Posterior Tibial Somatosensory Evoked Potentials (PTSEPs) in Thoracic Myelopathy

J Korean Neurol Assoc > Volume 10(1); 1992 > Article

Journal of the Korean Neurological Association 1992;10(1): 72-78.

이광우, 이남수

서울대학교 신경과.

Posterior Tibial Somatosensory Evoked Potentials (PTSEPs) in Thoracic Myelopathy

Kwang-Woo Lee, M.D., Nam-Soo Lee, M.D.

Department of Neurology, College of Medicine, Seoul National University

Abstract

The authors perforrned the posterior tibial somatosensory evoked potentials(PTSEP) on 37 patients who had typical symptoms and signs of thoracic myelopathy to evaluat the value of the PTSEP in diagnosing and differentiating among the thoracic lesions The result showed the abnormal PTSEP features which were suggestive of thoraci myelopathy in 33 of 37(89.2%). The most frequent abnormalities were the prolonged central conduction(59.5%), which were either the only one(40.6%) or combined with poor wave formation (18.9%). The second comrnon abnorrnal PTSEP findings were the decreased Pl amplitude relative to TNl amplitude with hanng nonnal value of TNl-P interwave latencies (29.7%). When we divided those 37 subjects into the demyelinating (N =19) and the non-demyelinating group(N=18), the prolonged TNl-Pl interwave latencies were more prominent in the demyelinating(68.4%) than in the non-demyelinating group (50.0%). In contrast, the only relative reduction of Pl amplitude with normal central conduction was more marked in the non-demyelinating(38.9%) than in the demyelinating group(21.1%). However, both of them did not show statistical significances (p <0.254, p <0.235, respectively). The PTSEP methods were found superior to spine MRI in sensitivity in the demyeli nating group, as the PTSEP revealed abnormal findings in 12 subjects with normaI spine MRI. Therefor it is concluded that the PTSEP studies would be helpful in diagnosing the thoracic lesions, especially in patients with the demyelinating lesions. However. Those pararnmters of the prolonged central conduction(TNl-P1) or the relative amplitude redu ction of cortical patentials(Pl) were not significant in differentiating the demyelinating from the non-demyelinating lesions.