Sarasso E1,2, Piramide N1, Chiesi M1, Volontè MA3, Fichera M3, Galantucci S3, Gatti R4, Tettamanti A2, Agosta F1, Filippi M5
1San Raffaele Scientific Institute, Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Milano, Italy, 2San Raffaele Scientific Institute, Laboratory of Movement Analysis, Milano, Italy, 3San Raffaele Scientific Institute, Department of Neurology, Institute of Experimental Neurology, Division of Neuroscience, Milano, Italy, 4Hunimed University, Physiotherapy Degree Course, Rozzano, Milano, Italy, 5San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Milano, Italy

Background: Dual-task is one of the most challenging situation for PD patients and usually impacts on postural stability and gait safety.

Purpose: The aims of this study were to assess:
i) the brain functional reorganization and
ii) gait changes performing dual-task following 6 weeks of action observation training (AOT) and motor imagery (MI) associated with gait/balance exercises in PD patients with postural instability and gait disorders (PD-PIGD).

Methods: Twenty PD-PIGD subjects were randomized into 2 groups: the AOT-MI group performed a 6-week training (1-hour session 3 times a week) consisting of AOT-MI combined with practicing the observed-imagined gait and balance exercises; LANDSCAPE-group performed the same exercises combined with watching landscape videos. Exercises were increasingly difficult up to include dual-task during complex gait and balance tasks.
At baseline (T0) and week 6 (W6), patients underwent:
i) functional MRI (fMRI) assessment, including a dual-task condition (foot anti-phase movements while counting backwards by threes starting from 100) and
ii) gait/balance evaluations including Timed Up and Go test (TUG) and TUG associated with motor (TUG-MOT) and cognitive dual-tasks (TUG-COG), MiniBESTest and Activities Balance Confidence questionnaire (ABC).

Results: At W6, compared to T0, both groups showed an improvement in TUG execution time, whereas only the AOT-MI group improved in TUG-COG, TUG-MOT, MiniBESTest and ABC. AOT-MI also showed improvements in ABC and MiniBESTest relative to LANDSCAPE. At W6 relative to T0, during the fMRI dual-task condition, the AOT-MI group showed a reduced recruitment of frontal, occipital, insular areas and hippocampus and an increased activity of parietal areas. The LANDSCAPE group presented a decreased activity of occipital areas and an increased recruitment of fronto-temporal areas. AOT-MI relative to LANDSCAPE group showed reduced recruitment of frontal, occipital, and temporal areas and of the right putamen.

Conclusion(s): Our results suggest that increasingly difficult exercises (up to include dual-task during complex gait and balance tasks) improve gait speed in PD patients; however, only when exercises was preceded by a motor-learning facilitation approach (AOT-MI), PD patients showed gait/balance improvements and increased brain efficiency during dual-task circumstances, which are among the most challenging for PD-PIGD patients.

Implications: A combined cognitive-motor rehabilitation approach is more effective than a pure motor training to improve gait/balance performance and to modulate brain activity during dual-task in patients with PD-PIGD.

Keywords: Parkinson's disease, action observation and motor imagery, fMRI dual-task

Funding acknowledgements: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Topic: Neurology; Disability & rehabilitation

Ethics approval required: Yes
Institution: San Raffaele Scientific Institute
Ethics committee: Human Research Ethics Committee
Ethics number: 44-int-2017 AOT-MI in PD-PIGD

All authors, affiliations and abstracts have been published as submitted.

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