects on postural control can be evidenced using a seesaw.

Postural control strategies are frequently assessed through posturography on a firm surface. Their motor efficiency is related to the coordination between center-of-gravity (CG) and center-of-pressure (CP) movements, which results from long-term training. However, when standing on a seesaw favoring pitching body motions, a new coordination, requiring short-term training, needs to be learned again. On this type of device, somesthetic cues from the ankle joints become invalid and motor command is amplified because of the curvature of the contact ridges. To highlight the mechanisms involved in short-term improvements of postural control, 11 healthy young adults were trained for 20 min by standing on a seesaw with their eyes closed. Two series of posturographic measurements, before and after the training, were recorded whilst the subjects stood on the seesaw with eyes closed. The results indicate a reduction in the horizontal CG displacements along the anteroposterior axis and CP-CG displacements along both anteroposterior and mediolateral axes. Fractional Brownian motion (fBm) analysis further explains these lessened CG movements by highlighting a reduced distance covered before the corrective mechanisms take over. The other fBm parameters, the contribution of stochastic activity during the shortest and longest time intervals or the time interval of the transition points (which expresses the mean delay before the corrective mechanisms take over), remained unchanged. These results could likely be explained by reduced tonic muscular activity of the lower limbs and/or recalibration of the sensory systems in order to improve the detection of the CG movements.