BACKGROUND: It is very important to find out the focal sites for the early diagnosis of multiple sclerosis, especially the discovery of tiny or potential focal site, so that multiple sclerosis can be diagnosed at the early period (the first attack) or when the focus has not displayed completely, and the evoked potential can discover the abnormality of the pathway between spinal cord to cerebral cortex. OBJECTIVE: To observe the values of motor evoked potential (MEP), somatosensory evoked potential (SEP) and evoked-related potential (P300) in the diagnosis of multiple sclerosis. DESIGN: A case-controlled study. SETTING: Neuroelectrophysiological Center of Guizhou Provincial People’s Hospital. PARTICIPANTS: Twenty-five outpatients or inpatients with multiple sclerosis were selected from the Department of Neurology, Guizhou Provincial People’s Hospital from October 2001 to March 2005. The patients were diagnosed according to the diagnostic standards of multiple sclerosis suggested by Poser et al in 1983 and MRI examination. There were 17 males and 8 females, aged 18-65 years old with an average of 39 years, and their disease courses ranged from 6 months to 5 years. Meanwhile, 30 healthy physical examinees were selected in our hospital as the control group, and they all had no abnormality by detailed inquisition, physical examination and examination of nervous system, including 15 males and 5 females, aged 20-66 years old. All the enrolled subjects were informed and agreed with the detections. METHODS: ① The MEP, SEP and P300 were detected with synergy evoked potential equipment (Oxford Instruments, UK) in all the 25 patients with multiple sclerosis and 20 healthy subjects. ② Standards for judging the abnormalities of evoked potentials: The abnormalities referred to deletion of wave form or the latency was prolonged by more than the reference value of normal subject±3SD. ③ The differences of measurement data were compared with the t test. MAIN OUTCOME MEASURES: The results of MEP, SEP and P300 in the 25 patients with multiple sclerosis and 20 healthy subjects were observed. RESULTS: All the 25 patients with multiple sclerosis and 20 healthy physical examinees were involved in the analysis of results. ① MEP results: The MEP was abnormal in 18 (72%) of the 25 patients with multiple sclerosis, manifested by the prolonged latency of cortical potential, decreased wave amplitude and prolonged CMCT, and there were significant differences as compared with those in the control group (t =2.77, 2.62, 2.67, P < 0.01). ② SEP results: The SEP was abnormal in 14 (56%) of the 25 patients with multiple sclerosis, manifested by the prolonged latencies of N13 and N20, prolonged wave intervals of N9-N13 and N13-N20, and there were significant differences as compared with those in the control group (t =2.46, 2.73, 2.56, 2.59, P < 0.01). ③ P300 results: P300 was abnormal in 13 (52%) of the 25 patients with multiple sclerosis, manifested by the prolonged latencies and decreased wave amplitudes, and there were significant differences as compared with those in the control group (t =2.44-2.72, P < 0.01). ④ Results of the combined application of MEP, SEP and P300: Abnormalities were observed in 23 (92%) of the 25 patients with multiple sclerosis. CONCLUSION: MEP, SEP and P300 detections suggested the disorders in the pathway of motor conduction, pathway of sensory conduction and cognitive function respectively. The combined application of them can improve the positive rate in diagnosing multiple sclerosis. BACKGROUND: It is very important to find out the focal sites for the early diagnosis of multiple sclerosis, especially the discovery of tiny or potential focal site, so that multiple sclerosis can be diagnosed at the early period (the first attack) or when the focus has not displayed completely, and the evoked potential can discover the abnormality of the pathway between spinal cord to cerebral cortex. OBJECTIVE: To observe the values ​​of motor evoked potential (MEP), somatosensory evoked potential (SEP) and evoked-related potential SETTING: Neuroelectrophysiology Center of Guizhou Provincial People’s Hospital. PARTICIPANTS: Twenty-five outpatients or inpatients with multiple sclerosis were selected from the Department of Neurology, Guizhou Provincial People’s Hospital from October 2001 to March 2005. The patients were diagnosed according to the diagnostic standards of multiple sclerosis suggested by Pose r et al in 1983 and MRI examination. There were 17 males and 8 females, aged 18-65 years old with an average of 39 years, and their illness courses ranged from 6 months to 5 years. Meanwhile, 30 healthy physical examinees were selected in our hospital as the control group, and all all had no abnormality by detailed inquisition, physical examination and examination of nervous system, including 15 males and 5 females, aged 20-66 years old. All the enrolled subjects were informed and agreed with the METHODS: ① The MEP, SEP and P300 were detected with synergy evoked potential equipment (Oxford Instruments, UK) in all the 25 patients with multiple sclerosis and 20 healthy subjects. ② Standards for judging the abnormalities of evoked potentials: The abnormalities referred to to deletion of wave form or the latency was prolonged by more than the reference value of normal subject ± 3SD. ③ The differences of measurement data were compared with the t test. MAIN OUTCOME MEASURES: T he results of MEP, SEP and P300 in the 25 patients with multiple sclerosis and 20 healthy subjects were observed. RESULTS: All the 25 patients with multiple sclerosis and 20 healthy physical examinees were involved in the analysis of results. ① MEP results: The MEP was abnormal in 18 (72%) of the 25 patients with multiple sclerosis, manifested by the prolonged latency of cortical potential, decreased wave amplitude and prolonged CMCT, and there were significant differences as compared with those in the control group (t = 2.77, 2.62 , 2.67, P <0.01). ② SEP results: The SEP was abnormal in 14 (56%) of the 25 patients with multiple sclerosis, manifested by the prolonged latencies of N13 and N20, prolonged wave intervals of N9-N13 and N13- N20, and there were significant differences as compared with those in the control group (t = 2.46, 2.73, 2.56, 2.59, P <0.01) .③P300 results: P300 was abnormal in 13 sclerosis, manifested by the prolonged latencies an d decreased wave amplitudes, and there were significant differences as compared with those in the control group (t = 2.44-2.72, P <0.01). ④ Results of the combined application of MEP, SEP and P300: Abnormalities were observed in 23 (92 %) of the 25 patients with multiple sclerosis. CONCLUSION: MEP, SEP and P300 detections suggested the disorders in the pathway of motor conduction, pathway of sensory conduction and cognitive function respectively respectively. The combined application of them can improve the positive rate in diagnosed multiple sclerosis.