scholarly journals Pattern Reversal Visual Evoked Potential and Cognitive Functions in Subclinical Hypothyroid Subjects

2016 ◽  
Vol 07 (S 01) ◽  
pp. S046-S051
Author(s):  
Pooja Jaiswal ◽  
Yogesh Saxena ◽  
Rani Gupta ◽  
Rajeev Mohan Kaushik
Keyword(s):  
Cognitive Functions ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Electrophysiological Study ◽  
Thyroid Stimulating Hormone ◽  
Pattern Reversal ◽  
Cross Sectional ◽  
Mean Values ◽  
Significant Difference ◽  
Visual Evoked

ABSTRACT Background: Central nervous system (CNS) involvement is insidious and may occur early in subclinical hypothyroid (SCH) state which can be picked up by electrophysiological study. This study aims to record visual evoked potential (VEP), event-related latency and cognitive functions, and find their association with the levels of serum thyroid-stimulating hormone (TSH) in patients with SCH. Materials and Methods: In this cross-sectional study, 36 adult SCH patients and an equal number of age- and sex-matched euthyroid controls were included. Pattern reversal VEP, visual reaction time (RT), digit spanning test, and AB clock test (ABCT) were done in both SCH cases and euthyroid controls. The observed values were analyzed for comparison of mean values between the groups and correlation of recorded variables with the levels of serum TSH. Results: SCH cases showed a higher P100 (VEP) latency in both the right (103.2 ± 12.3 vs. 102.7 ± 6.8 ms) and left eye (101.1 ± 9.1 vs. 96.2 ± 10.7 ms) as compared to controls, but the difference was statistically insignificant. A significant delay in RT was observed on visible spectra of light in SCH cases (P < 0.001). Digit spanning score (forward and backward) in SCH cases was significantly lower than controls (P < 0.001), and a lower standardized score (<124 or <95th percentile) was significantly associated with SCH state (P = 0.027). No significant difference was observed in visuospatial domain by ABCT between both the groups although the median score was lower in SCH cases. Only digit spanning score showed a significant negative correlation with TSH levels (r = −0.4; P = 0.001). Conclusion: Decline in working memory and RT to visual stimuli is an evidence of the involvement of CNS in SCH. Prolonged latency in VEP may depend on the duration of SCH.

scholarly journals Low-contrast Pattern-reversal Visual Evoked Potential in Different Spatial Frequencies

2020 ◽  
Author(s):  
Homa Hassankarimi ◽  
Ebrahim Jafarzadehpur ◽  
Alireza Mohammadi ◽  
Seyed Mohammad Reza Noori
Keyword(s):  
Wavelet Transform ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Pattern Reversal ◽  
Contrast Level ◽  
Low Contrast ◽  
Time Frequency ◽  
Spatial Frequencies ◽  
Significant Difference ◽  
Visual Evoked

Purpose: To evaluate the pattern-reversal visual evoked potential (PRVEP) in lowcontrast, spatial frequencies in time, frequency, and time-frequency domains. Methods: PRVEP was performed in 31 normal eyes, according to the International Society of Electrophysiology of Vision (ISCEV) protocol. Test stimuli had checkerboard of 5% contrast with spatial frequencies of 1, 2, and 4 cycles per degree (cpd). For each VEP waveform, the time domain (TD) analysis, Fast Fourier Transform(FFT), and discrete wavelet transform (DWT) were performed using MATLAB software. The VEP component changes as a function of spatial frequency (SF) were compared among time, frequency, and time–frequency dimensions. Results: As a consequence of increased SF, a significant attenuation of the P100 amplitude and prolongation of P100 latency were seen, while there was no significant difference in frequency components. In the wavelet domain, an increase in SF at a contrast level of 5% enhanced DWT coefficients. However, this increase had no meaningful effect on the 7P descriptor. Conclusion: At a low contrast level of 5%, SF-dependent changes in PRVEP parameters can be better identified with the TD and DWT approaches compared to the Fourier approach. However, specific visual processing may be seen with the wavelet transform.

Visual Evoked potential signal processing and analysis for normal and galucomic eyes

2015 ◽  
Vol 8 (2) ◽  
pp. 2106-2121
Author(s):  
Hamed Ibrahem Abdelkader ◽  
Mona Abdelkader ◽  
Mohammed Kabeel ◽  
Malak Alya
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Optic Tract ◽  
Pattern Reversal ◽  
Blue Color ◽  
Check Size ◽  
Retinal Stimulation ◽  
Normal Individuals ◽  
Visual Evoked

Visual evoked potentials (VEPS) are obtained from optic tract by recording the evoked potentials generated by retinal stimulation. The flash VEP (FVEP) is used less frequently than pattern reversal VEP (PRVEP) because; it shows great variation in both latency and amplitude. The present study was undertaken to evaluate the effect of change of wavelength of flash and change of check size on the parameters of visual evoked potential (amplitude and latency) in normal individuals and glaucoma patients. The group of healthy subjects in the age of 20-45 years while the group of glaucoma subjects where  in the age of 25-50 years.  The two groups were exposed to flash VEP with white light and blue color and they also were exposed to checks subtending a visual angles of 15, 30,60 and 120 minutes of arc. The measured data were statistically analyzed and summarized by histograms. The interindividual and intraindividual in latencies and amplitudes for FVEP were assessed using  the coefficient of variation (COV). In conclusion, monochromatic flash VEP was preferred than white as there were minimal inter and intra individual variation of latencies and amplitudes. The most preferred check size in PRVEP was 120' for  the two groups.  

Primary Presenile Dementia: The Use of the Visual Evoked Potential as a Diagnostic Indicator

1985 ◽  
Vol 147 (5) ◽  
pp. 532-539 ◽  
Author(s):  
Graham F. A. Harding ◽  
Christine E. Wright ◽  
Arnold Orwin
Keyword(s):  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Cortical Atrophy ◽  
Control Group ◽  
Pattern Reversal ◽  
Presenile Dementia ◽  
The Difference ◽  
Pattern Reversal Stimulation ◽  
Diagnostic Indicator ◽  
Visual Evoked

The use of the flash and pattern reversal visual evoked potential (VEP) in the diagnosis of primary presenile dementia was investigated. The results from 20 patients with primary presenile dementia were compared with those from a control group of normals of equivalent age and from a control group of 20 patients with cortical atrophy but no dementia. Presenile dementia caused a slowing of the major positive (P2) component of the VEP to flash stimulation. However, the VEP to pattern reversal stimulation (P100) was of normal latency. The difference between these two latencies characterises this unusual combination of results and is found to be a more specific diagnostic indicator of primary presenile dementia than the EEG or CT scan.

Pattern-Reversal Visual Evoked Potential in Children With Congenital Zika Syndrome

2021 ◽  
Vol 58 (2) ◽  
pp. 78-83
Author(s):  
Luan F. B. Almeida ◽  
Marisa Kattah ◽  
Liana O. Ventura ◽  
Adriana L. Gois ◽  
Camilla Rocha ◽  
...  
Keyword(s):  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Pattern Reversal ◽  
Congenital Zika Syndrome ◽  
Visual Evoked

Pattern-Reversal Visual Evoked Potential on Smart Glasses

2020 ◽  
Vol 24 (1) ◽  
pp. 226-234 ◽  
Author(s):  
Rossana Terracciano ◽  
Alessandro Sanginario ◽  
Simona Barbero ◽  
Davide Putignano ◽  
Lorenzo Canavese ◽  
...  
Keyword(s):  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Pattern Reversal ◽  
Smart Glasses ◽  
Visual Evoked

scholarly journals Effect of smoking on visual evoked potential (VEP) and visual reaction time (VRT)

2020 ◽  
Vol 11 (2) ◽  
pp. 9-13
Author(s):  
Karishma Rajbhandari Pandey ◽  
Dipesh Raj Panday ◽  
Nirmala Limbu ◽  
Bhupendra Shah ◽  
Kopila Agarwal
Keyword(s):  
Reaction Time ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Smoking Status ◽  
Statistical Significance ◽  
Visual Reaction Time ◽  
Significant Difference ◽  
Visual Reaction ◽  
Pattern Vep ◽  
Visual Evoked

Background: Nicotine in tobacco smoke causes demyelination. Again, hypoxia in long-term smokers is linked to neuropathy. Visual receptors are early sufferer of neuropathy. Visual-Acuity & other ocular tests often fail to detect subtle changes of neuropathy which, however, can be detected by VEP test. Literature review shows that changes in VEP come earlier than PFT changes in smokers. Ironically, smokers claim that smoking improves their reaction time, which can be assessed by VRT. Aims and Objective: To relate smoking status with VEP and VRT. Materials and Methods: Fifty-six subjects (smoker group = 28 & non-smoker group = 28), whose age & sex were matched, were included in the study. Their PFT, pattern VEP of both eyes & VRT were recorded. The data were compared between the two groups using unpaired t-test, considering statistical significance at p<0.05. Results: The FVC (4.35±0.83 vs. 5.32+1.18 l, p=0.022), FEF 25% (7.40+2.38 vs. 8.74+3.90 l/s, p=0.019) & FEF 50% (6.11+1.52 vs. 7.74+2.57, p= 0.010) were significantly lower in smokers compared to nonsmokers. There was no significant difference in P100 wave latency of VEP. But, VRT of smokers were significantly shorter (431.69+60.29 vs. 441.14+123.54 ms, p=0.010). Conclusion: Smokers have shorter visual reaction time and similar visual evoked potential as compared to non-smokers.

Effect of Head Circumference and Gender on Pattern Reversal Visual Evoked Potential

2016 ◽  
Vol 3 (3) ◽  
pp. 107
Author(s):  
Kuldip Singh Bhatia ◽  
Anil Kumar ◽  
Ali Ahanger ◽  
Pradeep Shingal ◽  
Vijay Kumar Roy
Keyword(s):  
Head Circumference ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Pattern Reversal ◽  
And Gender ◽  
Visual Evoked
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