Chest wall motion during speech production in patients with advanced ankylosing spondylitis

To test the hypothesis that ankylosing spondylitis (AS) alters the pattern of chest wall motion during speech production.

The pattern of chest wall motion during speech was measured with respiratory inductive plethysmography in 6 participants with advanced AS (5 men, 1 woman, age 45+/-8 years, Schober test 1.45+/-1.5 cm, Bath Ankylosing Spondylitis Functional Index [BASFI] score 6+/-1.7) and 6 healthy volunteers, matched for age and gender. Measurements were made with participants in the upright seated and upright standing body position.

During reading in the seated and standing body positions, the rib cage wall volume displacements were smaller and abdominal wall volume displacements were larger in participants with AS than in healthy controls. There were no differences in the overall lung volume displacements recorded during the expiratory limb of reading in either body position. In the participants with AS, the rib cage remained near the end-expiratory level in both the seated and standing body position, differing from that for the control group.

In individuals with advanced AS, the abdomen is the primary contributor to volume displacement. In the absence of speech impairment in participants with AS, the data show the capacity of the abdomen to compensate for the decreased compliance of the rib cage.