From the Guidelines
EEG ripples are not directly addressed in the provided guideline evidence, which focuses on the use of electroencephalography in detecting changes in cortical cerebral activity in patients with hepatic encephalopathy, rather than specifically discussing high-frequency oscillations like ripples. When considering the use of EEG in clinical practice, it's essential to note that, according to the guideline evidence 1, EEG examination can detect changes in cortical cerebral activity across the spectrum of hepatic encephalopathy (HE) without patient cooperation or risk of a learning effect. However, the reliability of EEG analysis can be influenced by various factors, including accompanying metabolic disturbances and drugs. The guideline suggests that quantitative analysis, including background frequency with mean dominant frequency or spectral band analysis, may increase the reliability of EEG analysis 1. In the context of hepatic encephalopathy, EEG is considered a useful tool for assessing cerebral activity, but its interpretation requires consideration of the patient's history, current therapy, and effect on daily activities 1. For diagnosing minimal hepatic encephalopathy (MHE) or overt hepatic encephalopathy (CHE), the guideline recommends using at least two validated testing strategies, which may include EEG as a neurophysiological test 1. Given the information provided and focusing on morbidity, mortality, and quality of life, the use of EEG in clinical practice should be guided by its utility in assessing and managing conditions like hepatic encephalopathy, with careful consideration of its limitations and the need for specialized expertise and equipment. Key points to consider when using EEG in clinical practice include:
- The potential for EEG to detect changes in cortical cerebral activity without patient cooperation or risk of a learning effect 1.
- The importance of quantitative analysis to increase the reliability of EEG findings 1.
- The need for interpretation of EEG results in the context of the patient's overall clinical picture, including history, current therapy, and impact on daily activities 1.
From the Research
EEG Ripples
- EEG ripples are a type of brain activity that can be associated with both physiological and epileptic processes 2
- Ripples are characterized by high-frequency oscillations (80-250 Hz) and can be detected using intracranial electroencephalography (EEG) 2
- Epileptic ripples are often coupled to spikes, whereas physiologic ripples are not 2
- Distinguishing between physiologic and epileptic ripples is important for the diagnosis and treatment of epilepsy, as epileptic ripples can be a biomarker of seizure activity 2
Detection and Analysis of EEG Ripples
- EEG ripples can be detected using automated software, such as the Delphos software 2
- The analysis of EEG ripples can help identify the seizure-onset zone in patients with epilepsy 2
- The rates of spikes, ripples, and spike-ripples can be higher inside the seizure-onset zone 2
- Ripples can be more frequent in the eloquent neocortex than in other areas of the brain 2
Clinical Significance of EEG Ripples
- EEG ripples can be used as a biomarker of epileptic activity, but their value is limited by their association with physiological processes as well 2
- The distinction between physiologic and epileptic ripples can be important for the diagnosis and treatment of epilepsy 2
- EEG continues to be a useful ancillary test for the diagnosis of epilepsy, but its application requires proper understanding of its limitations and variability of testing results 3