Measuring prefrontal cortical activity during dual task walking in patients with Parkinson's disease: feasibility of using a new portable fNIRS device.

Freek Nieuwhof,Miriam F Reelick,Inbal Maidan,Jeffrey M Hausdorff,Makii Muthalib,Anat Mirelman,Marcel G M Olde Rikkert,Bastiaan R Bloem,Jurgen A H R Claassen

doi:10.1186/s40814-016-0099-2

Abstract

BackgroundMany patients with Parkinson’s disease (PD) have difficulties in performing a second task during walking (i.e., dual task walking). Functional near-infrared spectroscopy (fNIRS) is a promising approach to study the presumed contribution of dysfunction within the prefrontal cortex (PFC) to such difficulties. In this pilot study, we examined the feasibility of using a new portable and wireless fNIRS device to measure PFC activity during different dual task walking protocols in PD. Specifically, we tested whether PD patients were able to perform the protocol and whether we were able to measure the typical fNIRS signal of neuronal activity.MethodsWe included 14 PD patients (age 71.2 ± 5.4 years, Hoehn and Yahr stage II/III). The protocol consisted of five repetitions of three conditions: walking while (i) counting forwards, (ii) serially subtracting, and (iii) reciting digit spans. Ability to complete this protocol, perceived exertion, burden of the fNIRS devices, and concentrations of oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin from the left and right PFC were measured.ResultsTwo participants were unable to complete the protocol due to fatigue and mobility safety concerns. The remaining 12 participants experienced no burden from the two fNIRS devices and completed the protocol with ease. Bilateral PFC O2Hb concentrations increased during walking while serially subtracting (left PFC 0.46 μmol/L, 95 % confidence interval (CI) 0.12–0.81, right PFC 0.49 μmol/L, 95 % CI 0.14–0.84) and reciting digit spans (left PFC 0.36 μmol/L, 95 % CI 0.03–0.70, right PFC 0.44 μmol/L, 95 % CI 0.09–0.78) when compared to rest. HHb concentrations did not differ between the walking tasks and rest.ConclusionsThese findings suggest that a new wireless fNIRS device is a feasible measure of PFC activity in PD during dual task walking. Future studies should reduce the level of noise and inter-individual variability to enable measuring differences in PFC activity between different dual walking conditions and across health states.Electronic supplementary materialThe online version of this article (doi:10.1186/s40814-016-0099-2) contains supplementary material, which is available to authorized users.

Highlights

Many patients with Parkinson’s disease (PD) have difficulties in performing a second task during walking
During walking while reciting digit spans, participants recited an average of 6.0 spans, with a mean success rate of 88.4 %. In this pilot study, we aimed to examine the feasibility of measuring prefrontal cortex (PFC) activity during dual task walking in patients with PD with use of a portable Functional near-infrared spectroscopy (fNIRS) device
Good feasibility of the portable fNIRS device was demonstrated by the fact that most participants experienced a low burden of the two fNIRS devices placed on the forehead during walking, were able to perform the different dual task walking paradigms, and reported that it took them little effort to complete the full protocol

Summary

Introduction

Many patients with Parkinson’s disease (PD) have difficulties in performing a second task during walking (i.e., dual task walking). Functional near-infrared spectroscopy (fNIRS) is a promising approach to study the presumed contribution of dysfunction within the prefrontal cortex (PFC) to such difficulties. In this pilot study, we examined the feasibility of using a new portable and wireless fNIRS device to measure PFC activity during different dual task walking protocols in PD. As a consequence of performing two tasks at the same time, gait and/or their performance on the secondary task at hand deteriorates [2,3,4] These difficulties in dual task walking often lead to increased disability, increased fall risk, and reduced quality of life [1, 5, 6]. Altered functioning of the PFC during dual task walking in PD might explain their difficulties and should be further examined

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