Effect of acupuncture on pattern visual evoked potential of cerebral visual impairment in children aged 3-10 years / 中国针灸

OBJECTIVE@#To observe clinical effect of acupuncture combined with conventional visual stimulation on cerebral visual impairment (CVI) in children aged 3-10 years and influence on the pattern visual evoked potential (P-VEP).@*METHODS@#A total of 60 cases of children aged 3-10 years with CVI were randomly divided into an observation group and a control group, 30 cases in each group. The children in the control group received conventional visual stimulation therapy, 1 month as a course of treatment. On the basis of the control group, the children in the observation group was treated with acupuncture at Baihui (GV 20), Jingming (BL 1), Taiyang (EX-HN 5), Sibai (ST 2), etc. 3 times a week, and the treatment was given 4 weeks continuously as a course. Both groups received 3 courses of treatment. The visual acuity and P-VEP improvement were compared between the two groups before and after treatment.@*RESULTS@#After treatment, the incubation period (P100-L) of the two groups was shorter than before treatment, and the amplitude (P100-A) was higher than before treatment (@*CONCLUSION@#Acupuncture combined with conventional visual stimulation can improve the incubation period (P100-L) and amplitude (P100-A) of P-VEP in children with CVI, and improve the best corrected visual acuity in children, the clinical effect is better than the conventional visual stimulation alone.

Atypical Presentation of Medullary Syndrome in a Young Woman

Wallenburg syndrome occurs due to damage to lateral segment of the medulla. Medial medullarysyndrome occurs due to damage to upper portion of the medulla. I report a case of a 30 years old woman diagnosed with medullary syndrome[both medial & lateral features] in absence of CT scan findings sent to the department of Physiology for electrophysiological tests like nerve conduction studies, blink reflex, brainstem auditory evoked potential (BERA) & visual evoked potential (VEP). She had loss of sensations on the ipsilateral half of face (right), hemisensory loss on contralateral trunk & extremities, headache, contralateral hemiparesis (left), ipsilateral lingual paresis with atrophy, fibrillations with contralateral positive Babinski’s sign. The electrophysiological tests showed decrease in conduction velocity of right facial nerve, left tibial & peroneal nerves with decreased amplitude. The nerve conduction studies of median nerve (both motor & sensory) were normal. In blink reflex, latency of R2 ipsilateral & R2 contralateral of supraorbital nerves were increased on right side. There were increasedlatencies of waves II, III, IV & V of BERA & increased P100 latencies in VEP.The results of the electrophysiological tests of the patient showed that she had features of both medial & lateral medullary syndrome suggesting a lesion of both upper & middle medulla. The CT scan in this case was normal but conduction of MRI & CT guided angiography of posterior cerebral & vertebral arteries could have further localized the lesion causing this mixed symptomology

Clinical study of indirect optic nerve injury caused by motor vehicle accident / 中华急诊医学杂志

Objective To evaluate the curative effects of intravenous methylprednisolone (IVMP) during the conservative management for patients with indirect optic nerve injury (ONI),and to analyze the benefits of visual evoked potential (VEP) monitoring in prognosis assessment.Methods Among the 253 patients with cranial-facial injury,108 sufferred from optic nerve injury including 89 cases without optic nerve decompression treatment.These 89 patients were randomly divided into:group A,in which patients were given methylprednisolone intravenously for 7 days; and group B,in which patients without methylprednisolone treatment.The extent of and time required for eyesight recovery were recorded.VEP measurement was carried out in all cases.Results No differences in gender,age and BMI (Body Mass Index,all P ＞ 0.05) were observed.The incidence of ONI was higher in patients with motorcycle accident than that in those with car accident (P ＜0.01).In the motorcycle accidents,casualties wearing a helmet had lower incidence of ONI (P ＜ 0.01).Patients treated with methylprednisolone had a shorter recovery time (P ＜ 0.01) from blindness,however there was no difference in long-term outcome between group A and B.In patients with visual improvement in the “ non-extinguished” group,the amplitude and latency of the P wave of VEP were markedly ameliorated after the treatments (P ＜ 0.01).Conclusions Most of the ONI casualties in our study were resulted from motorcycle accidents,and wearing a helmet is an effective protection measure.The intravenous methylprednisolone (IVMP) showed no effect on improving the prognosis in patients with conservative treatment.The IVMP shortened the recovery time at the expense of increase in risk of complications.VEP examination is beneficial in prognosis assessment for non-operative ONI patients.The improvement of the amplitude and latency of P wave has close correlations with patients'visual recovery.

Effect of contrast and gaps between Vernier stimulus elements on sweep visual evoked potential measurements of human cortical Vernier responses

The present paper focuses on a classic hyperacuity, Vernier acuity-the ability to discriminate breaks in the collinearity of lines or edges on the order of only arcseconds of visual angle. We measured steady-state sweep visual evoked potentials (sVEPs) in response to 6 Hz periodic breaks in collinearity (Vernier offsets) in horizontal squarewave gratings. Vernier thresholds, estimated by extrapolating the amplitude of the first harmonic (1F) to 0 µV, were measured for gratings with 4%, 8%, 16%, 32%, 64%, and 80% contrast, with gaps of 0, 2, or 5 arcmin introduced between neighboring bar elements that formed the Vernier offsets. Thresholds for the 2F response component provided an estimate of motion thresholds. The data confirmed and extended evidence that the odd- and even-harmonic components reflect cortical activity of different neurons (i.e., neurons that respond asymmetrically to the periodic breaks in alignment and neurons that respond symmetrically to the local relative motion cue of the stimulus). Suprathreshold data (peak amplitude, response slope, and response phase at the peak amplitude) provided additional independent evidence of this notion. Vernier thresholds decreased linearly as contrast increased, with a slope of approximately -0.5 on log-log axes, similar to prior psychophysical results. The form of contrast dependence showed more similarity to measures of magnocellular ganglion cell spatial precision than measures from parvocellular ganglion cells. Our data thus support the hypothesis that magnocellular ganglion cell output from the retina has the requisite properties to support cortical calculation of Vernier offsets at a hyperacuity level...

Diagnostic Criteria of Pattern VEP in Adult Monocular Amblyopic Patients

PURPOSE: To suggest a diagnostic criteria of pattern visual evoked potential (VEP) in adult monocular amblyopic patients in comparison to normal subjects. METHODS: The medical records of patients' military service certificates from January 2000 to December 2011 were reviewed. The parameters of pattern VEP were analyzed by comparing monocular amblyopic patients with normal controls. RESULTS: This study included 47 monocular amblyopia and 39 normal control patients. All parameters of pattern VEP were statistically significantly different between monocular amblyopic eyes and normal eyes. The cut-off values for diagnosis of adult amblyopia using receiver operating characteristic (ROC) curve were 113.50 msec (P100 latency), 1.05 (ratio of P100 latency), 8.50 msec (interocular difference of P100 latency), and 5.25 microV (interocular difference of P100 amplitude). Cut-off value sensitivities were generally low: (51.1%, 70.2%, 53.2%, and 31.9%, respectively). CONCLUSIONS: The value of pattern VEP parameters had limitations due to low sensitivity and could be considered as ancillary diagnostic criteria when diagnosing amblyopia.

Pattern VEP in Adult Amblyopic Patients Requested From Military Service

PURPOSE: To evaluate the pattern VEP in adult amblyopic patients seen in consultation for ophthalmic evaluation as a past of physical examinations for conscription. METHODS: We retrospectively analyzed, 67 men, 20-year-old or older, who had pattern VEP done for the diagnosis of amblyopia from January 2004 to May 2009. P100 latency and P100 amplitude were analyzed. RESULTS: Thirteen patients were non-amblyopic, and 54 patients had amblyopia. Binocular amblyopia and monocular amblyopia were found in 23 and 31 patients, respectively. In the binocular amblyopic patients, four patients were hyperopic, seven patients were myopic, and 12 patients were astigmatic amblyopia. In the monocular amblyopic patients, 15 patients were anisometropic, 12 patients were strabismic, and four patients had organic amblyopia. The value of P100 latency and P100 amplitude were statistically significantly different between non-amblyopic and amblyopic eyes, with check size of 32x32. However, the types of amblyopia among the patients were not different at a statistically significant level. Visual acuity and P100 amplitude were significantly positively correlated. CONCLUSIONS: VEP might be a useful tool for diagnosis of adult amblyopia, especially using a 32x32 check size. This tool may impart the ability to decide relationship between amblyopia and visual acuity by analyzing P100 latency and amplitude values.

Electrophysiological evaluation of the safety of injection of tissue plasminogen activator into optic nerve in rabbits / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the safety of tissue plasminogen activator (tPA) intra optic nerve injection in rabbits. METHODS: Group 1 and 2 (6 eyes in each group) received injection of tPA 25μg and 12.5μg in 0.1mL balanced saline solution (BSS). Group 3 (6 eyes) received injection of 0 1mL BSS. Six eyes in group four as a normal control received no injection. The eyes were examined with slit lamp biomicroscope, indirect ophthalmoscope, visual evoked potentials (VEP) and electroretinography (ERG) at 1, 3, 7, 14 and 28 days after injection. RESULTS: No evidence of optic nerve or retinal toxicity or physical damage were revealed by ophthalmoscopy, VEP, and ERGs after the injection of tPA into the optic nerve. The means of the latency of the first peak of the VEP were 24.6±1.5, 24.1±1.9, 24.0±2.0 and 24.6±1.3mS respectively for the above specified groups (P=0.4112). The means of the amplitude of the first peak of the VEPs were 124±42, 145±41, 132±48 and 117±29μV respectively (P=0.0649). The means of the latency of a-waves were 6.0±0.4, 5.9±0.4, 5.9±0.5 and 5.8±0.3 mS respectively (P=0.6279). The means of the amplitude of a-waves were 110±14, 112±15, 110±16 and 108±11μV respectively (P=0.7248). The means of the amplitude of b-waves were 151±12, 148±14, 144±16 and 141±20μV respectively (P =0.0957).CONCLUSION: Injection of tPA upto 25μg in 0.1mL into optic nerve is well tolerated.

Neuromotor development and visual acuity in premature infants submitted to early visuo-motor stimulation

To investigate the effects of early visual stimulation on the development of tonus and posture control and of grating visual acuity of preterm infants, eight infants received visual stimulation that induced head motion during the first 6 months of life in weekly sessions. Their performance was compared with that of unstimulated preterm infants of same age (n = 6). Both groups were evaluated in the developmental scale of Gesell and had their grating visual acuity measured by swept visually evoked potentials (sweep-VEP). Visuomotor performance and adoption and maintenance of postures were significantly better for the stimulated group (p < .05) compared to the unstimulated group. There was no statistical difference between the two groups for the development of visual acuity. Visuo-motor and postural development improved with the early visuo-motor stimulation program. The lack of influence of this program in the development of visual acuity may be attributed to differences in the pathways involved in the processing of visual acuity of patterns and in the responses elicited by visuo-motor stimulation.

Clinical Ability of High Frequency Pattern VEP and Flicker ERG Examination to Detect Glaucomatous Visual Field Change

PURPOSE: We investigated whether pattern visual evoked potential (VEP) and flicker electroretinogram (ERG) are helpful in detecting the progression of glaucomatous field defect on standard automated perimetry. METHODS: We investigated 50 eyes with primary open-angle glaucoma (POAG) (n=18), glaucoma suspect (n=21), and control (n=11) tested with high frequency pattern VEP and flicker ERG at first visit in our hospital from 1998 to 2002. The results were applied as a prospective study. RESULTS: Thirteen eyes (study group) showed progressive defects, whereas 37 eyes (control group) showed no progression. The hit ratio, sensitivity and specificity were 78.0%, 84.6% and 75.7%, respectively, according to retino-cortical time (RCT) of 88 msec using the receiver operating characteristic curves. The mean survival time for the group with RCT less than 88.0 msec (41.95 months) was longer than that for the group with RCT more than 88.0 msec (31.0 months). The group which had more than 88.0 msec in RCT showed a hazard ratio of glaucomatous field defect progression of 7.855 compared to the other group (RCT: difference between P100 latency in VEP and a wave implicit time in ERG). CONCLUSIONS: Our study showed that high frequency pattern VEP and flicker ERG were significant in the progression of glaucomatous field defect.

Effects of MK-801 on rat F-VEPs during the critical period of visual development / 第三军医大学学报

Objective To investigate the effects of MK-801 on the rat F-VEPs during the critical period of visual plasticity.Methods We performed the F-VEPs examination in the normal Long Evans rats and the MK-801 treated rats on their postnatal days 14 and 28.Results After eye-opening,the latency of F-VEP main wave became shorter(P

Cortical Responses Evoked by the Light and Electricity in the Rabbit Retina

PURPOSE: By recording the electrically evoked potential (EEP) we tried to verify that focal electrical stimulation of retina sends a signal to the cortex that is similar to that elicited by light and also to investigate optimal stimulus parameters. METHODS: Five New Zealand white rabbits were placed under anesthesia. A tungsten bipolar stimulating electrode (diameter: 250 um) was placed on the vitreal surface of the retina. Cutaneous Ag/AgCl patch electrodes of VEP were used to record EEP. EEP was recorded at each stimulation. Focal visual evoked potentials (VEPs) were also recorded and compared to the focal EEP to ascertain cortical origin of the EEP, and similarities of the EEP to the VEP were determined. RESULTS: EEP recordings were elicited in 8 eyes. Current amplitudes which produced detectable responses ranged from 100 to 5000 micro A. In our best series, EEP amplitudes increased by 8 to 119 micro V in response to the current increasing from 100 to 1000 micro A. In comparing latencies of the EEP and focal VEP, the EEP latencies were 12~16 ms faster, which supports our EEP recording was done properly. CONCLUSIONS: EEPs obtained using VEP setting with adequate parameters of current duration and threshold level for the retinal implant showed that use of the EEP response is a good way to monitor the proper functioning of the retinal implant.

The Change of Visual Evoked Potential in Patients with Myopia in Correction of Refraction

OBJECTIVE: Multiple factors including age, sex, habituation, refraction, cooperation and technical variables are associated with P100 latency of Visual evoked potential (VEP). So we tried to evaluate the P100 latency of visual evoked potential according to refraction. METHOD: We studied 28 patients (12 males, 16 females) with myopia. Subjects were divided into 3 groups (mild, moderate, severe myopia) according to refraction and we evaluated the results of VEP studies. RESULTS: Mean values of refraction and latency (P100) of naked eyes were -4.27 D, 103.95 msec. and those of corrected eyes (in glasses) were -0.25 D, 100.59 msec. Respectively, in mild, moderate and severe myopia, the each P100 latency of naked eyes were 101.27 msec, 102.59 msec, 107.99 msec and those of corrected eyes were 98.33 msec, 100.58 msec, 102.19 msec respectively (p<0.05). There was significant negative correlation between refraction and P100 latency in myopia. CONCLUSION: Our results suggested that there were significant changes in VEP (P100 latency) according to refraction. In performing the VEP study, we should consider the refraction and visual acuity.

Visual Evoked Potentials in Healthy Preterm Infants

PURPOSE: The visual evoked potentials (VEPs) offer a window both on visual system function and on cerebral or neurologic function. The study was performed to evaluate the maturation of VEP in preterm infants and to present a guide to detect high risk neonates who can develop neurodevelopmental abnormalities. METHODS: The VEPs were recorded in response to binocular stimulus with light-emitting diode goggles. VEP recordings were analyzed in 37 healthy neonates who were followed longer than 6 months and neurodevelopmentally normal. RESULTS: 1) The peak latencies of N1 were 158.4+/-42.4 (msec), 159.4+/-40.6, 80.2+/-20.6, 52.4+/-12.0 from 34 to 42 weeks, respectively. 2) The peak latencies of P1 were 227.7+/-34.4 (msec), 187.0+/-35.4, 124.4+/-30.2, 148.3+/- 44.9 from 34 to 42 weeks, respectively. 3) The peak latencies of N2 were 315.4+/-49.9 (msec), 228.6+/-44.2, 205.5+/-69.3, 194.4+/- 89.9 from 34 to 42 weeks, respectively. 4) The peak latencies of P2 were 403.1+/-87.0 (msec), 275.4+/-61.5, 232.5+/-58.7, 255.1+/- 125.1 from 34 to 42 weeks, respectively. 5) The mean amplitude of N1-P1, P1-N2, N2-P2 were 5.3+/-6.8 (microvolt), 5.3+/-5.5, 5.5+/- 4.1 respectively. The peak latencies were inversely related to post-conceptional age (P<0.05). CONCLUSIONS: The peak latencies of each wave were decreased according to the post-conceptional age and these data reflect maturational changes in brain function.

P100 Latency in Normal Persons by Pattern Reversal VEP and Flash VEP

The Flash Light Emitted Diode Flash Visual Evoked Potential(Flash VEP) is useful when patients are unable to cooperate sufficiently for a Pattern Reversal Visual Evoked Potential(RP-VEP). In order to evaluate the clinical utility of Flash VEP, we performed the PR-VEP and Flash VEP in 208 eyes of 104 normal persons. The average P100 latency(LaP100) was analyzed according to check size, age, sex, and the laterality of the eye. The LaP100 of PR-VEP stimulated with 8 X 8(120' X 96'), 16 X 16(60' X 48'), 32 X 32 (30' X 24') and 64 X 64(15' X 12') check size were 98.88 +/- 7.57msec(mean S.D msec) , 97.68 +/- 7.44msec, 96.31 +/- 7.21msec, 101.20 +/- 7.81msec, respectively. The LaP100 of PR-VEP stimulated with 32 X 32 check size at 3rd, 4th, 5th, 6th and 7th decades were 93.95 +/- 5.61msec, 94.70 +/- 7.71msec, 92.92 +/- 6.28msec, 97.78 +/- 6.24 msec, 102.79 +/- 5.27msec, respectively. The LaP100 of PR-VEP remained relatively stable until over 6th decade when it increased significantly (p0.05), and between male and female(p>0.05) in the LaP100 of both VEP. These results showed that LaP100 of PR-VEP changes according to the check size and patient's age. We should interprete the LaP100 of PR-VEP or Flash VEP after the processing of averaging its P100 according to the patient's.

Postoperative Visual Results on Sellar and Parasellar Tumors

We reviewed the records of 28 patients who underwent transcranial(20 cases) or transsphenoidal(8 cases) surgery sellar and parasellar tumors. Both pre-and postoperative visual status(visual acuity and field) of each eye were analyzed under the rating system of Cohen, et al. The average duration of follow-up 3 months. The lesions encountered consisted of pituitary adenoma in 14 cases, craniopharyngioma in 5 cases, meningioma in 4 cases, chordoma in 3 cases, a dermoid cyst in 1 case, and an unspecified tumor in another case. All patients had objective signs of visual acuity or field defects preoperatively. Overall postoperative visual acuity and visual fields were normalized or improved in 73% and 71% of the eyes, respectively. The visual outcome of postoperative visual acuity was better in cases of craniopharyngioma(80%) than the other tumors. Visual evoked potentials(VEP) showed all postoperative improvement and was as helpful as visual fields in determining visual status. The visual outcome was better in patients with a shorter duration of symptoms and those with smaller tumors. Patients with lesser compromise of preoperative visual acuity had better outcome of postoperative visual acuity. However, the severity of preoperative visual field defects did not seem to influence postoperative field outcome. There also was no relationship between the presence of endocrine activity of the tumor and visual outcome. Patients who underwent transsphenoidal approach had either better visual acuity or field improvement than patients with transcranial approach.

Neonatal Neurosonographic Findings, Cerebral Doppler and Electrophysiological Findings in Infants with Motor Idsturbance

PURPOSE: Neurosonography, cerebral doppler and electrophysiological study are valuable in predicting neurodevelopmental outcome. The purpose of this study was to analyze characteristics of neonatal neurosonographic findigs, cerebral doppler and electrophysiological findings in infants withmotor disturbance. METHODS: The subjects were 33 infants hospitalized at Yonsei Severance Medical Center NICU from January, 1990 to December, 1992. 19 of these patients underwent neonatal cranial ultrasonogram and cerebral doppler and were diagnosed with cerebral palsy(CP) after Vojta treatment. 14 patients alose received Vojta treatment after discharge but showed only delayed development(DD). The cases were studied retrospectively and color doppler sonograpy was performed within 3 days of birth, 5-7 days after birth and weekly thereafter, and the cerebral blood flow velocity of the anterior cerebral artery was measured and comparison between normal pre-term and full-term infants done. Electroencephalogeraphy(EEG) and brainstem auditory evoked potential(BSAEP) were performed before discharge, with follow-up studies done only in cases showing abnormal findings, whereas visual evoked potential(VEP) was performed after discharge interhemispheric fissure was seen in 7 cases of CP and 1 cases of DD, showing a singnificatn frequency in CP, whereas there was no difference in the linear echogenecity of the basal ganglia. 4) Abnormal EEG was seen in 12 cases(63%) of CP group and 4 cses(29%) of DD group. The follow up EEG was normalized in all DD patients but CP patients conhtinues to show significant EEG abnormalities (7 cases out of 9). BSAEP and VEP abnormalities showed no significant difference between the 2 groups. 5) There was no significant difference in the average resistance index(RI) which was calculated from the cerebral blood flow velocity measured by cerebral doppler among normal newborns, CP and DD patents group. But average RI of CP patients was significantly lower than that of normal newborns, indicating an increase in cerebral blood flow in early life with severe neurologic sequelae. CONCLUSIONS: Neurosogography, cerebral doppler and electrophysiological studies performed in the perinatal period of children with motor disturbance show characteristic abnormal finding, with significant differences among childrem diagnosed with CP and DDD.

Neonatal Neurosonographic Findings, Cerebral Doppler and Electrophysiological Findings in Infants with Motor Idsturbance

PURPOSE: Neurosonography, cerebral doppler and electrophysiological study are valuable in predicting neurodevelopmental outcome. The purpose of this study was to analyze characteristics of neonatal neurosonographic findigs, cerebral doppler and electrophysiological findings in infants withmotor disturbance. METHODS: The subjects were 33 infants hospitalized at Yonsei Severance Medical Center NICU from January, 1990 to December, 1992. 19 of these patients underwent neonatal cranial ultrasonogram and cerebral doppler and were diagnosed with cerebral palsy(CP) after Vojta treatment. 14 patients alose received Vojta treatment after discharge but showed only delayed development(DD). The cases were studied retrospectively and color doppler sonograpy was performed within 3 days of birth, 5-7 days after birth and weekly thereafter, and the cerebral blood flow velocity of the anterior cerebral artery was measured and comparison between normal pre-term and full-term infants done. Electroencephalogeraphy(EEG) and brainstem auditory evoked potential(BSAEP) were performed before discharge, with follow-up studies done only in cases showing abnormal findings, whereas visual evoked potential(VEP) was performed after discharge interhemispheric fissure was seen in 7 cases of CP and 1 cases of DD, showing a singnificatn frequency in CP, whereas there was no difference in the linear echogenecity of the basal ganglia. 4) Abnormal EEG was seen in 12 cases(63%) of CP group and 4 cses(29%) of DD group. The follow up EEG was normalized in all DD patients but CP patients conhtinues to show significant EEG abnormalities (7 cases out of 9). BSAEP and VEP abnormalities showed no significant difference between the 2 groups. 5) There was no significant difference in the average resistance index(RI) which was calculated from the cerebral blood flow velocity measured by cerebral doppler among normal newborns, CP and DD patents group. But average RI of CP patients was significantly lower than that of normal newborns, indicating an increase in cerebral blood flow in early life with severe neurologic sequelae. CONCLUSIONS: Neurosogography, cerebral doppler and electrophysiological studies performed in the perinatal period of children with motor disturbance show characteristic abnormal finding, with significant differences among childrem diagnosed with CP and DDD.

Pattern-VEP in Child Amblyopia

We assessed the potential clinical usefulness of pattern-visual evoked potentials (=PVEP) in the diagnosis of amblyopia. 15 children with bilateral amblyopia, 64 children with unilateral amblyopia and 11 children without amblyopia participated. After estimating of visual acuity for each eye. PVEP were also obtained. Of the 15 bilateral amblyopic children 12 (80%) showed abnormally lower amplitudes than normal children and amplitudes of the rest 3 patients were in normal range and their visual acuity were relatively upper range, 0.5-0.6. Of the 64 unilateral amblyopic children 4 of 9(44.4%) children who had 2 line difference of interocular visual acuity, 2 of 3(67.7%) children who had 3 line difference and all children except 1 who had 4 or more line difference(99.9%) showed abnormal interocular amplitude difference ratio(=IADR). As a result, bilateral and unilateral amblyopia can be identified by PVEP amplitude and IADR and abnormal IADR shows that interocular visual acuity differences is over 3-4 lines. We thought that PVEP could be used to find the amblyopic eye and monitor the effect of treatment in preverbal children also.

Variability and application of VEP components in Transient VEP and Steady VEP

Before VEP use in clinics, we studied in statistical significance between borh eyes, intrasubject varciabilty intersubject variability (between incdividul) and changes of VEP cmponents between ignorance and attention in losujects (20eyes). There was no statistically significant difference between both eyes in each component of VEP and the variability of intersubjects was larger than that of intrasubjects. The smallest variability of intersubject was N1, P1 latency and that of intrasubject was PI latency in each component of VEP. When subjects were ignored, N1-P1, P1-N2 and steady VEP amplitude decreased significantly but N1, P1 and N2 latency were no significant difference.

Evoked Potentials in Brain Death

With 4 Channel Nocolet-CA 1000 clinical averager, somatosensory evoked potentials(SSEP), brainstem auditory evoked potentials(BAEP) and visual evoked potentials(VEP) were studied in 23 patients who fulfilled the clinical criteria for brain death. The results were as follows : 1) In SSEP, all patients had identifiable Erb's point wave and 11 out of 23 patients(48%) had cervical portion wave, but none of these patients had identifiable cortical portion wave. 2) In BAEP, 19 out of 23 patients(83%) had no identifiable BAEP waveforms, including wave I, and 4 patients(17%) had only wave I. 3) In VEP, 15 out of 23 patients(65%) had no identifiable VEP waveforms and 8 patients(35%) had short latency-low amplitude wave with no any of the longer latency components of central system origin.