Using posturography to detect unsteadiness in 13 patients with peripheral neuropathy: a pilot study.

Our aims were to use posturography to see if sway pattern differed between patients with large-fiber peripheral neuropathy and normal control subjects and, if it did, to compare posturography with conventional electromyography (EMG) as screening tools for large-fiber peripheral neuropathy. Thirteen patients who came to our neurophysiology laboratory with a preliminary diagnosis of peripheral neuropathy (made by their referring physicians) were compared with 7 nonmatched control subjects. All subjects received a neurologic examination and underwent posturography and conventional EMG. Results of posturography and conventional EMG were compared. Posturography showed abnormal sway patterns only in patients who had EMG abnormalities consistent with large-fiber peripheral neuropathy. These sway patterns differed significantly from those of the control subjects. Posturography seems to be a useful and well-tolerated screening test for patients with a history suggestive of peripheral neuropathy, and results of posturography agree with those of conventional EMG. Moreover, posturography directly measures increased sway in these patients and may be used as a more direct screen for risk of falls in this population.

Airway resistance and tissue elastance from input or transfer impedance in bronchoconstricted monkeys.

Ascaris suum (AS) challenge in nonhuman primates is used as an animal model of human asthma. The primary goal of this study was to determine whether the airways and respiratory tissues in monkeys that are bronchoconstricted by AS inhalation behave similarly to those in asthmatic humans. Airway resistance (Raw) and tissue elastance (Eti) were estimated from respiratory system input (Zin) or transfer (Ztr) impedance. Zin (0.4-20 Hz) and Ztr (2-128 Hz) were measured in anesthetized cynomolgus monkeys (n = 10) under baseline (BL) and post-AS challenge conditions. Our results indicate that AS challenge in monkeys produces 1) predominantly an increase in Raw and not tissue resistance, 2) airway wall shunting at higher AS doses, and 3) heterogeneous airway constriction resulting in a decrease of lung parenchyma effective compliance. We investigated whether the airway and tissue properties estimated from Zin and Ztr were similar and found that Raw estimated from Zin and Ztr were correlated [r(2) = 0.76], not significantly different at BL (13.6 +/- 1.4 and 13.1 +/- 0.9 cmH(2)O. l(-1). s(-1), respectively), but significantly different post-AS (20.5 +/- 4.5 cmH(2)O. l(-1). s(-1) and 18.5 +/- 5.2 cmH(2)O. l(-1). s(-1)). There was no correlation between Eti estimated from Zin and Ztr. The changes in lung mechanical properties in AS-bronchoconstricted monkeys are similar to those recently reported in human asthma, confirming that this is a reasonable model of human asthma.