Time-frequency analysis of tremors

P. O'Suilleabhain
1998 Brain  
Time-frequency analysis methods were applied to surface EMG records of patients with tremor. Variation in tremor frequency over time and between muscles was measured in subjects with Parkinson's disease (n ⍧ 20), essential tremor (n ⍧ 8) and psychogenic tremor (n ⍧ 7). The effect of externally paced voluntary contractions on tremor frequency was also characterized. Psychogenic tremor involved fewer limbs and fewer limb segments than Parkinson's disease rest tremor and essential tremor, and its
more » ... al tremor, and its frequency was less consistent. In all subject groups, muscles within a single extremity generally had identical instantaneous frequencies. Frequency dissociation, used here to describe a modal contemporaneous frequency difference of more than 0.1 Hz between two extremities, was demonstrated for symptomatic tremors in 17 subjects with Parkinson's disease, in four subjects with essential tremor and in none of the subjects with psychogenic tremor. Dissociation between tapping and tremor limbs was demonstrated in an additional two subjects with Parkinson's disease and in all four remaining essential tremor subjects but in none of the psychogenic tremor subjects. Tremor maintained a different frequency from the tapping limb in Parkinson's disease and essential
doi:10.1093/brain/121.11.2127 pmid:9827772 fatcat:vkvcsefbmreg3kkmllabtrszw4