Fig. 1.

Pattern categories according to the presence of N20 or P25 on cortical somatosensory evoked potential recordings. Type I (n = 91): 51 cases of CPC 1–2 and 40 cases of CPC 3–5; type II (n = 58): all CPC 3–5; type III (n = 2): all CPC 4–5; and type IV (n = 41): all CPC 4–5. Erb, Erb’s point; FZ, frontal pole electrode; CII, C2 spinous process; C3’ and C4’, contralateral somatosensory cortexes; CPC, Cerebral Performance Category