Table 2.

Results of DSSEP findings in neutral and dynamic positions^†

	Neutral		Extension		Flexion
	N13	N20	N13	N20	N13	N20
Latency (ms)	13.2 ± 1.1	18.88 ± 1.09	13.25 ± 1.01	19.06 ± 1.01	13.14 ± 1.07	18.95 ± 1.07
p_value ‡			0.15	0.09	0.43	0.3
Amplitude (uV)	2.66 ± 1.42	2.7 ± 1.59	2.17 ± 1.29	2.53 ± 1.3	2.18 ± 1.59	2.56 ± 1.54
p_value ‡			0.000017 ***	0.29	0.0026 **	0.25
Amplitude Ratio §			0.72 ± 0.34	0.97 ± 0.29	0.73 ± 0.43	0.97 ± 0.29
Absent waves(Left, Right) ¶	4 (4,4)	0	8 (7,6)	2 (1,2)	10 (7,9)	1 (1,1)

** p_value< 0.01; *** p_value< 0.001

^† For absent N13 or N20 waves, their latencies were excluded and amplitudes were set as the baseline value (0 mV) for statistical analysis

^‡ The p_values were calculated with the student’s t-test by comparing the DSSEP value at dynamic (extension or flexion) position with neutral position

^§ Each patients’ amplitude ratios were calculated with the following method: Amplitude Ratio = amplitude at dynamic (extension or flexion) position ÷ amplitude at neutral position

^¶ The number of patients whose waves at either left or right side at specific position was lost. The number of absent waves at left and right sides are respectively listed in the bracket