Normal controls HAM patients   Amplitude (μV) Mean SD Mean SD P-value N20o-p 2.4 1.1 2.7 1.1 0.82 N20p-P25p 5.0 2.6 7.0 3.2 0.50 P25p-N33p 3.6 2.5 4.0 2.5 0.55 Early HFOs 0.27 0.23 0.22 0.14 0.56 Late HFOs 0.26 0.15 0.28 0.09 0.82

Table 1: Amplitudes of raw SEPs and HFOs; Comparisons were performed with unpaired t-test analysis.