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

A novel method: can stapedial acoustic reflex have a role in the diagnosis of minimal hepatic encephalopathy?

OBJECTIVE

Stapedial acoustic reflex is an easily accessible and applicable test which is also valuable for the clinical conditions which affect the various locations of the central nervous system. Searching the diagnostic value of stapedial acoustic reflex at minimal hepatic encephalopathy is the aim of this research.

METHODS

Diagnosis of minimal hepatic encephalopathy was conducted by mini-mental state and critical flickered frequency tests. Minimal hepatic encephalopathy diagnosed patients were established in the first group. Cirrhosis (without minimal hepatic encephalopathy or overt hepatic encephalopathy) diagnosed patients were created the control group. The stapedial acoustic reflex test was applied for minimal hepatic encephalopathy and the control group by audiologists in a soundproof room.

RESULTS

In total, 221 patients were screened and 97 patients meet the inclusion criterions. Out of 97 patients, 52 were the minimal hepatic encephalopathy patients and the remaining patients were the control group. Acoustic reflex tests battery includes the evaluation of two pathways called ipsilateral and contralateral. Ipsilateral way test results were found positive in all minimal hepatic encephalopathy patients and 95% positive in the control group. Contralateral acoustic reflex test results were found 36% positive in minimal hepatic encephalopathy patients and 95% positive in the control group, respectively. A comparison of ipsilateral and contralateral acoustic reflex test results was displayed a statistical significance.

CONCLUSION

Stapedial acoustic reflex test results of cirrhosis patients may cover additional parameters for the diagnosis of minimal hepatic encephalopathy.

Auditory and visual P300 event-related potentials to detect minimal hepatic encephalopathy

INTRODUCTION

Diagnosis of Minimal hepatic encephalopathy (MHE) requires psychometric tests, although new methods are needed since sensitivity, specificity, and accuracy are low. The P300 event-related potential (ERP) is obtained by auditory and visual stimuli, although only the auditory P300 has been used to detect MHE. We aimed to compare the diagnostic features of auditory and visual P300 to detect MHE.

MATERIALS AND METHODS

Sixty patients with liver cirrhosis and thirty-five healthy controls completed the Psychometric Hepatic Encephalopathy Score (PHES), the critical flicker frequency (CFF), auditory, and visual P300. MHE was diagnosed if PHES and CFF scores were abnormal.

RESULTS

Fifty-three cirrhotic patients (age 54.5±8.6 years) completed all tests. Abnormal scores were: PHES (49.1%), CFF (67.9%). The proportion of MHE was 21.4%. The area under the receiver operating ROC curves (AUROC) for auditory P300 was better than visual P300 for distinguishing MHE from controls (AUROC 0.792 vs 0.725; p<0.005 for both; accuracy 73.8%vs 70.2%; sensitivity 72.2% both; specificity 74.2 vs 69.7, respectively. Among cirrhotic patients, only auditory P300 was useful to detect MHE, AUROC 0.723 p<0.05; 77.4% accuracy; 61.1% sensitivity; and 81.8% specificity.

CONCLUSIONS

The auditory P300 sensitivity, specificity, and accuracy were similar to those of CFF. Our results showed that only auditory P300 is useful to differentiate patients with MHE. Although both modalities, auditory and visual, differentiated patients with cirrhosis from controls, we consider the visual P300 is not suitable for detecting MHE.

Pitch Processing Can Indicate Cognitive Alterations in Chronic Liver Disease: An fNIRS Study

Early detection and evaluation of cognitive alteration in chronic liver disease is important for predicting the subsequent development of hepatic encephalopathy. While visuomotor tasks have been rigorously employed for cognitive evaluation in chronic liver disease, there is a paucity of auditory processing task. Here we focused on auditory perception and examined behavioral and haemodynamic responses to a melodic contour identification task (CIT) to compare cognitive abilities in patients with chronic liver disease (CLD, N = 30) and healthy controls (N = 25). Further, we used support vector machines to examine the optimal combination of channels of functional near-infrared spectroscopy that can classify cognitive alterations in CLD. Behavioral findings showed that CIT performance was significantly worse in the patient group and CIT significantly correlated with neurocognitive evaluation (i.e., number connection test, digit span test). The findings indicated that CIT can measure auditory cognitive capacity and its difference existing between patient group and healthy controls. Additionally, optimal subsets classified the 16-dimensional haemodynamic data with 78.35% classification accuracy, yielding markers of cognitive alterations in the prefrontal regions (CH6, CH7, CH10, CH13, CH14, and CH16). The results confirmed the potential use of behavioral as well as haemodynamic responses to music perception as an alternative or supplementary method for evaluating cognitive alterations in chronic liver disease.

Towards a unified model of event-related potentials as phases of stimulus-to-response processing

This study demonstrates the utility of combining principles of connectionist theory with a sophisticated statistical approach, structural equation modeling (SEM), to better understand brain-behavior relationships in studies using event-related potentials (ERPs). The models show how sequential phases of neural processing measured by averaged ERP waveform components can successfully predict task behavior (response time; RT) while accounting for individual differences in maturation and sex. The models assume that all ERP measures are affected by individual differences in physical and mental state that inflate measurement error. ERP data were collected from 154 neurotypical children (7-13 years, M = 10.22, SD = 1.48; 74 males) performing a cued Go/No-Go task during two separate sessions. Using SEM, we show a latent variable path model with good fit (e.g., χ²(51) = 56.20, p = .25; RMSEA = .03; CFI = .99; SRMR = .06) yielding moderate-to-large predictive coefficients from N1 through the E-wave latent variables (N1 β = -.29 → P2 β = -.44 → N2 β = .28 → P3 β =.64→ E-wave), which in turn significantly predicted RT (β =.34, p = .02). Age significantly related to N1 and P3 latent variables as well as RT (β =.31, -.58, & -.40 respectively), and Sex significantly related to the E-wave latent variable and RT (β =.36 & 0.21 respectively). Additionally, the final model suggested that individual differences in emotional and physical state accounted for a significant proportion of variance in ERP measurements, and that individual states systematically varied across sessions (i.e., the variance was not just random noise). These findings suggest that modeling ERPs as a system of inter-related processes may be a more informative approach to examining brain-behavior relationships in neurotypical and clinical groups than traditional analysis techniques.

Minimal hepatic encephalopathy: A review

Minimal hepatic encephalopathy (MHE) is the earliest form of hepatic encephalopathy and can affect up to 80% of patients with liver cirrhosis. By definition, MHE is characterized by cognitive function impairment in the domains of attention, vigilance and integrative function, but obvious clinical manifestation are lacking. MHE has been shown to affect daily functioning, quality of life, driving and overall mortality. The diagnosis can be achieved through neuropsychological testing, recently developed computerized psychometric tests, such as the critical flicker frequency and the inhibitory control tests, as well as neurophysiological procedures. Event related potentials can reveal subtle changes in patients with normal neuropsychological performances. Spectral analysis of electroencephalography (EEG) and quantitative analysis of sleep EEG provide early markers of cerebral dysfunction in cirrhotic patients with MHE. Neuroimaging, in particular MRI, also increasingly reveals diffuse abnormalities in intrinsic brain activity and altered organization of functional connectivity networks. Medical treatment for MHE to date has been focused on reducing serum ammonia levels and includes non-absorbable disaccharides, probiotics or rifaximin. Liver transplantation may not reverse the cognitive deficits associated with MHE. We performed here an updated review on epidemiology, burden and quality of life, neuropsychological testing, neuroimaging, neurophysiology and therapy in subjects with MHE.