[Correlation between abnormal SSEP and clinicoradiological findings in cervical lesions]

The purpose of this paper is to evaluate the short latency somatosensory evoked potentials (SSEP) in the diagnosis of cervical lesions. Recordings were obtained from 59 patients with cervical lesions which included 24 cases of cervical spondylosis, 4 cases of disc herniation, 14 cases of OPLL, 4 cases of intramedullary tumor, 7 cases of extramedullary tumor and 6 cases of syringomyelia. SSEP changes in these cases were classified into three major types as follows: type I; normal SSEP, type II; prolongation of interpeak latency, and type III; absence of the component of SSEP. Types II and III were subdivided into two subgroups, respectively, as follows: type IIa; prolongation of interpeak latency between P9 and P11, type IIb; prolongation of P11-P13, type IIIa; no responses after P11 and type IIIb; no responses after P13. Type I was detected in 25 cases (42%), type II in 16 cases (27%), and type III in 18 cases (31%). These SSEP findings were compared with clinicoradiological findings. In type I, the locations of the lesions confirmed by the radiological findings were variable, and there was no definite tendency in the localizations. 80% of type I showed only numbness of extremities or disturbance of the superficial sensations. The cervical lesion was located just under the C5 vertebral level in type IIa and IIIa, while the lesion was extended above the C4 vertebral level in type IIb and IIIb. These results were explained by the generation sites of P11 and P13 (P11 originated from the lower dorsal column, and P13 from nearby the dorsal column nucleus).(ABSTRACT TRUNCATED AT 250 WORDS)