Magnetoencephalography to investigate central perception of exercise-induced breathlessness in people with chronic lung disease: A feasibility pilot
Objectives: Neuroimaging in chronic breathlessness is challenging. The study objective was to test the feasibility of magnetoencephalography (MEG) for functional neuroimaging of people with chronic breathlessness. Design: Feasibility pilot study. Setting: Respiratory clinic out-patients. Participants: 8 patients (mean age=62; (range 47-83); 4 men) with chronic non-malignant lung disease; modified MRC breathlessness score ≥3 (median mMRC=4), intensity of exercise-induced breathlessness >3/10; no contraindication to MRI scanning. Methods and measures: 4 MEG scans were conducted for each participant: (1) at rest (5 mins), (2) postseated leg exercise-induced breathlessness during recovery (10 mins). Recovery scans (2) were conducted with/without facial airflow in random order; both scans were repeated 1 h later. Participants rated breathlessness intensity (0-10 Numerical Rating Scale (NRS)) at baseline, maximal exertion and every minute during recovery, and rated acceptability of study procedures at the end of the study (0-10 NRS). A structural MRI scan was conducted for MEG coregistration and source-space analyses. Rest data were compared with data from healthy volunteers (N=6; 5 men; mean age=30.7 years±3.9 years). Results: Exercises and MEG scanning were acceptable to all participants; 7/8 completed the MRI scans. Maximum breathlessness intensity was induced by 5 min' exercise. The same level was induced for repeat scans (median=8; IQR=7-8). All recovered to baseline by 10 min. Time-frequency profiles of data from the first and last 3 min were analysed in MEG source space based on breathlessness location estimates. Source localisation was performed, but anatomical source inference was limited to the level of the lobe. Differences in areas of activity were seen: during recovery scans; with and without airflow; and between participants/normal volunteers at rest. Conclusions: MEG is a feasible method to investigate exercise-induced breathlessness in people breathless with chronic lung disease, and able to identify neural activity related to changes in breathlessness.
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