Objective: To investigate cortical brain activity changes during complex gait in Parkinson’s disease (PD) patients with and without freezing of gait (FOG) using functional near infrared spectroscopy (fNIRS).

Background: Complex gait tasks, such as navigating narrow spaces and turns, are particularly challenging for freezers, often triggering freezing episodes. So far, the neural resource limitations underlying these gait difficulties are largely unknown.

Method: Eleven PD freezers and non-freezers on medication, and 15 age-matched controls performed 3 blocks (4x6m walks or 8 turns per block) each of straight walking, slalom, and 360 degrees turning in place, interspersed with 15 seconds of standing rest. Changes in oxy- (HbO) and deoxygenated haemoglobin (HbR) concentrations from posterior parietal to prefrontal regions was captured with a 32-optode mobile fNIRS device. Gait-related activation was estimated in the first-level general linear model, and two contrasts (slalom vs walking and turning vs walking) were compared between the three groups using non-parametric Kruskal-Wallis χ² tests.

Results: Controls showed larger increases in HbO and decreases in HbR concentrations during slalom vs walking, compared to both freezers and non-freezers in the left prefrontal regions corresponding to Brodmann areas (BA) 8 and 9 (BA8 – HbO & HbR: χ² = 10.9, p = 0.004, BA9 – HbR: χ² = 6.6, p = 0.035). Differences in slalom vs walking were also found between PD groups, with freezers showing smaller increases in HbO concentrations in the left posterior parietal cortex (BA 7) compared to non-freezers (BA7 – HbO: χ² = 7.2, p = 0.026). Finally, for turning vs walking, freezers showed smaller decreases in HbR concentrations in the right primary sensorimotor cortices (BA 2 and 4), compared to non-freezers (BA2 – HbR: χ² = 7.0, p = 0.030, BA4: χ² = 7.2, p = 0.027).

Conclusion: These preliminary results show that PD participants were less able to recruit prefrontal goal-directed motor control resources during vision-guided complex gait (slalom) compared to controls. On the other hand, freezers showed reduced recruitment of visuomotor integration resources during vision-guided complex gait, and reduced recruitment of primary sensorimotor resources during proprioception-guided complex gait (alternating turning in place), suggesting multiple contributors to gait breakdown.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reduced-parietal-and-sensorimotor-cortex-recruitment-during-complex-gait-in-parkinsons-disease-patients-with-freezing-of-gait/