What is the role of the cortex in essential tremor?

Conflicting results on the existence of tremor related cortical activity in essential tremor (ET) have raised questions on the role of the cortex in tremor generation. Here we attempt to address these issues. We recorded 64 channel surface EEG and EMG from forearm muscles in 15 patients with definite ET. EEG and EMG power spectra, relative power of the rhythmic EMG activity, relative EEG power at the tremor frequency and EEG-EMG and EEG-EEG coherence were calculated and their dynamics over time explored. Corticomuscular delay was studied using a new method for narrow band coherent signals. Corticomuscular cohere…