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Pattern-reversal Visual Evoked Potential (pattern-reversal + visual_evoked_potential)

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Medical Sciences83%

Selected Abstracts

Pattern-reversal Visual Evoked Potentials in Patients with Newly Diagnosed Epilepsy

EPILEPSIA, Issue 8 2005
Bülent O. Genç
Summary:,Purpose: The possible occurence of evoked potential (EP) abnormalities in patients with newly diagnosed epilepsy has been little investigated. The main purpose of the present study was to investigate possible changes in pattern-reversal visual evoked potential (P-VEP) responses in newly diagnosed epilepsy patients. Methods: By using P-VEPs, latency values of the N75 and P100 together with amplitude values of P100 were recorded in newly diagnosed idiopathic epilepsy patients. The patients comprised two groups; nonphotosensitive (non-PS), and photosensitive (PS) patients. Results: Shortened N75 and normal P100 latencies of the P-VEP with higher than normal P100 amplitudes were detected in PS patients. In non-PS patients, N75 latencies of the P-VEPs were unaffected; however, P100 latencies were prolonged, and P100 amplitudes were unchanged. Conclusions: P-VEPs are different from those of controls in previously untreated idiopathic epilepsy patients. Results also indicate different P-VEP features in patients with and without photoparoxysmal responses. The changes might be the result of a disorder of one or more neurotransmitters or subtle morphologic damage such as microdysgenesis. [source]

Pattern-reversal visual evoked potentials in infants: gender differences during early visual maturation

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 5 2002
CA Malcolm BScN RN RGN
This paper investigates gender differences in the peak latency and amplitude of the P1 component of the pattern-reversal visual evoked potential (pattern-reversal VEP) recorded in healthy term infants. Pattern-reversal VEPs in response to a series of high contrast black and white checks (check widths 120,, 60,, 30,, 24,, 12,, 6,) were recorded in 50 infants (20 males, 30 females) at 50 weeks post-conceptional age (PCA) and in 49 infants (22 males, 27 females) at 66 weeks PCA. Peak latency of the major component, P1, was considerably shorter in female compared with male infants. Differences in head circumference do not entirely account for the gender differences in peak latency reported here. A gender difference in P1 amplitude was not detected. These findings stress the importance of considering gender norms as well as age-matched norms when utilizing the pattern-reversal VEP in clinical investigations. Studies including a wider range of ages are clearly necessary in order to establish whether the earlier peak latencies in female infants represents a difference in the onset or rate of visual maturation. [source]

Pattern-reversal Visual Evoked Potentials in Patients with Newly Diagnosed Epilepsy

EPILEPSIA, Issue 8 2005
Bülent O. Genç
Summary:,Purpose: The possible occurence of evoked potential (EP) abnormalities in patients with newly diagnosed epilepsy has been little investigated. The main purpose of the present study was to investigate possible changes in pattern-reversal visual evoked potential (P-VEP) responses in newly diagnosed epilepsy patients. Methods: By using P-VEPs, latency values of the N75 and P100 together with amplitude values of P100 were recorded in newly diagnosed idiopathic epilepsy patients. The patients comprised two groups; nonphotosensitive (non-PS), and photosensitive (PS) patients. Results: Shortened N75 and normal P100 latencies of the P-VEP with higher than normal P100 amplitudes were detected in PS patients. In non-PS patients, N75 latencies of the P-VEPs were unaffected; however, P100 latencies were prolonged, and P100 amplitudes were unchanged. Conclusions: P-VEPs are different from those of controls in previously untreated idiopathic epilepsy patients. Results also indicate different P-VEP features in patients with and without photoparoxysmal responses. The changes might be the result of a disorder of one or more neurotransmitters or subtle morphologic damage such as microdysgenesis. [source]

Ophthalmological, cognitive, electrophysiological and MRI assessment of visual processing in preterm children without major neuromotor impairment

DEVELOPMENTAL SCIENCE, Issue 5 2010
Michelle O'Reilly
Many studies report chronic deficits in visual processing in children born preterm. We investigated whether functional abnormalities in visual processing exist in children born preterm but without major neuromotor impairment (i.e. cerebral palsy). Twelve such children (< 33 weeks gestation or birthweight < 1000 g) without major neuromotor impairment and 12 born full-term controls were assessed at 8,12 years of age by means of ophthalmological assessment (visual acuity, colour vision, stereopsis, stereoacuity, visual fields, ocular motility, motor fusion), cognitive tests of visual-motor, visual-perceptual and visual-spatial skills and pattern-reversal visual evoked potentials (PR-VEPs). All participants also underwent magnetic resonance imaging (MRI) of the brain and neuromotor assessments. No significant differences were found between the groups on the ophthalmological, visual cognitive, neurological, neuromotor or MRI measures. The P100 component of the PR-VEP showed a significantly shorter latency in the preterm compared with the full-term participants. Whilst this P100 finding suggests that subtle abnormalities may exist at the neurophysiological level, we conclude that visual dysfunction is not systematically associated with preterm birth in the context of normal neurological status. [source]

Change of Excitability in Brainstem and Cortical Visual Processing in Migraine Exhibiting Allodynia

HEADACHE, Issue 10 2006
Koichi Shibata MD
Background.,Clinical and neurophysiological manifestations of information processing associated with central sensitization are little known. Allodynic migraine (AM) can be caused by the sensitization of trigeminal neuron, but no study has reported on AM between attacks using blink reflex (BR) and pattern-reversal visual evoked potentials (PVEPs). Objective.,We explored the characteristics of AM between attacks associated with central sensitization using BR and PVEP. Methods.,We recruited 13 patients with interictal AM and 15 patients with nonallodynic migraine (NA), and 30 healthy subjects (HS). BRs were obtained using paired pulses delivered at the interstimulus interval (ISI) of 150, 300, and 500 ms. The ratio of the area in the R2 of the second to R2 of the first shock was measured for each ISI. PVEP were recorded with 2 spatial frequencies (0.5 and 4.0 cpd) and 2 low and high contrasts (29% and 98%, respectively). Amplitudes of P100 were measured. Results.,For BR, there were no significant differences in the ratio of the area of the R2 between the sides of stimulation, and the sides of headache. AM patients had less suppression of the R2 at the ISI of 150 and 300 ms when compared with the NA patients and HS. For PVEP, at 0.5, there were significant differences of amplitude between AM patients and HS, and between NA patients and HS in low and high contrast. At 4.0 cpd, there were significant differences of amplitude between AM patients and HS in low contrast, and between AM patients and HS, and NA patients and HS in high contrast. In AM patients, there was a significant difference of amplitude ratio between 0.5 and 4.0 cpd. Conclusions.,Our BR and PVEP study showed that migraine patients exhibiting allodynia may show central sensitization of brainstem trigeminal neuron and have contrast modulating dysfunction during the cortical visual processing of striate and extrastriate on visual cortex in-between attacks. [source]