EMG-EEG Signal Coherence Impaired in Cancer-Related Fatigue (CRF) (715)

Abstract

1.Recognize that there is a coordination of electromyographic (EMG) signals with electroencephalographic (EEG) signals that govern muscle activation and endurance.2.Recognize that the coupling of EEG/EMG signals is weakened in cancer-related fatigue. Background. Recently, we reported that neuromuscular junction (NMJ) propagation is impaired in cancer-related fatigue (CRF) (Yavuzsen et al., J Pain Symptom Manag, 38:587–96, 2009). Central fatigue as defined as mechanisms arising proximal to the NMJ reduce signal coherence between electroencephalographic (EEG) and electromyographic (EMG) signals and reduce muscle (peripheral) fatigue in cancer patients. Research objectives. Based on this, we hypothesized that signals from the central nervous system (proximal to NMJ) would undergo transmission difficulties distal to NMJ. This would lead to reduced functional corticomuscular coupling during voluntary muscle contraction. Methods. Fourteen patients with advanced solid cancer and significant CRF, as well as 14 age- and gender-matched healthy controls performed a sustained isometric elbow flexion contraction of the right arm at 30% maximal level (S30) until self-perceived exhaustion. High-density (128 channels) scalp EEG data and EMG signals of the elbow flexor and extensor muscles were recorded during the S30. Coherence between the EEG and EMG signals was determined during the first half (non-fatigue) and second half (fatigue) of the S30. Results. CRF patients exhibited lower EEG-EMG coherence (P < 0.05) at beta frequency band (15-35 Hz) during the S30. Coherence did not decrease as much in CRF as in controls under the condition of muscle fatigue. Conclusion. CRF was associated with weakened functional coupling between the brain and muscle activities in a sustained submaximal motor activity. Because muscle fatigue was less significant in CRF, which normally provides afferent feedback to coupling, fatigue in cancer influenced EEG-EMG coherence less than normal controls. Impairment in NMJ propagation function in CRF contributes to diminished corticomuscular signal coupling during voluntary motor activities. Implications for research, policy, or practice. EMG-EEG coherence is impaired in CRF. Interventions to improve coherence are likely to reduce fatigue.