Postural instability in HIV infection: relation to central and peripheral nervous system markers

Abstract

Objectives: Determine the independent contributions of central nervous system (CNS) and peripheral nervous system (PNS) metrics to balance instability in people with HIV (PWH) compared with people without HIV (PWoH).Methods: Volumetric MRI (CNS) and two-point pedal discrimination (PNS) were tested as substrates of stance instability measured with balance platform posturography.Design: 125 PWH and 88 PWoH underwent balance testing and brain MRI. Results:The PWH exhibited stability deficits that were disproportionately greater with eyes closed than eyes open compared with PWoH. Further analyses revealed that greater postural imbalance measured as longer sway paths correlated with smaller cortical and cerebellar lobular brain volumes known to serve sensory integration; identified brain/ sway path relations endured after accounting for contributions from physiological and disease factors as potential moderators; and multiple regression identified PNS and CNS metrics as independent predictors of postural instability in PWH that differed with the use of visual information to stabilize balance. With eyes closed, temporal volumes and twopoint pedal discrimination were significant independent predictors of sway; with eyes open, occipital volume was an additional predictor of sway. These relations were selective to PWH and were not detected in PWoH. Conclusion:CNS and PNS factors were independent contributors to postural instability in PWH. Recognizing that myriad inputs must be detected by peripheral systems and brain networks to integrate sensory and musculoskeletal information for maintenance of postural stability, age-or disease-related degradation of either or both nervous systems may contribute to imbalance and liability for falls.

Contributions of cerebral white matter hyperintensities, age, and pedal perception to postural sway in people with HIV

“…Sensory compromise of visual acuity and touch discrimination also accompanies aging even in healthy individuals [58]. This array of age-related sensorimotor decline of the peripheral nervous system together with central nervous system degradation of white matter structural integrity can be exacerbated or even accelerated by chronic diseases, including HIV infection [43], and contribute to postural instability [41,42] and falls [34,35]. Relevant to the current study, greater instability of quiet standing was heralded by larger volumes of brain WMH, poorer sensory discrimination measured on the soles of the feet, and length of HIV infection, each of which worsens in aging with HIV and increases the risk of falls.…”

“…Given the decades of reports on the relations between WMH presence and postural instability in aging and disease including HIV infection, we tested whether this relation was also influenced by factors we previously found to contribute to WMH presence and size or to postural instability in PWH [37,41]. Accordingly, we posed the following questions: does postural instability measured as sway path length correlate with WMH volumes similarly in HIV and control groups?…”