Unraveling the mechanisms underlying postural instability in Parkinson’s disease using dynamic posturography

Abstract

Postural instability, one of the cardinal symptoms of Parkinson’s disease (PD), has devastating consequences for affected patients. Better strategies to prevent falls are needed, but this calls for an improved understanding of the complex mechanisms underlying postural instability. We must also improve our ability to timely identify patients at risk of falling. Dynamic posturography is a promising avenue to achieve these goals. The latest moveable platforms can deliver ‘real-life’ balance perturbations, permitting study of everyday fall circumstances. Dynamic posturography studies have shown that PD patients have fundamental problems in scaling their postural responses in accordance with the need of the actual balance task at hand. On-going studies evaluate the predictive ability of impaired posturography performance for daily life falls. We also review recent work aimed at exploring balance correcting steps in PD, and the presumed interaction between startle pathways and postural responses.

Keywords::

• dynamic
• Parkinson’s disease
• postural control
• posturography falls
• startle

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Postural instability is a frequent and debilitating, yet poorly understood symptom of Parkinson’s disease (PD).

• • PD patients have a fundamental problem in scaling their postural responses, partly due to abnormal proprioceptive-motor integration.

• • Dynamic posturography is a potential tool to unravel the mechanisms underlying postural instability in PD.

• • Recent innovations in posturography allow for delivering ‘real-life’ balance perturbations, permitting study of everyday fall circumstances.

• • Dynamic posturography cannot yet be clinically applied to identify PD patients prone to falling, but more work remains needed in this area.

• • Future research in patients with PD should study the balance correcting steps at the limits of stability and the possible interaction between startles and postural responses.