Despite positive prior results obtained by using event-related potentials (ERPs) in psychiatric patients, they are not routinely used in the clinical setting. This may in part be due to problems regarding a lack of transportable equipment availability. It can be difficult for these patients to repeatedly visit electrophysiological laboratories. To address this issue, we propose using a new, fully portable device for visually evoked potentials (VEP) and cognitive function assessment, that can be used for quick examinations (https://www.veppeak.com). Our device, called "VEPpeak", is built into a headset with a color LED visual stimulator. It weighs 390 g and is connected to a notebook (PC) with evaluation software via USB. In this pilot study, we verified the device's usability in 31 patients with schizophrenia. We used the oddball paradigm with the recognition of colors for the P300 wave and choice reaction time evaluation. The examination lasted only about ten minutes. The results indicated good reproducibility of large cognitive potentials (P300) with prolonged P300 latencies and reduced amplitudes in patients compared to 15 control subjects. The P300 latency and reaction time prolongation in patients correlated with their age and the sedative effect of the pharmacotherapy.
INTRODUCTION: We developed a new portable device called "VEPpeak" for the examination of visual evoked potentials (VEPs) to extend VEP examination beyond specialized electrophysiological laboratories and to simplify the use of this objective, noninvasive, and low-cost method for diagnostics of visual and central nervous system dysfunctions. METHODS: VEPpeak consists of a plastic headset with a total weight of 390 g containing four EEG amplifiers, an A/D converter, a control unit, and a visual LED stimulator built in the front, vertically adjustable peak. The device is powered and controlled via USB connection from a standard PC/notebook using custom software for visual stimuli generation and for VEP recording and processing. Up to four electrodes can be placed at any scalp location or in combination with two dry electrodes incorporated into the headset. External visual stimulators, such as a tablet, can be used with synchronization. Feasibility and validation studies were conducted with 86 healthy subjects and 76 neuro-ophthalmological patients including 67 who were during the same session also tested with a conventional VEP system. RESULTS: VEPpeak recordings to standard (pattern-reversal) and non-standard (motion-onset, red-green alternation) were robust and repeatable and obtained also in immobilized patients. Good comparability of results was achieved between VEPpeak and standard examination. Some systematic differences in peak latencies and amplitudes are consistent with differences in stimulus characteristics of the two compared systems. DISCUSSION: VEPpeak provides an inexpensive system for clinical use requiring portability. In addition to ISCEV standard VEP protocols, free choice of stimuli and bio-signal recordings make the device universal for many electrophysiological purposes.
Cíl: Zrakové evokované potenciály (visual evoked potentials; VEP) představují objektivní, neinvazivní a levnou diagnostickou metodu, zejména v neurooftalmologii. Mnoho diagnostických aplikací je však limitováno tím, že k jejich vyšetření se dosud používá robustní, obtížně transportovatelné zařízení, přičemž imobilní nebo jinak handicapovaní pacienti nemohou navštěvovat specializované laboratoře. Cílem naší práce bylo vyvinout snadno přenosný, levný VEP přístroj použitelný prakticky kdekoliv. Metodika: Všechny části posledního prototypu přístroje (vestavěný zrakový stimulátor, snímací elektrody, čtyřkanálový EEG zesilovač, analogově-číslicový převodník a řídicí jednotka) s celkovou hmotností 390 g jsou uloženy v náhlavním nosiči (umělohmotný „kšilt“ s upínacím páskem). Snímací a vyhodnocovací software pro natáčení a vyhodnocení VEP je použitelný na standardním notebooku (PC). Parametry přístroje splňují doporučení mezinárodních společností pro klinickou elektrofyziologii zraku a klinickou neurofyziologii, ale také umožňují nové aplikace dosud běžně nepoužívaných variant evokovaných potenciálů. Testování přístroje zatím proběhlo u 91 kontrolních osob a 135 neurooftalmologických pacientů. Výsledky: Pilotní studie prokázaly srovnatelné parametry VEP a diagnostickou senzitivitu jako u standardního zařízení (shoda nálezů v 93 % případů). Byla ověřena možnost použití přístroje v různých prostředích, u lůžka pacienta i pro laické samovyšetření. Závěr: Přenosný přístroj pro VEP výrazně zvyšuje dostupnost vyšetření, a tím umožňuje daleko širší diagnostické aplikace této metody.
Aim: Visual evoked potentials (VEP) represent an objective non-invasive and inexpensive diagnostic method, particularly in neuro-ophthalmology. A lot of possible diagnostic applications are limited because they are only examined with the use of robust equipment which is hardly transportable and immobile and handicapped patients cannot visit the specialized labs. The aim of our research work was the development of a portable inexpensive VEP device that could be used almost anywhere. Methods: All parts of the last prototype of the device (built-in visual stimulator, recording electrodes, 4-channel EEG amplifier, analog-digital converter, and control unit) with a total weight of 390 g are placed in a headset (plastic “shield” with an adjustable strap). The software for VEP recording and evaluation is used on a standard notebook (PC). The parameters of the device fulfill recommendations of the international societies for clinical electrophysiology of vision and clinical neurophysiology also enabling new applications of so far not routinely used variants of evoked potentials. Testing of the device was done so far in 91 control subjects and 135 neuroophthalmological patients. Results: Pilot studies proved comparable parameters of VEP and diagnostic sensitivity as in standard devices (equal results in 93% of cases). It was verified that the device is usable in various environments, at the patient’s bedside, and also for basic self-examination. Conclusion: The portable device for VEP significantly increases the availability of their examination and thus enables much broader diagnostic applications of this method.
- MeSH
- diagnostické techniky neurologické přístrojové vybavení statistika a číselné údaje MeSH
- diagnostické techniky oftalmologické přístrojové vybavení statistika a číselné údaje MeSH
- lidé MeSH
- zrakové evokované potenciály * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- klinická studie MeSH
- práce podpořená grantem MeSH
BACKGROUND: For patients with age-related macular degeneration (AMD), a special intraocular lens implantation partially compensates for the loss in the central part of the visual field. For six months, we evaluated changes in neurophysiological parameters in patients implanted with a "Scharioth macula lens" (SML; a center near high add + 10 D and peripheral plano carrier bifocal lens designed to be located between the iris and an artificial lens). METHODS: Fourteen patients (5 M, 9 F, 63-87 years) with dry AMD were examined prior to and at 3 days after, as well as 1, 2, and 6 months after, implantation using pattern-reversal, motion-onset, and cognitive evoked potentials, psychophysical tests evaluating distant and near visual acuity, and contrast sensitivity. RESULTS: Near visual acuity without an external aid was significantly better six months after implantation than before implantation (Jaeger table median (lower; upper quartile): 4 (1; 6) vs. 15 (13; 17)). Distant visual acuity was significantly altered between the pre- (0.7 (0.5; 0.8) logMAR) and last postimplantation visits (0.8 (0.7; 0.8) logMAR), which matched prolongation of the P100 peak time (147 (135; 151) ms vs. 161 (141; 166) ms) of 15 arc min pattern-reversal VEPs and N2 peak time (191.5 (186.5; 214.5) ms vs. 205 (187; 218) ms) of peripheral motion-onset VEPs. CONCLUSION: SML implantation significantly improved near vision. We also observed a slight but significant decrease in distant and peripheral vision. The most efficient electrophysiological approach to test patients with SML was the peripheral motion-onset stimulation, which evoked repeatable and readable VEPs.
- MeSH
- elektroretinografie MeSH
- implantace nitrooční čočky MeSH
- lidé MeSH
- makulární degenerace * MeSH
- nitrooční čočky * MeSH
- zraková ostrost MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: The aim of this neurophysiological study was to monitor changes in the visual and cognitive function of HIV-infected patients treated with combination antiretroviral therapy. METHODS: Eleven adult Czech HIV+ patients, with a mean age of 35 years and CD4 cell count ≥ 230 × 106 cells/L of blood at the time of enrollment, underwent four to six examinations over the course of 2.5 years to evaluate pattern-reversal and motion-onset visual evoked potentials (P-VEPs and M-VEPs), visually driven oddball event-related potentials (ERPs) and Montreal Cognitive Assessments. In addition to evaluating the intraindividual change in the observed parameters, we also compared patient data to data from eleven age- and gender-matched controls. RESULTS: We did not find any significant differences in P-VEPs between the patients and controls or in the paired comparison of the first and last visit. The only significant finding for P-VEPs was a linear trend in prolongation of the 20' P-VEP P100 peak time. In M-VEPs, we found a significant intergroup difference in the N160 peak time recorded during the first visit for peripheral M-VEPs only. During the last visit, all N160 peak times for patients differed significantly from those of the control group. The only intervisit difference close to the level of significance was for peripheral M-VEPs, which confirmed the trend analysis. No significant differences between patients and controls were found in the ERPs, but the P300 peak time showed a significant difference between the first and last visits, as confirmed by the trend. Patient reaction time was not significantly delayed at the first visit; however, it was prolonged with time, as confirmed by the trend. CONCLUSION: Our aim was to evaluate whether antiretroviral treatment in HIV+ patients is sufficient to preserve brain visual function. The optic nerve and primary visual cortex function tested by the P-VEPs seem to be preserved. The prolongation of the M-VEPs suggests an individually detectable decline in CNS function, but these changes did not show a progression during the follow-up. From a longitudinal perspective, the trends in peak time prolongation of the 20' P-VEP, peripheral M-VEP, ERP and reaction time suggest a faster decline than that caused by aging in healthy populations, as previously described in a cross-sectional study.
- MeSH
- antiretrovirové látky terapeutické užití MeSH
- dospělí MeSH
- elektroretinografie MeSH
- evokované potenciály fyziologie MeSH
- HIV infekce farmakoterapie patofyziologie MeSH
- kognice fyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- longitudinální studie MeSH
- mladý dospělý MeSH
- počet CD4 lymfocytů MeSH
- průřezové studie MeSH
- reakční čas fyziologie MeSH
- vnímání pohybu fyziologie MeSH
- zraková ostrost fyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- zrakové korové centrum fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: The goal of the current study was to explore visual function in virally suppressed HIV patients undergoing combined antiretroviral therapy (cART) by using pattern-reversal and motion-onset visual evoked potentials (VEPs). METHODS: The pattern-reversal and motion-onset VEPs were recorded in 20 adult HIV+ patients with a mean age of 38 years and CD4 cell counts ≥230 × 10(6) cells/L of blood. RESULTS: Nine out of 20 patients displayed VEP abnormalities. Pattern-reversal VEPs pathology was observed in 20% of subjects, and 45% HIV patients had impaired motion-onset VEPs. Five out of 16 neurologically asymptomatic HIV patients had prolonged motion-onset VEP latencies in both eyes. Four neurologically symptomatic patients displayed simultaneously abnormal motion-onset and pattern-reversal VEP latencies: monocular involvement was observed in two patients with Lyme and cytomegalovirus unilateral optic neuritis. Binocular involvement was noted in two patients with cognitive deficits. Correlation analysis between disease duration, CD4 cell count, HIV copies in plasma, MoCA and electrophysiological parameters did not show any significant relationships. CONCLUSIONS: The functional changes of the visual system in neurologically asymptomatic virally suppressed HIV patients displayed higher motion-onset VEP sensitivity than in standard pattern-reversal VEP examinations. This promising marker, however, has no significant association with clinical conditions. Further exploration is warranted.
- MeSH
- analýza rozptylu MeSH
- antiretrovirové látky terapeutické užití MeSH
- dospělí MeSH
- HIV infekce farmakoterapie imunologie patofyziologie virologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- počet CD4 lymfocytů MeSH
- rozpoznávání obrazu fyziologie MeSH
- virová nálož MeSH
- vnímání pohybu fyziologie MeSH
- zánět zrakového nervu patofyziologie virologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Standard pattern-reversal visual evoked potentials (VEPs) and motion-onset VEPs (M-VEPs) were tested in 19 dyslexics and 19 normal readers aged 7-13 years in order to evaluate the feasibility of M-VEPs for the objective diagnostics of a visual subtype of dyslexia, in which a dysfunction of the magnocellular subsystem/dorsal stream of the visual pathway is suspected. The set of VEPs consisted of the pattern-reversal VEPs with check sizes of 20', two types of translational motion (with low and high contrast) and two types of radial motion (in the full field or the periphery). While the P100 peak parameters in pattern-reversal VEPs did not differ between the group of dyslexics and controls, the group of dyslexics displayed significantly longer N2 latencies in all types of M-VEPs. Abnormal N2 latencies were found in 35-56% of dyslexics in different types of M-VEPs, with translational motion with high contrast being the most sensitive stimulation. A receiver operating characteristic analysis showed that the latencies of M-VEPs displayed higher discrimination potential than M-VEPs amplitudes. The study confirms a "magnocellular pathway/dorsal stream deficit" in approximately half of dyslexics.
- MeSH
- dítě MeSH
- dyslexie patofyziologie MeSH
- lidé MeSH
- mladiství MeSH
- senzorické prahy fyziologie MeSH
- studie případů a kontrol MeSH
- vnímání pohybu fyziologie MeSH
- zrakové dráhy patofyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- zrakové korové centrum fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
BACKGROUND: In adults, motion-onset visual evoked potentials (M-VEPs) with a dominant N2 peak represent a useful diagnostic tool. However, it is difficult to use this type of VEP in children because of the long maturation (up to 18 years) of M-VEPs, which is characterised by a gradual decrease in N2 peak latency and shape development. Moreover, in some children, M-VEPs are difficult to identify with standard stimuli. METHODS: We tested features of M-VEPs in 30 children (7-12 years) with the following set of standard stimuli used in our lab for examining adults ( https://web.lfhk.cuni.cz/elf ): low-contrast translation motion (TM) and expansion/contraction motion (ExCoM) in full field and in periphery (with central 20° masked). In 16 children, a high-contrast TM was also tested. RESULTS: With standard (low-contrast) stimuli, a common M-VEP to TM and to ExCoM was detected in 77 and 83 % of children, respectively. The M-VEPs to ExCoM in the periphery were detected in only 43 % of children. An abnormal dominant P1 peak was found in 9 % of VEPs to TM, 12 % of VEPs to full-field ExCoM and 14 % of VEPs to peripheral ExCoM. The M-VEPs to all low-contrast stimuli displayed large inter-individual latency variability (N2 peak latency differed for more than 100 ms). High contrast (more suitable for the non-mature magnocellular pathway) shortened M-VEP latencies and improved amplitudes. CONCLUSIONS: Our findings show that the maturation of motion perception in children is inter-individually variable, which limits the diagnostic use of M-VEPs.
- MeSH
- citlivost na kontrast fyziologie MeSH
- dítě MeSH
- lidé MeSH
- oči růst a vývoj MeSH
- senzorické prahy fyziologie MeSH
- vnímání pohybu fyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- zrakové korové centrum fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The manipulation of attention can produce mismatch negativity-like components that are not necessarily connected to the unintentional sensory registration of the violation of probability-based regularity. For clinical purposes, attentional bias should be quantified because it can vary substantially among subjects and can decrease the specificity of the examination. This experiment targets the role of attention in the generation of visual mismatch negativity (vMMN). The visual regularity was generated by a sequence of two radial motions while subjects focused on visual tasks in the central part of the display. Attentional load was systematically varied and had three levels, no-load, easy, and difficult. Rare, deviant, and frequent standard motions were presented with a 10/60 ratio in oddball sequences. Data from 12 subjects was recorded from 64 channels and processed. vMMN was identified within the interval of 142-198 ms. The mean amplitude was evaluated during the aforementioned interval in the parietal and fronto-central regions. A general linear model for repeated measures was applied to the mean amplitude with a three-factor design and showed a significant difference [F (1, 11) = 17.40, p = 0.002] between standard and deviant stimuli and between regions [F (1, 11) = 8.40, p = 0.01]; however, no significant effect of the task [F (2, 22) = 1.26, p = 0.30] was observed. The unintentional detection of irregularity during the processing of the visual motion was independent of the attentional load associated with handling the central visual task. The experiment did not demonstrate an effect of attentional load manipulation on mismatch negativity (MMN) induced by the motion-sequence, which supports the clinical utility of this examination. However, used stimulation paradigm should be further optimized to generate mismatch negativity that is stable enough to be usable not only for group comparisons but also for a single subject assessment.
- Publikační typ
- časopisecké články MeSH
We examined the visual and cognitive functions of a 72-year-old subject, KP, who recovered his sight after 53 years of visual deprivation. We used visual evoked potentials (VEPs) to pattern-reversal and motion-onset stimuli and cognitive responses (ERPs) during the oddball paradigm to assess the effect of long-term deprivation on a mature visual system. KP lost his sight at the age of 17 years, and light projection onto his right retina was restored at 71 years by a corneal implant. Nine months after sight recovery we recorded reproducible responses to all examined stimuli. The response to pattern reversal contained two P100-like peaks with the later peak being dominant and significantly delayed (260 ms) when compared to the P100s of two control subjects, to whom the stimuli were adjusted in size and contrast to mimic KP's vision. KP's motion-onset VEPs to full-field and peripheral stimuli had a characteristic shape with a well-defined N2 peak; however, both peaks were significantly delayed (262 and 272 ms) compared to control responses. Unlike the P100 and N2 peaks, which represent sensory detection, the P3b/P300 component of the ERP to a target event in the oddball paradigm was not further delayed. In spite of degraded vision and sensory deprivation lasting 53 years, KP displayed reproducible responses to all reported stimuli. Long-term visual deprivation and retinal detachment degraded KP's visual sensory processing, assessed by pattern-reversal and motion-onset VEPs, whereas the cognitive processing of appropriate visual stimuli was not compromised.
- MeSH
- časové faktory MeSH
- kognice fyziologie MeSH
- lidé MeSH
- obnova funkce fyziologie MeSH
- senioři MeSH
- senzorické prahy fyziologie MeSH
- slepota patofyziologie MeSH
- vnímání pohybu fyziologie MeSH
- zraková percepce fyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
