Prolonged N200 is the early neurophysiologic change in the patient with minimal hepatic encephalopathy.

BACKGROUND: In neurophysiological studies, P300, is well known for reflecting early cognitive impairment in minimal hepatic encephalopathy (MHE). Although P300 is investigated extensively, other early event-related potential (ERP) parameters have not been studied in MHE. METHODS: The subjects were 21 adult cirrhotic patients without clinical encephalopathy and 29 normal controls. For neuropsychological testing, number connection tests, A and B (NCT-A, NCT-B), the line tracing test, the serial dotting test (SDT), and the digit symbol test (DST) were performed. For ERP testing, auditory oddball paradigms were used. The N100, P200, N200, and P300 parameters were measured. RESULTS: Cirrhosis had longer neuropsychological performance scores on NCT-A, SDT, and DST than the control group. In neurophysiological test, cirrhotic patients showed longer latencies for N100, P200, N200, and P300 than the control group. Although P300 alteration was not seen in patients without MHE compared to the control group (325.4±43.3 vs. 345.21±35.1, p=0.25), N200 latency was significantly prolonged in cirrhotic patients without MHE compared to the healthy group (242.1±30.3 vs. 259.58±33.3, p=0.006). N200 also showed good correlation with psychometric hepatic encephalopathy score and critical flicker frequency. CONCLUSIONS: N200 is a useful tool for assessing early changes of cognitive dysfunction in cirrhosis. It suggests that slower auditory cortical processing is the first sign of cerebral deterioration in patients with hepatic encephalopathy.

Timely event-related synchronization fading and phase de-locking and their defects in migraine.

OBJECTIVE: To investigate the characteristics of event-related synchronization (ERS) fading and phase de-locking of alpha waves during passive auditory stimulation (PAS) in the migraine patients. METHODS: The subjects were 16 adult women with migraine and 16 normal controls. Electroencephalographic (EEG) data obtained during PAS with standard (SS) and deviant stimuli (DS) were used. Alpha ERS fading, the phase locking index (PLI) and de-locking index (DLI) were evaluated from the 10 Hz complex Morlet wavelet components at 100 ms (t100) and 300 ms (t300) after PAS. RESULTS: At t100, significant ERS was found with SS and DS in the migraineurs and controls (P=0.000). At t300 in the controls, ERS faded to zero for DS while in the migraineurs there was no fading for DS. In both groups the PLI for SS and DS was significantly reduced, i.e. de-locked, at t300 compared to t100 (P=0.000). In the migraineurs, the DLI for DS was significantly lower than in the controls (P=0.003). CONCLUSION: The alpha ERS fading and phase de-locking are defective in migraineurs during passive auditory cognitive processing. SIGNIFICANCE: The defects in timely alpha ERS fading and in de-locking may play a role in the different attention processing in migraine patients.

Neurological and muscular manifestations associated with influenza B infection in children.

BACKGROUND: Influenza viruses have been associated with various neurological and muscular symptoms. The aim of this study was to evaluate the pediatric neurological and muscular manifestations of influenza B during a 5-month epidemic at a single center. METHODS: We retrospectively reviewed the medical records of 355 pediatric patients with laboratory-confirmed influenza B infection. RESULTS: Neurological and muscular symptoms were exhibited by 28 patients (7.9%). The mean age was 48.7 ± 25.2 months. The mean time between respiratory symptoms and neurological symptoms was 2.2 ± 1.5 days. The most common symptom was seizure (19/28, 67.9%), followed by myositis (5/28, 17.9%), increased intracerebral pressure (1/28, 3.6%), delirium (1/28, 3.6%), and severe headache (1/28, 3.6%). There was one severe case of meningitis with myocarditis (1/28, 3.6%). All seizures were febrile: 15 simple febrile seizures (78.9%), three complex febrile seizures (15.8%), and one febrile status epilepticus (5.3%). The mean age of nine patients with their first seizures was 37.9 ± 22.2 months, which was older than the typical age of onset for febrile seizure. All the patients, except one, were treated with oseltamivir. There were no deaths or chronic debilitating sequelae. CONCLUSIONS: The neurological and muscular complications of influenza B infection in children are relatively mild, and febrile seizure is the most common. However, clinicians should be alert to the possibility of rare severe complications during influenza B outbreaks.

Use of inhaled iloprost in an infant with bronchopulmonary dysplasia and pulmonary artery hypertension.

Pulmonary artery hypertension is a common cardiovascular complication in preterm infants with bronchopulmonary dysplasia which is associated with increased morbidity and mortality. Inhaled iloprost is used as a therapeutic option in pulmonary hypertension, especially in adults. There have been but a few reports on the use of iloprost for neonates and infants. We report the case of a 5 month-old-male infant who received neonatal intensive care for 4 months due to respiratory distress syndrome and prematurity, during which he developed bronchopulmonary dysplasia. Echocardiography showed severe pulmonary hypertension. The initial treatment included respiratory support with high frequency oscillatory ventilation (HFOV); however, his clinical condition did not improve. Inhaled iloprost with sildenafil, an oral phosphodiesterase-5 inhibitor, was thus used. With the administration of iloprost and sildenafil, his condition improved and he was weaned from oxygen. Our clinical experience suggests that iloprost is a promising therapy for pulmonary hypertension, especially when inhaled nitric oxide is unavailable.

Low resolution electromagnetic tomography analysis of ictal EEG patterns in mesial temporal lobe epilepsy with hippocampal sclerosis.

OBJECTIVE: To investigate the difference in the spatial distribution of scalp initial ictal discharge (IID) patterns in mesial temporal lobe epilepsy with hippocampal sclerosis (HS-MTLE). METHODS: Scalp ictal EEG data in 22 seizure-free patients after temporal lobectomy with amygdalo-hippocampectomy were classified as follows: a regular 5-9Hz rhythm with a restricted temporal/subtemporal distribution (type 1, 11 patients), or an irregular 2-5Hz rhythm with a widespread fronto-temporal distribution (type 2, 11 patients). EEG data were fragmented into segments of 1.28s, both at ictal onset and at baseline. The LORETA solution of three frequency bands was compared between ictal and baseline using statistical non-parametric mapping (p<0.01). RESULTS: The LORETA solution of 5-9Hz in type 2 had wider cortical activity in the ipsilateral fronto-temporal area, compared to type 1 with activation of the ipsilateral focal mesial and lateral temporal regions. The LORETA solution of 10-13Hz in both types showed increased activity in the fronto-temporal area, which was wider in type 2 than type 1. Increased cortical activity of <5Hz was not observed in type 1, whereas increased cortical activity was observed in the bilateral anterior frontal area in type 2. CONCLUSIONS: The cortical source distribution in HS-MTLE may depend on scalp IID frequency. The neural generators of 5-13Hz may be important for the formation of the ictal onset zone in both ictal patterns. SIGNIFICANCE: Spatial distributions in HS-MTLE patients differ with scalp IID frequency.

Rotavirus infection in neonates at a university hospital in Korea.

To develop measures to prevent neonatal rotavirus infection, we carried out rotavirus surveillance testing on all the newborns who were admitted to a newborn nursery in Korea during 1 year. We investigated the characteristics of neonatal rotavirus infection and found that it occurred throughout the year with the G4P[6] strain exclusively. Most newborns were infected nosocomially and showed no symptoms. We concluded that rotavirus might be transmitted from asymptomatic infected newborns who were born outside the hospital. We recommend isolation and rotavirus surveillance testing for all transfer patients.

Measuring depth of anesthesia with EEG and ECG in children.

BACKGROUND: Heart rate is tightly controlled by brain. If activity of brain and electroencephalograph (EEG) are changed by anesthetics, electrocardiograph (ECG) might be changed. We investigated whether there is a correlation between EEG and ECG, ECG could replace EEG as a monitor for depth of anesthesia. METHODS: We recruited 50 patients, aged 2-8 years. Inspired and expired end-tidal sevoflurane concentrations were held constant at 1.0 or 2.5 vol%, after which ECG and EEG were obtained for 15 minutes. Total power (TP), low-frequency power (LFP), high-frequency power (HFP), approximate entropy (ApEn), and Hurst exponent (H) were calculated from the ECG. The relationship between EEG and ECG indices at the two sevoflurane concentrations was measured by Pearson's correlation coefficient. RESULTS: As anesthesia deepened, ApEn, H of ECG and beta wave decreased and those of delta and theta increased in 4 channels. In FP2, changes of beta and theta wave were negatively correlated with ApEn and H of ECG (P < 0.05), and changes of delta wave was positively correlated with ApEn (P < 0.05) and H (P < 0.01). In F8, changes of beta and theta wave were negatively correlated with ApEn (P < 0.05) and only theta wave was negatively correlated with H (P < 0.05). In C4, change of delta wave was positively correlated with ApEn (P < 0.001) and H (P < 0.05). CONCLUSIONS: EEG and ECG indices are correlated during sevoflurane anesthesia in children, and ECG-derived indices could possibly be used to monitor depth of anesthesia.

Effect of a ketogenic diet on EEG: analysis of sample entropy.

Although ketogenic diet (KD) is an effective alternative therapy for controlling intractable seizures, the anticonvulsant mechanism still remains unclear. Sample entropy (SampEn) provides a generalized measure of regularity in time-series data. To investigate the potential anticonvulsive mechanism of a KD, we analyzed the SampEn of electroencephalography (EEG) data in patients with intractable pediatric epilepsy before and after treatment with a KD. Seventeen pediatric patients with epilepsy who were treated with KD were enrolled in present study. Patients were classified as good responder and poor responder according to therapeutic responsiveness on KD. Thirty segments of 30-s epochs were selected before and after KD from each patient which were subject to SampEn. The KD increased the SampEn in the whole patient population; the SampEn increased significantly in all electrodes in the good responders, but the change in SampEn varied according to the electrode in the poor responders. Before the KD, the good responders had significantly lower SampEn values than the poor responders, but after the KD, SampEn values were higher in the good responders than in the poor responders. KD may have an anticonvulsive effect by decreasing the regularity of the EEG dynamics.

Source localization of triphasic waves: implications for the pathophysiological mechanism.

To investigate the current source location from the electroencephalograms (EEGs) of 12 patients who showed typical triphasic waves attributable to various causes, using the combination of a dipole source model and a distributed source model. The triphasic waves were explained by a single main dipole in 10 of the 12 patients, and 2 patients had two dipoles responsible for the triphasic waves. All the main dipoles had a radial orientation with respect to the frontal pole. The current density of the triphasic waves was distributed mainly in the bilateral medial frontal regions along the cingulate cortices. These findings suggest that current sources located in the medial frontal area are crucial for generating triphasic waves. The source localization may be useful for elucidating the pathophysiologic mechanism of generalized non-epileptic EEG activities, such as triphasic waves.

Identification of patients with childhood moyamoya diseases showing temporary hypertension after anesthesia by preoperative multifractal Hurst analysis of heart rate variability.

OBJECTIVE: This study was performed to determine whether the preoperative multifractal Hurst analysis of heart rate variability might identify and characterize childhood patients with moyamoya disease (MMD) who showed temporary postoperative hypertension. METHODS: We studied 59 childhood patients with MMD. Thirty were classified as hypertensive group when the mean arterial pressure in the postoperative recovery room was 120% or greater than that during the preoperative period and 29 were classified as normotensive group. The 2 groups were compared with respect to preoperative indices of heart rate variability including frequency-domain measures, approximate entropy, and very short-term multifractal Hurst exponents of RR intervals (RRI). Using preoperative indices that showed significant differences, discriminant analysis was performed to identify postoperative hypertensive patients. RESULTS: Only exponents of the order > or =3 (H3alpha, H4alpha, and H5alpha) were significantly lower in the hypertensive group than in the normotensive group. Frequency-domain measures, approximate entropy, and the exponents of the order < or =2 were not significantly different in the 2 groups. Discriminant analysis using all of the three exponents correctly identified 27/30 (90%) of the postoperative hypertensive patients. CONCLUSIONS: Preoperative very short-term multifractal Hurst analysis of RRI variability identified 90% of childhood MMD patients who developed postoperative hypertension. The preoperative characteristic of RRI variability was the reduced smoothness at the 8-second-long, local RRI regions within which a very large change of RRI occurs.

Different etiologies of intrauterine growth restriction and different consistencies in the occurrence of abnormal local nonstationarity of fetal heart rate.

Fetuses with intrauterine growth restriction (IUGR) can be programmed in utero to develop hypertension in adult life. The etiology of IUGR in human fetuses is not uniform. The present study demonstrated that different etiologies of growth restriction, idiopathic cause, and pregnancy-induced hypertension, produce different consistencies in the occurrence of an abnormal local very-short-term nonstationarity of heart rate during intrauterine period. Whether the consistent abnormality that was found in the growth-restricted fetuses associated with pregnancy-induced hypertension is linked to the different risk of later hypertension requires future studies.

Instability and frequency-domain variability of heart rates in fetuses with or without growth restriction affected by severe preeclampsia.

This study investigated how the instability and frequency-domain variability in heart rates differ between fetuses affected only by severe preeclampsia and fetuses affected by both severe preeclampsia and growth restriction. From their antepartum fetal heart rates and those of control fetuses, the very short-term intermittency (C1alpha) and the spectral powers were calculated to evaluate the instability and frequency-domain variability, respectively. The fetuses affected only by severe preeclampsia showed abnormally high C1alpha and low- and high-frequency power. The fetuses affected by severe preeclampsia and growth restriction showed even higher C1alpha than that of the fetuses affected by severe preeclampsia and abnormally reduced low-frequency power. Conclusively, when compared to the heart rates of fetuses affected only by severe preeclampsia, the heart rates of fetuses affected by severe preeclampsia and growth restriction showed a greater abnormal instability and an abnormally reduced variability at low-frequency range.

Fourier transformation of arterial Doppler waveforms of the lower extremity.

PURPOSE: Although it is well known that the normal, triphasic pulsatile arterial Doppler waveform changes in shape as flow is impaired, interpretation of the waveform has largely been subjective. We aimed to describe the Doppler waveforms of the lower extremity objectively using Fourier transformation. METHODS: Sixty-eight zero-crossing detector arterial recordings from 25 lower extremities were grouped as follows: group 1, no ischemic symptoms with an ankle-brachial index (ABI) > 0.9 (n = 17, 8 limbs); group 2, no ischemic symptoms with ABI < 0.9 (n = 18, 5 limbs); group 3, symptoms of claudication (n = 19, 7 limbs); group 4, rest pain or tissue loss (n = 14, 5 limbs). The waveforms were Fourier transformed and their amplitudes and phases were compared up to the third harmonic (H3). RESULTS: Amplitudes of both the fundamental (H1) and second harmonic (H2) were predominant in group 1. In contrast, amplitudes of the H2 and H3 decreased with altered flow (p < 0.0001 for group 1 versus others). The phases of the H1 and H2 were delayed with altered flow (p < 0.05 for group 1 versus others). Phases of the H1 were different between group 2 and 4 (p < 0.05). The difference of phase between the H3 and H1 was shortened with altered flow (p < 0.05 for group 1 or 2 versus group 4). Multivariate analysis revealed that the relative amplitudes of the H2 and H3, the phases of the H1 and H2, and the relative phase of the H3 were significant discriminators among the groups. CONCLUSION: Abnormal waveforms could be characterized by the predominant amplitude of the H1, phase delay of the H1 and H2, and shortening of the relative phase of the H3. These parameters may be useful in the evaluation of Doppler waveforms in patients with peripheral arterial disease.

A consistent abnormality in the average local smoothness of fetal heart rate in growth-restricted fetuses affected by severe pre-eclampsia.

An abnormality in cardiovascular regulation during the prenatal period has been suggested to be the pathophysiological link between fetal growth restriction and adult hypertension. The purpose of this study was to determine how consistently abnormal the local smoothness of the very-short-term heart rate is in growth-restricted fetuses associated with severe pre-eclamptic pregnancy. Multifractal Hurst analysis on the structure function of heart rate was performed in control fetuses (n =150), in fetuses affected by severe pre-eclampsia and not showing growth restriction (n =66) and in fetuses affected by severe pre-eclampsia and showing growth restriction (n =58). The very-short-term (< or =15 heart beats) generalized Hurst exponents of the order of -5 to 5 in three groups were compared. Each exponent quantifies an average local heart rate smoothness at 15-successive-heart rate sites, which were specified by the magnitude of the heart rate variation within the sites determined by and positively correlated with the order of the exponent. This means that the fetal heart rates within the sites of q > or =2 have a large fetal heart rate (FHR) variation, and those within the sites of q < or =-2 have a small FHR variation. In the fetuses affected by severe pre-eclampsia and not showing growth restriction, only values of the exponents of the order > or =2 were abnormally lower. In the fetuses affected by severe pre-eclampsia and showing growth restriction, the values of the exponents of all orders were abnormally lower. In conclusion, the local smoothness of heart rate is consistently abnormal regardless of the magnitude of heart rate variation within a very-short-term period in growth-restricted fetuses affected by severe pre-eclampsia.

A very-short-term intermittency of fetal heart rates and developmental milestone.

We noticed that fetal heart rates (FHR) of immature fetuses intermittently showed unstable sudden and brief falls below baseline FHR that occur over a few or several heartbeats. The frightening falls do not occur in mature fetuses. In nonlinear dynamics, the degree of such abrupt falls in time series is quantified as intermittency. We aimed to investigate the nature and maturational changes of intermittency of the FHR in normal fetuses and to present the intermittency values of normal fetuses according to gestational weeks. FHR data of 450 normal fetuses between 23 and 40 wk of gestation were studied. We performed multifractal analysis and highlighted a very-short-term intermittency (C1alpha, 4

Increased intermittency and decreased nonstationarity of heart rates during the daytime in patients with neurocardiogenic syncope.

INTRODUCTION: During head-up tilt (HUT) test, patients with neurocardiogenic syncope show a sudden severe decrease in heart rate at the beginning of their induced syncopal attacks (termed intermittency). They also exhibit slow and progressive increases in their mean heart rates long before the induced syncopal attacks (termed nonstationarity). The aim of this study was to test our hypothesis that during daily activity, although not as prominently as during HUT test, patients show different degrees of intermittency and nonstationarity compared to healthy persons. METHOD AND RESULTS: Thirty patients with a positive HUT test and 30 healthy controls without a history of syncope were studied. The RR intervals of their 24-hour ambulatory ECGs were analyzed. To quantify the intermittency (C1) and nonstationarity (H1) behavior, multifractal analysis was performed using Mexican hat and Haar wavelet function, respectively. In the syncope group, C1 and H1 were significantly higher at 6 A.M.-6 P.M. and lower at 6 A.M.-midnight, respectively. However, the values were not different at midnight-6 A.M. The significant night-day circadian change shown in the control group was lost in C1 and diminished in H1. CONCLUSION: Patients with neurocardiogenic syncope show increased intermittency and decreased nonstationarity of heart rates in the daytime during daily activity, and abnormal night-day circadian changes of the intermittency and nonstationarity. These findings may be useful in the early identification of patients with neurocardiogenic syncope and in the investigation of abnormalities in heart rate regulating mechanisms.