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
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.
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- 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
