Purpose To investigate the influence of ametropia on stereopsis and its mechanism by using the disparity evoked potential testing. Methods A new set of static random dot stereograms was utilized as a stimulation to elicit the disparity evoked potentials in 21 ametropes and 40 stereo normal subjects. Rezults The P250 wave,which was related to stereoscopic stimulation in ametropes,was recorded in both the ametropes and emetropic stereo normal persons in this series,and the characteristic changes of P250 wave with increasing visual disparity in ametropes were similar to those in normal subjects.The differences of mean amplitudes and latencies of P250 waves between myopes and hyperopes were not significant. Conclusion Ametropia in full correction dose not significanly affect the function of stereopsis. (Chin J Ocul Fundus Dis,1998,14:225-227)
OBJECTIVE In order to provide the scientific basis to find out a practical and effective method to evaluate the degree of muscle atrophy and a better method of prevention and treatment of skeletal muscle atrophy. METHODS Forty-two adult Spray-Dawley rats were used and the model of denervated gastrocnemius muscle was established by cutting off the tibial nerve. The muscle wet weight, diameter and cross section area of myocyte were measured. The motor end-plate, fibrillation potential amplitude and frequency of denervated skeletal muscle were observed. RESULTS The muscle wet weight rapidly reduced within 4 weeks. Afterwards, it maintained about 30 per cent of normal value, and the diameter and cross section area of myocyte progressively reduced. The motor end-plate slightly changed within 4 weeks, but its degeneration accelerated in 6 weeks and disappeared after 16 weeks. The fibrillation potential amplitude was maximum at 2 weeks and it progressively reduced after 12 weeks of muscle denervation. The changes of amplitude and frequency were consistent with the degeneration of end-plate. CONCLUSION The muscle wet weight, diameter and cross section area of myocyte, fibrillation potential amplitude and frequency could be considered as the morphological and electrophysiological indexes of muscle atrophy degree. It’s suggested that the repairing operation of peripheral nerve should be performed before the disappearance of motor end-plate.
purpose To study the visual electrophysiological changes in patients with chronic glomerulonephritis. Methods The visual evoked potentials(VEP) and electroretinogram(ERG) of 26 subjects with chronic glomerulonephritis in 51 eyes were recorded. Results Ours studies showed the patients with chronic glomerulonephritis had pathologic visual electrophysiologic abnormalities.The N 75 peak latency,b wave peak latency O 1 peak latency and total amplitude of OPs in chronic glomerulonephritis patients without fundus sign showed remarkable difference. Conclusion These changes suggested visual electrophysiological examination may be valuable in early diagnosis of retinal disfunction in patients with chronic glomerulonephritis. (Chin J Ocul Fundus Dis,1998,14:162-164)
Visual evoked potential (VEP) is a commonly used technique in neurology and ophthalmology in the process of disease diagnosis and treatment, which refers to the electrical signal transmitted by the visual pathway and recorded in the skull or cortex after stimulating the retina. The effect of monitoring and protection of vision in surgery near the visual pathway has attracted more and more attention recently. This article summarizes the experience and problems of intraoperative monitoring of VEP in terms of anesthesiology and instrument development, monitoring technology, and application innovation, and proposes future research directions. The purpose is to provide a reference for clinical application and research of intraoperative VEP monitoring.
Objective To compare the effect of electrode positions on multifocal visual evoked potential(mf-VEP). Methods Ten healthy individuals were tested with RETIscan multifocal VEP system 3.20, each individual was tested with four electrode positions: the active and reference electrode were placed 2.0 cm above and below the inion in Ch1；3.0 cm above and 4.5 cm below the inion in Ch2；2.0 cm on both right and left side of the inion in Ch3 and 4.0 cm on both right and left side of the inion in Ch4. The summed amplitudes of hemifield mf-VEP were analyzed and compared according to different electrode positions. Results The difference among summed amplitudes of the upper or lower hemifield mf-VEP recorded with Ch1、Ch2、Ch3 and Ch4 was statistically significant；and the difference between Ch2 and the other channels was statistically significant too. The difference among summed amplitudes of the horizontal sites whose amplitudes were small when recorded with Ch2 and summed amplitudes of the corresponding sites recorded with Ch3 and Ch4 were statistically significant；and the difference between Ch4 and the other channels was statistically significant too. Conclusions compared to Ch1、Ch3 and Ch4, Ch2 can make a better recording of mf-VEP. As for some sites, especially those along horizontal line, horizontal electrodes could improve the amplitudes of mf-VEP recorded with vertical electrodes，and Ch4 could do better to improve the mf-VEP recorded with Ch2 than Ch3. (Chin J Ocul Fundus Dis，2004，20：346-348)
OBJECTIVE: To investigate the characteristics and the pathologic classification of electrical-injury nerve using somatosensory evoked potential(SEP) technique. METHODS: SEP were detected and evaluated in 12 cases with electrical-injury nerve during operation, electrical stimulation was commenced from distal side of nerve where the structure of nerve looks normal under operating microscope, up to proximal side until evoking out a stable SEP predeterminate virtual value. Pathological examination and the following functional evaluation were compared with the values of SEP. RESULTS: At the site of nerve looking normal under operating microscope, perineurium appears normal or slightly thicken. But there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular. Vessel plexus is not seen. At SEP stabilizely evoked site, nervous construction is normal, there are visible interfascicular vessel plexus and connective tissue appears loose. Comparing SEP values with pathological section, amplitude and latency of SEP is positively correlative with the quality of nerve. Eight cases repaired with SEP technique to select the anastomosis site for nerve transplantation were followed up, two-point discrimination reached grade III (America hand surgery association criterion) within 62.5% cases. CONCLUSION: SEP technique is valuable method for functional evaluation of electrical- injury nerve which has a complicated pathology. The pathology of electrical-injury nerve can be classified into 4 types, type A: fibrosis of nerve; type B: nerve looking normal under operation microscope, perineurium appears thicken, and there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular, vessel plexus is rarely to see; type C: nerve looks normal, lymphocyte infiltration exists and it is obvious that there are many physalis-like, retrogressive construction in the section; type D: nervous construction is normal, there are visible interfascicular vessel plexus, and connective tissue appears loose, SEP always can be stably evoked.
Objective To analyze the symmetry of multifocal visual evoked potential (mfVEP) between both eyes in normal subjects. Methods The monocular mfVEP of both eyes in thirty-six normal subjects (72 eyes) was tested with VERIS Science 4.0. The stimulus was the pattern reversal dart array consisted of 60 sectors each included 16 black-white reverse patterns. The visual stimulation was controlled by the binary pseudo-random m-sequences and subtended approximately 25 degrees. Results There existed no statistically significant difference of P1 latencies and amplitudes between correspondent quadrant visual field of both eyes. The data difference of the ipsilateral quadrant visual fields was greater than those of the correspondent quadrant visual field. The comparison among four quadrant visual fields in right eye or left eye each showed that there was statistically significant difference of P1 latencies between the superionasal quadrant visual field and inferiotemporal or inferionasal quadrant visual fields. Conclusions The symmetry of normal mfVEP is more dominant in retina than that in visual cortex. (Chin J Ocul Fundus Dis, 2006, 22: 42-44)
Objective To observe the functional state of the optic nerve and discover the injury of visual pathway function in time under general ane sthesia. The flash visual evoked potential (F-VEP) was used to monitor visual function during orbital surgery. Methods A total of 252 out of 282 patients undergoing orbital surgery under general anesthesia were successfully monitored by F-VEP during the surgery. All patients were monitored by this method under the following conditions:consious state before operation, under general anaesthesia, during and after dissection of orbital tumor and at the end of operation. Results ①There was no significant difference of wave amplitude and latency under general anesthesia and consciousness condition. ②The amplitude and latency of F-VEP were normal in the orbital surgery withou toptic nerve injury. ③Pulling and oppression of optic nerve could cause temporary wave loss, but the wave recovered after removal of the pull and oppression. ④ The wave loss of F-VEP would occur immedicately when optic nerve was severe injured and its blood supply was deficient. Since the application of the visual function monitoring, 24 cases were treated in time during disturbance of visual function and no patient has unexpected visual loss during orbital surgery. Conclusion The intraoperative monitoring of F-VEP during orbital surgery can decrease the proportion of permanent visual loss caused by orbit al surgery, and help the surgical procedures go to function-anatomy stage from experience-anatomy stage. (Chin J Ocul Fundus Dis, 2001,17:260-263)
Objective To observe the changes of amplitude and latency of mini visual evoked optential (mini VEP) examinations in infants at different age.Methods A total of 84 healthy infants and adults (168 eyes) were randomly selected to underwent mini VEP. According to the age, all the individuals were divided into seven groups: A, 0-3 months; B, 4-6 months; C: 7-12 months; D: 1-3 years; E: 4-6 years; F: 7-12 years; G: adults (control). There were 12 individuals (24 eyes) in each group. By using the stimulater of mini VEP, the flash VEP was performed and the changes of amplitude and latency of P100 wave were recorded and analyzed.Results The average value of amplitude in group A was（7.39plusmn;1.79）mu;V which was the lowest, and the average latency was （137.45plusmn;7.64）ms which was the largest.At the same time, the average amplitude of P100 increased from group A to E (F=359.56); the average latency decreased from Group A to D（F=326.64）; the difference was significant (P＜0.01). The amplitude in group E, F, and G was high and no significant difference was found (F=2.39，P＞0.05);the latency in group D,E,F,and G was short with no significant difference (F=2.64，P＞0.05）.Conclusions With the growth of the infants' age, the amplitude of miniVEP increases and latency decreases; moreover, the latency reaches the normal adult level in advance of the amplitude of miniVEP.
The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P lt; 0.05), especially within 4 weeks. (P lt; 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.