Résumé
Purpose: To study the effect of refractive errors on pattern visual evoked potential (VEP) recordings in the pediatric population. Methods: This cross?sectional observational study assessed 240 eyes of 120 participants attending the outpatient department of a tertiary care center in North India. Participants were between 8 and 18 years of age; 30 participants each were recruited into four groups, namely emmetropia, myopia, hypermetropia, and amblyopia. They were then subjected to pattern reversal VEP, with P?100 amplitude and latency recorded for each participant. Results: The emmetropic group in this study provided normal values of P?100 parameters, namely P?100 latency and P?100 amplitude with readings of 115.78 ± 10.19 ms and 11.11 ± 4.08 ?V, respectively. P?100 amplitude was significant compared to P?100 latency in detecting the presence or absence of a specific type of refractive error. It was found that there was a significant association between severity of myopia and P?100 latency (both unaided and aided) with P < 0.05. The severity of hypermetropia showed a significant association with P?100 amplitude (unaided) (P < 0.05). Receiver operating characteristics analysis revealed P?100 amplitude to be a good predictor of refractive error and the cut?offs were calculated. Conclusion: The P?100 parameters of the pediatric Indian population were comparatively higher than conventional values. P?100 latency seemed to better correlate with myopia, while hypermetropia correlated with P?100 amplitude. P?100 amplitude appears to be the most significant predictor of the presence of refractive error in an individual.
Résumé
Objective: To assess the sensitivity, specificity, and predictive value of EEG as a diagnostic and prognostic tool in the febrile seizures. Method: This study was conducted on 50 consecutive children with febrile seizures attending the pediatric OPD of a tertiary care hospital. The children were prospectively identified and EEG was carried out on two occasions. First EEG was done within one week of febrile seizure episode and second EEG was done after 03 months of first EEG. EEG records were obtained with the standard international protocols for duration of 35 minutes which included 25 minutes of sleep record in all the children. Photic stimulation, hyperventilation and sleep deprivation were used as activation procedures. Descriptive analysis of EEG tracings was done in terms of background activity and presence of abnormal waveforms. Result: Paroxysmal EEG abnormalities were present in 54% of children. Most common epileptiform discharges were of generalized epileptic discharge followed by focal polyspikes. Sleep deprivation was the most effective activation procedure in evaluating febrile seizure with abnormal epileptiform discharge patterns. Validity measures of EEG in febrile seizure were found to have 90% sensitivity, 70% specificity, 72% positive predictive value and 88% negative predictive value within 95% confidence interval. Conclusion: EEG is a sensitive method for identifying and quantifying electrical activity in febrile seizures. EEG is useful as a diagnostic and prognostic tool in febrile seizures and can provide information regarding presence of abnormalities, degree of encephalopathy and electrographic features but like all diagnostic tool it is not fully infallible and requires further alternative diagnostic and clinical support.
Résumé
Objectives: To explore the EEG changes associated with psychological stress state. Methods: The study was conducted on 34 healthy male student volunteers. The intervention consisted of psychological stress, which was induced by asking the participants to play a pre-decided stressful computer game. Physiological markers of psychological stress were assessed using galvanic skin response (GSR) and heart rate (HR). Electroencephalography (EEG) was recorded from 19 scalp locations according to 10- 20 international system of electrode placement. Results: Computer game served as model of lab stressor and was associated with a significant increase in physiological markers (GSR & heart rate) of stress response. Psychological stress was associated with increased absolute power in theta, lower 1 alpha and gamma bands & decreased power in upper alpha and beta bands. Lower 2 alpha band power remained unchanged. Conclusions: Certain types of computer games serve as a model of lab stressor and are associated with physiological and psychological stress and have unique electroencephalographic correlates. The EEG correlates of mental stress are unique superimposed pattern of various cognitive domains. With sustained and continuing stress resulting from computer game attention, alertness and performance starts declining.