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P100 Latencies (p100 + latency)

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Medical Sciences100%

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]

EFFECTS OF A SINGLE, SHORT INTRAVENOUS DOSE OF ACETYL- l -CARNITINE ON PATTERN-REVERSAL VISUAL-EVOKED POTENTIALS IN CIRRHOTIC PATIENTS WITH HEPATIC ENCEPHALOPATHY

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2006
Massimo Siciliano
SUMMARY 1In animals and in cultured neurons, l -carnitine and acetyl- l -carnitine (ALCAR) have been shown to counteract some of the toxic effects of ammonia. In order to detect similar properties in humans, we studied neuronal function after ALCAR administration in cirrhotics with hepatic encephalopathy (HE). 2Eighteen cirrhotic patients with persistent HE and hyperammonaemia were investigated in the present study and six subjects with a prior transient ischaemic attack were used as controls. 3The prominent positive component that occurs approximately 100 msec after the pattern reversal (P100) latencies of visual-evoked potentials were used to evaluate neuronal function. At first, the P100 latency was measured in six cirrhotic patients with HE and in the six controls before the administration of 0.5 g ALCAR in 50 mL isotonic saline (infusion rate 10 mL/min) and 15, 30, 60 and 90 min later. 4A significant reduction in P100 latencies was identified 30 min after ALCAR infusion in HE patients, whereas no differences were observed in controls. 5Thereafter, the P100 latency was evaluated in the 12 other cirrhotic patients with HE only before and 30 min after ALCAR infusion. The mean of the P100 latencies measured in these subjects was significantly shorter after ALCAR infusion compared with values obtained before ALCAR administration (mean (SD) 130.78 5.50 vs 136.08 6.45 msec, respectively; P = 0.0013). 6The present study suggests that a single intravenous dose of ALCAR may transiently improve neuronal function in cirrhotic patients with persistent HE and hyperammonaemia. [source]

Effects of oestrogen replacement therapy on pattern reversal visual evoked potentials

EUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2000
H. Yilmaz
As a result of a regression in the ovarian functions, oestrogen level in circulation during the menopause drops to 1/50 of its value in the normal reproductive cycle. Excitatory oestrogen increases the sensitivity of the central nervous system to catecholamines by changing the opening frequency of voltage-related L-type calcium channels and augmenting the effect of glutamate; in addition it inhibits the formation of gamma-amino butyric acid (GABA) by the inhibition of glutamate decarboxylase enzyme. It is argued that oestrogen increases transmission in the optic pathways and that oestrogen is responsible for the shorter latency values and higher amplitudes of visual evoked potentials in women. We recorded the monocular pattern reversal visual evoked potentials (PRVEP) of both eyes of 54 post-menopausal women before treatment and of 30 of them after replacement therapy with Tibolon, and of 24 women receiving placebo treatment. The explicit values of P100 latency of right and left eyes before treatment were 98.8 ± 3.5 and 99.0 ± 3.3 ms, respectively. The explicit values of P100 latency of right and left eyes after placebo treatment were 98.6 ± 3.7 and 98.8 ± 4.0, respectively. The explicit values of P100 latency of right and left eyes after replacement treatment were 94.6 ± 3.7 and 94.8 ± 4.0, respectively. We found a statistically significant decrease in the mean PRVEP latencies and a statistically significant increase in mean amplitudes after replacement treatment (P < 0.001) compared with those before treatment and those after placebo treatment. We attributed the changes in PRVEP values after replacement treatment to the action of Tibolon, which acted as a natural sex steroid and speeded the visual transmission time via the widespread receptors in the central nervous system. It is concluded that PRVEP is an objective electrophysiological assessment method in evaluating the efficiency of hormone replacement therapy in post-menopausal women. [source]

Visual and brainstem auditory evoked potentials in children with headache

PEDIATRICS INTERNATIONAL, Issue 5 2008
Bulent Unay
Abstract Background: Headache is a common problem in the pediatric population. The purpose of the present study was to evaluate visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) in children with headache. Methods: Thirty-seven children fulfilling the International Headache Society Criteria for a diagnosis of migraine, 35 children with tension-type headache and 40 healthy children (control group) were enrolled in the study. Results: The mean age of patients and controls was 10.4 years. P100 latency and amplitudes of migraine patients were significantly higher than children with tension-type headache and control subjects. Children with tension-type headache also had higher P100 latency and amplitude values than control subjects but there was no statistical difference. BAEP responses were similar between all groups. Conclusion: Measurement of VEP latency and amplitude is a valuable and reliable test for the diagnosis of migraine and can be used safely in childhood. [source]

EFFECTS OF A SINGLE, SHORT INTRAVENOUS DOSE OF ACETYL- l -CARNITINE ON PATTERN-REVERSAL VISUAL-EVOKED POTENTIALS IN CIRRHOTIC PATIENTS WITH HEPATIC ENCEPHALOPATHY

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2006
Massimo Siciliano
SUMMARY 1In animals and in cultured neurons, l -carnitine and acetyl- l -carnitine (ALCAR) have been shown to counteract some of the toxic effects of ammonia. In order to detect similar properties in humans, we studied neuronal function after ALCAR administration in cirrhotics with hepatic encephalopathy (HE). 2Eighteen cirrhotic patients with persistent HE and hyperammonaemia were investigated in the present study and six subjects with a prior transient ischaemic attack were used as controls. 3The prominent positive component that occurs approximately 100 msec after the pattern reversal (P100) latencies of visual-evoked potentials were used to evaluate neuronal function. At first, the P100 latency was measured in six cirrhotic patients with HE and in the six controls before the administration of 0.5 g ALCAR in 50 mL isotonic saline (infusion rate 10 mL/min) and 15, 30, 60 and 90 min later. 4A significant reduction in P100 latencies was identified 30 min after ALCAR infusion in HE patients, whereas no differences were observed in controls. 5Thereafter, the P100 latency was evaluated in the 12 other cirrhotic patients with HE only before and 30 min after ALCAR infusion. The mean of the P100 latencies measured in these subjects was significantly shorter after ALCAR infusion compared with values obtained before ALCAR administration (mean (SD) 130.78 5.50 vs 136.08 6.45 msec, respectively; P = 0.0013). 6The present study suggests that a single intravenous dose of ALCAR may transiently improve neuronal function in cirrhotic patients with persistent HE and hyperammonaemia. [source]