To investigate the relevance of lacking or diminished visual input on the expression of migraine, we evaluated its prevalence and clinical features in a population of visually impaired subjects. Between September 1999 and April 2000, 203 visually impaired subjects with a headache inventory were surveyed. Those with headache were assessed according to IHS criteria for the presence of migraine. Migraineurs had their symptoms further detailed through an interview and a headache diary. Of the 104 subjects reporting headaches during the last 6 months, 29 had migraine (14.2%). The prevalence of migraine was not influenced by whether the visual impairment was complete or partial. Mean frequency of migraine attacks was 2.7/month. Most subjects (96%) reported severe and/or moderate attacks. Nausea, vomiting, aggravation by activity and phonophobia were reported by 62%, 37.9%, 86.2% and 96.6% of the subjects, respectively. Visual impairment does not seem to influence prevalence of migraine or its clinical features.

Muscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity.

Background and purpose Sniff nasal inspiratory pressure (SNIP) is a voluntary inspiratory maneuver measured through a plug occluding one nostril. The investigation of the number of maneuvers necessary to reach the highest peak of SNIP in pediatric populations has been inconsistent. Thus, this study aimed to assess the reliability of SNIP in healthy children aged 6 to 11 years according to sex and age group, and to determine the optimal number of SNIP maneuvers for this age group. Methods This cross-sectional study included healthy children with normal pulmonary function. We performed 12 to 20 SNIP maneuvers, with a 30 s rest between each maneuver. The reliability was tested using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimal detectable change (MDC), and Bland-Altman analysis for agreement. Results A total of 121 healthy children (62 girls [51%]) were included in this study. The ICC and corresponding confidence interval (CI) between the highest measure and the first reproducible maneuver were 0.752 (0.656–0.824), SEM = 10.37 cmH2O, and MDC = 28.74 cmH2O. For children aged 6 to 7 years, the ICC was 0.669 (0.427–0.822), SEM = 10.76 cmH2O and MDC = 29.82 cmH2O; for children aged 8 to 11 years, the ICC was 0.774 (0.662–0.852), SEM = 9.74 cmH2O, and MDC = 26.05 cmH2O. For girls, the ICC was 0.817 (0.706–0.889), SEM = 9.40 cmH2O and MDC = 26.05 cmH2O; for boys, the ICC was 0.671 (0.487–0.798), SEM = 11.51 cmH2O, and MDC = 31.90 cmH2O. Approximately 80% of the total sample reached the highest SNIP before the 10th maneuver. Conclusions SNIP demonstrated moderate reliability between the maneuvers in children aged 6 to 11 years; older children and girls reached the SNIP peak faster. Finally, results indicated that 12 maneuvers were sufficient for healthy children aged 6 to 11 years to achieve the highest SNIP peak.