Postural Instability in Parkinson’s Disease: Righting Reactions, External Perturbations and Proprioception
Postural Instability in Parkinson’s Disease: Righting Reactions, External Perturbations and Proprioception
The Impact of Parkinson’s on Postural Control
Parkinson’s disease is well known for its impact on motor function. Proprioception and postural stability are specific components often affected by Parkinson’s. Bradykinesia, rigidity and impaired proprioception reduce the effectiveness of automatic righting reactions, increasing falls risk when unexpected external perturbations occur. Cognitive changes associated with PD further influence predictive balance strategies, impacting rehab outcomes.
Righting reactions are automatic responses that help us maintain or regain upright posture and may occur at the ankles, hips, trunk and/or arms prior to a stepping reaction. In PD, these reactions are often diminished or delayed due to bradykinesia, rigidity and/or cognitive impairments.
Our SIG identified the reactive component of the MiniBEST as the most suitable tool for assessing reactive balance in this context.
When introducing training strategies, the SIG recommended:
- volitional step training as a starting point, progressing to static reactive balance training and then more dynamic reactive balance training
- different exercises and environmental set ups for these, including:
- use of the ‘clock yourself’ app
- blaze pods
- foam pads
- wheeled dollies
- treadmill training (including change of direction, trip training, emergency stop)
- the use of additional anterior perturbations, such as use of a bungee pulling forwards during a dynamic task
Proprioception and Parkinson’s Disease
Reduced dopamine in the basal ganglia alters sensorimotor integration, leading to impaired proprioception. When combined with altered cortical processing, this results in proprioceptive deficits which then contributes to reduced postural instability. This ultimately results in increased postural sway and falls and an increased dependence on vision as a compensatory mechanism.
Our review of the literature confirmed proprioceptive deficits as a key factor in postural instability in Parkinson’s. However, the evidence around proprioceptive training as a standalone intervention is limited. Research suggests integrating proprioceptive challenges into broader neuro rehab programs that include balance training, strength, mobility and treadmill-based interventions.
Assessing Proprioception and Postural Stability
Assessment should combine proprioceptive-specific measures with functional outcome measures. Options include:
- Joint Position Sense Test / Joint Position Error Test
- Distal Up/Down Test
- Force plates for postural sway
- Functional measures such as the Modified CTSIB, MiniBEST, Berg Balance Scale, and Functional Reach Test
Evidence-Based Treatment Approaches
Limited research actually shows the best way to treat proprioception. The research is inconclusive about benefits of pure proprioceptive training for functional improvements and it is recommended that proprioceptive training be incorporated with routine rehab. A combination of sensory and motor treatment modalities is recommended for treatment of balance dysfunction and postural instability.
- Amplitude-based therapy – LSVT BIG (similar in philosophy to PD Warrior): Shown to improve proprioception after an 8-week intervention, though translation to functional gains remains inconclusive (Peterka et al, 2020)
- Multi-modal neuro rehab: Proprioceptive training should be combined with balance, strength, ROM and gait training.
- Dynamic task practice: Integrating dual-tasking, environmental variation, and perturbation training leads to better real-world carryover.
Practical Clinical Tips
- Use external targets: Encourage reaching for objects to enhance proprioceptive feedback.
- Vary visual input: Incorporate eyes-closed tasks or shifting gaze away from the floor.
- Mirror feedback: Support amplitude and movement precision during exercises.
- Change body position: Incorporate multi-directional stepping and reaching.
- Vary surfaces: Use foam pads, Bosu balls or inclines to increase proprioceptive demand.
- Add dual tasks: Cognitive or manual challenges to increase complexity.
Conclusion
Postural instability in Parkinson’s disease requires a neuro rehab approach that integrates proprioceptive training, balance strategies, and external perturbation challenges. Clinical practice demonstrates that layering multiple strategies enhances safety and functional independence. We encourage therapists to share their experiences and strategies, aiming to make rehab in this area both challenging and fun.
Reflection Questions for Clinicians
- What are your go-to interventions for postural instability in Parkinson’s disease?
- What has helped to change your practice?
- How do you currently assess and progress reactive balance training in your practice?
- Which strategies have your clients reported as most effective for falls prevention?
Responses