Complexity

Research Article

New Perspectives for Computer-Aided Discrimination of Parkinson’s Disease and Essential Tremor

Table 1

Most discriminative tremor metrics, extracted from hdEMG recordings. The best cut-off value was selected as closest to upper left corner in the ROC curve. Normalization of values in postural condition to the ones in rest condition increased discriminative power of metrics. For informative reasons, the tremor amplitude and tremor frequency as assessed from the neural drive are also listed, though none of them adequately discriminated the ET and PD patients.


Symbol	Metric	Task	Hand	Cut-off	Sensitivity (%)	Specificity (%)	AUC (95% CI)	PPV (%)	NPV (%)	value	value

N1	Tremor amplitude in neural drive	AO	ND	0.630	59.3	51.9	0.54 (0.38, 0.70)	55.2	56.0	337.0	0.634
N1	Tremor amplitude in neural drive	WE	D	0.584	63.0	77.8	0.69 (0.54, 0.83)	73.9	67.7	228.0	0.018

N2	Tremor frequency in neural drive	AO	ND	6.248	40.7	63.0	0.41 (0.26, 0.57)	52.4	51.5	301.0	0.270
N2	Tremor frequency in neural drive	WE	D	5.749	63.0	51.9	0.53 (0.37, 0.69)	56.7	58.3	345.0	0.734

N3	Dominant hand tremor symmetry	AO	ND	0.059	74.1	63.0	0.73 (0.59, 0.86)	66.7	70.8	199.0	0.004
N3	Dominant hand tremor symmetry	WE	D	0.079	85.2	74.1	0.79 (0.65, 0.92)	76.7	83.3	156.5	<0.001

N3	Normalized dominant tremor hand symmetry	AO	D	1.446	85.2	74.1	0.89 (0.80, 0.98)	76.6	83.3	81.0	<0.001

N4, N5	Mean interlimb tremor symmetry in extensors and flexors	AO	both	0.035	77.8	77.8	0.75 (0.61, 0.89)	77.8	77.8	185.0	0.002
N4, N5	Mean interlimb tremor symmetry in extensors and flexors	WE	both	0.033	81.5	59.3	0.71 (0.56, 0.85)	66.7	76.2	213.5	0.009

N7	Normalized global tremor symmetry	AO	both	1.555	85.2	96.2	0.94 (0.86, 1.00)	95.8	86.7	45.0	<0.001
N7	Normalized global tremor symmetry	WE	both	1.672	85.2	100	0.90 (0.79, 1.00)	100	87.1	76.5	<0.001

N9	Normalized coefficient of variability for motor unit synchronization	AO	both	0.244	74.1	74.1	0.76 (0.63, 0.90)	74.1	74.1	172.0	0.001
N9		WE	both	0.253	55.6	81.5	0.67 (0.52, 0.82)	75.0	64.7	240.0	0.031

ET patients: positive samples; PD patients: negative samples; normalized to RE task; mean value of metrics N4 and N5; metric N7 represents N6, normalized to RE task; metric N9 represents N8, normalized to RE task; D: dominant tremor hand; ND: nondominant tremor hand.