Neurophysiological investigations of hepatic encephalopathy: ISHEN practice guidelines

Neurology Clinique Edith Cavell, Bruxelles, Belgium.
Liver international: official journal of the International Association for the Study of the Liver (Impact Factor: 4.85). 07/2009; 29(6):789-96. DOI: 10.1111/j.1478-3231.2009.02030.x
Source: PubMed


By studying neuronal activity through neuronal electrogenesis, neurophysiological investigations provide a functional assessment of the nervous system and, therefore, has been used for quantitative assessment and follow-up of hepatic encephalopathy (HE). The different clinical neurophysiological approaches can be classified depending on the function to explore and their sensitivity to HE. The reliable techniques are those that reflect cortical function, i.e., cognitive-evoked potentials (EPs) (P300 paradigm), electroencephalogram (EEG), visual EPs (latency>100 ms) and somatosensory EPs (SEPs) (latency between 25 and 100 ms). Short-latency EPs (brainstem acoustic EPs, SEPs of a latency<25 ms) are in principle insensitive to HE, but can disclose brainstem conduction deficits due to oedema. SEPs and motor EPs can disclose myelopathies. Because of its parallelism to the clinical examination, clinical neurophysiology can complement the neurological examination: (i) to provide evidence of HE in patients who have normal consciousness; (ii) to rule out, at least under some conditions, disturbances of consciousness due to other causes (e.g. drug-induced disturbances, non-convulsive status epilepticus) with the reservation that the mildest degrees of encephalopathy might be associated with an EEG pattern similar to that induced by drugs; and (iii) to demonstrate the worsening or, conversely improvement, of HE in the follow-up period.

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Available from: Oriano Mecarelli, Oct 13, 2014
    • "Triphasic waves appear quite late in the progression of the disease, i.e. when the encephalopathy is quite severe with marked hyperammonemia, often responsible for stupor, whereas coma is most often associated with slowing (delta waves) or even a discontinuous EEG trace [75]. Focal abnormalities can be observed in the absence of underlying lesions [64]. In 15% of cases, one can find some focal spikes, or diffuse spike-and-waves [51]. "
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    ABSTRACT: Electroencephalogram (EEG) recording in the laboratory lasts at least 20minutes and uses 19 active electrodes. It includes rest periods, stimulation procedures, a 3-mn hyperventilation period and intermittent photic stimulation (IPS). Recorded at the bedside, the EEG uses at least eight electrodes; the stimulation procedures, duration of the EEG and need to repeat the examination depend on the indication. Simultaneous video recording is recommended. The EEG report describes the basic rhythm, its reactivity and pathological activities, whether epileptic or not, and their organization. The synthetic conclusion interprets the results while taking into account the clinical context and contributes, if possible, diagnostic and/or therapeutic help in patient management. EEG performed as soon as possible after a seizure is essential for the diagnosis and initial management of epilepsy. It is helpful to characterize the epileptic syndrome in order to initiate optimal treatment. EEG is also useful in managing the withdrawal of antiepileptic drugs. EEG is also extremely useful in case of impaired consciousness, confusional state or even acute or subacute cognitive disorders. It is the only available tool able to validate the diagnosis of non-convulsive status epilepticus presenting with confusional state. EEG helps in the diagnosis of toxic or metabolic encephalopathy and can assess its severity, especially in hepatic encephalopathy. Except in rare exceptions, EEG is not routinely indicated for the evaluation of typical vasovagal syncope, headaches, dizziness, typical transient global amnesia and transient ischemic attack. EEG is irreplaceable in the diagnosis and management of certain severe and frequent pathologies involving the cerebral cortex. Copyright © 2015. Published by Elsevier SAS.
    No preview · Article · Jan 2015 · Neurophysiologie Clinique/Clinical Neurophysiology
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    • "This model has been well established relative to clinical status, liver function, blood–brain barrier integrity, and brain edema development (Zimmermann et al. 1989; Hilgier et al. 1996; Rama Rao et al. 2010b), and is the most widely used animal model of AHE. This model was recognized by International Society for Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) as a highly suitable animal model of AHE since the pathophysiological, biochemical and clinical findings are very similar to those in humans with AHE (Butterworth et al. 2009; Guerit et al. 2009). "
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    ABSTRACT: Astrocyte swelling and the subsequent increase in intracranial pressure and brain herniation are major clinical consequences in patients with acute hepatic encephalopathy. We recently reported that conditioned media from brain endothelial cells (ECs) exposed to ammonia, a mixture of cytokines (CKs) or lipopolysaccharide (LPS), when added to astrocytes caused cell swelling. In this study, we investigated the possibility that ammonia and inflammatory agents activate the toll-like receptor 4 (TLR4) in ECs, resulting in the release of factors that ultimately cause astrocyte swelling. We found a significant increase in TLR4 protein expression when ECs were exposed to ammonia, CKs or LPS alone, while exposure of ECs to a combination of these agents potentiate such effects. In addition, astrocytes exposed to conditioned media from TLR4-silenced ECs that were treated with ammonia, CKs or LPS, resulted in a significant reduction in astrocyte swelling. TLR4 protein up-regulation was also detected in rat brain ECs after treatment with the liver toxin thioacetamide, and that thioacetamide-treated TLR4 knock-out mice exhibited a reduction in brain edema. These studies strongly suggest that ECs significantly contribute to the astrocyte swelling/brain edema in acute hepatic encephalopathy, likely as a consequence of increased TLR4 protein expression by blood-borne noxious agents. Ammonia and inflammatory agents, such as lipopolysaccharide (LPS) or cytokines (CKs), activate the toll-like receptor 4 (TLR4) in endothelial cells (ECs) ultimately resulting in astrocyte swelling. TLR4 protein upregulation was detected in rat brain ECs in acute hepatic encephalopathy (AHE), whereas TLR4 knock-out mice exhibited a reduction in brain edema after AHE. These studies suggest that ECs significantly contribute to the astrocyte swelling/brain edema in AHE.
    Full-text · Article · Nov 2013 · Journal of Neurochemistry
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    • "In several studies spectral analysis of EEG has been proven to be a valuable, sensitive and observer –independent method to detect minimal HE [19,26], therefore it can be used as a reference tool and we applied it in our study as well. However the EEG detects cortical neuronal activity and may not ideally reflect a wide variety of neurophysiological events seen in HE [24]. Moreover it is not broadly implemented in a daily practice because of its limited availability and the need of an experienced personnel to appropriate interpretation of the obtained electroencephalograms. "
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    ABSTRACT: Mini-Mental State Examination (MMSE) is one of the most commonly used methods in the assessment of cognitive mental status. MMSE has been used in hepatology but its usefulness in the evaluation of hepatic encephalopathy (HE) has never been properly assessed. The aim of the study was to investigate the value of MMSE in detection of HE in patients with cirrhosis. One hundred and one consecutive patients with liver cirrhosis underwent neurological examination, MMSE and electroencephalography (EEG). Spectral analysis of EEG was done with calculation of mean dominant frequency (MDF) and relative power of delta, theta, alpha and beta rhythms. Minimal HE was diagnosed in patients with normal neurological status and alterations in spectral EEG. Statistical analysis included Fisher's exact and Anova analysis. Categorical data were compared using Levene's test for equality of variances. Correlation-coefficient analysis was performed by the Pearson's r or Z-test, as needed. Tests performance was assessed by the calculating the area under the ROC curve (AUC) and evaluating its difference from reference area (AUC=0.5). A p value <0.05 was considered statistically significant. Overt HE was identified in 49 (48.5%) and minimal HE in 22 (21.8%) patients. Although there were significant correlations between both severity of liver disease (Child-Pugh classification), overt HE (West-Haven criteria) and various MMSE items, MDF showed no correlation with any of MMSE items as well as MMSE summary score. MMSE (score and items) did not discriminate patients without HE and minimal HE. The only significant differences between patients without HE and with overt HE were seen in respect of MMSE score (p<0.02), orientation to place (p<0.003), repetition (p<0.01) and complex commands-understanding (p<0.02). Test performance analysis has shown that MMSE has no value as a prediction method in determining minimal HE and in respect of overt HE has a sensitivity of 63% and specificity of 52% by a cut-off level at 27.5 points to diagnose overt HE. In conclusion, although MMSE score and single items are altered in patients with overt HE, MMSE has no value in the assessment of minimal HE. Because MMSE could be impaired in several cognitive dysfunctions, more specific test should be used for measuring HE.
    Full-text · Article · Jul 2013 · BMC Gastroenterology
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