Magnetic resonance imaging of muscle in amyotrophic lateral sclerosis

In the present study we were interested to determine whether the maximum unilateral nasal airflow associated with the nasal cycle (Fmax physiol) was equivalent to the maximum unilateral nasal airflow that could be achieved by the application of a topical nasal decongestant (Fmax pharmacol). Eight healthy subjects (three male and five female, aged between 19-28 years) were recruited for this study. Unilateral nasal airflow was measured using posterior rhinomanometry at the inspiratory reference pressure of 75 Pa by alternately occluding each nostril with surgical tape. The study was run over 2 consecutive days. On day one, measurements of unilateral nasal airflow were performed every hour for 8 h in each subject and Fmax physiol was found to be 265 cm3/sec (147) (median and interquartile range). On day 2 the median unilateral nasal airflow before application of the nasal decongestant was 171 cm3/sec (140) and this increased to 251 cm3/sec (127) (p = 0.046) at 15 min and to 278 cm3/sec (134) (p = 0.005) at 45 min after application of the decongestant (Fmax pharmacol). A paired comparison of Fmax physiol and Fmax pharmacol showed that these nasal airflow measurements were not significantly different (p > 0.999). The results show that there was no difference between the maximum physiological decongestion produced during the course of the nasal cycle and that produced pharmacologically by a topical nasal decongestant. This indicates that the point of maximal sympathetic vasoconstrictor tone occurring during the nasal cycle causes a constriction of the nasal venous sinuses that is equal to the constrictor response that can be achieved by applying a topical sympathomimetic medication.