Vestibular and Proprioceptive Alteration Influence Postural Instability During Dual Tasks in Adults Diagnosed with HIV [Texas Woman's University]
Background & Purpose: People diagnosed with HIV can exhibit impaired postural control as a consequence of infection or from secondary effects of medication. Therefore, the purpose of this study is to assess postural control during four single and four dual tasks to evaluate the role of the vestibular and proprioceptive system during these balance activities. We hypothesize that postural stability will decrease with the increase of task complexity. Number of Subjects : 24 Materials/Methods : The study was conducted in San Juan, Puerto Rico at La Perla de Gran Precio Rehabilitation Clinic for HIV. 24 subjects (13 male and 11 female) participated in the study. Age range was 59.2± 1.7 years old. Participants had to be diagnosed with HIV and have a CD4 count >200 cells/uL to enroll in the study. After signing the informed consent and collecting demographic data, a member of the research team placed a lumbar accelerometer on each subject. Each participant was instructed to stand in a static bi-pedal posture on a firm surface or a thick foam pad . Each task took 15 seconds to be performed, multiply per nine balance tasks (18x15=3 minutes and 10 seconds), plus the 2 minutes of rest between every two tasks (2x6 minutes=12). The eight remaining balance tasks will be performed with a thick balance foam mat and further divided into two parts, four single and four dual cognitive tasks (subjects counting backward 3 numbers at a time). Results : Postural control was measured with Body-worn accelerometers (ACC). The two variables of interest in this study were jerk sway acceleration in an anterior-posterior (A-P) and mediolateral direction (M-L), m^2/s^5. A MANOVA analysis was used to evaluate Jerk of sway acceleration in both directions, between baseline (BL) (firm surface eyes open) and single/double tasks. Postural control was significantly altered during single (ACC BL 0.020 ± .01 m^2/s^5 versus ACC single task 0.20 ± 0.02 m^2/s^5 P< 0.005) and dual tasks (ACC BL 0.020 ± .01 m^2/s^5 versus ACC dual task 0.23 ± 0.03 m^2/s^5 P< 0.005) when visual input was canceled, and vestibular system was altered in an A-P direction. Thus ACC sway acceleration was increased in an anterior-posterior direction when the Ve and Pro system was challenged at the same time during the Vi system where canceled. Conclusions : Single and dual tasks showed similar challenge and results regarding increased acceleration and instability. It appears that the vestibular and proprioceptive systems could be impaired in HIV diagnosed people. Because there is no fall history among the participants of this study and these findings, it seems that patients with HIV rely on the visual system to a higher degree to attain postural control. Clinical Relevance : Identify balance disturbance in early stages to reduce the risk of fall.
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