Application status of generalized periodic discharges in continuous electroencephalography monitoring in hypoxic-ischemic encephalopathy / 中华神经科杂志

In the electroencephalography (EEG) monitoring of patients with hypoxic-ischemic encephalopathy, generalized periodic discharges are often monitored abnormal waveforms. When there are some features of generalized periodic discharges (e.g., frequency≥1.5 Hz or plus), it indicates that the patient is at high risk for seizures or has a poor prognosis. Compared with conventional EEG, the time of continuous EEG monitoring is longer, so the detection rate of these waveforms is higher. At present, scholars at home and abroad have studied these waveforms, but there is controversy about the significance of these waveforms. In this paper, the definition and characteristics of these waveforms and their significance in determining prognosis and guiding treatment in patients with hypoxic-ischemic encephalopathy are reviewed.

Generalized periodic discharges with triphasic morphology

Generalized periodic discharges (GPDs) with triphasic morphology are an electroencephalographic (EEG) pattern traditionally associated with encephalopathy and coma, although they have been observed in a wide array of neurological disorders. The clinical significance of these waveforms and their relationship to seizures and prognosis has been debated, and differentiation between interictal patterns, patterns associated with seizures, and patterns representing nonconvulsive status epilepticus can at times be a challenge. The most established literature suggests that GPDs, including those with triphasic morphology, are associated with the development of electrographic seizures, but that in the absence of clinical information, distinguishing waveforms based on morphology alone may not be clinically useful. Recent work has advocated for a more proactive approach in evaluating GPDs with triphasic morphology. Further studies of nonsedating antiseizure drugs in patients with GPDs with triphasic morphology that incorporate continuous EEG monitoring will be useful in tailoring therapy to optimize long-term clinical outcomes and recovery.

Dipole Source Localization of Periodic Sharp Wave Complexes in Creutzfeldt-Jakob Disease

BACKGROUND: Patients with Creutzfeldt-Jakob disease (CJD) show periodic sharp wave complexes (PSWCs) on electroencephalography (EEG) during the course of their illness. However, the source location of PSWCs and the pathophysiological mechanism remains unclear. METHODS: Ten patients with sporadic CJD who showed typical PSWCs on EEG underwent brain magnetic resonance imaging (MRI) and positron emission tomography (PET, n=8) or single-photon emission computed tomography (SPECT, n=2) scans. A 30-second epoch from the EEG was selected for analysis. The recording was separated blindly using independent component analysis. The separate independent components were subjected to dipole source localization using a single dipole model. The source locations were compared with neuroimaging findings in each patient. RESULTS: Two to three independent components responsible for the PSWCs seen in CJD were identified. The EEG recording reconstructed from the selected independent components accounted for about 70% of the variance in the original recording. All but one patient had dipole sources localized in both cortical and subcortical areas. One patient had only subcortical dipole sources in both caudate nuclei. The cortical locations included the cingulate, insula, frontal, temporal, and occipital areas. The subcortical sources were located in the striate, thalamic, and subthalamic nuclei. All the dipole sources were localized within lesions seen as neuroimaging abnormalities. CONCLUSIONS: These results suggest that a subcortical mechanism, in addition to cortical structures, is involved in producing the generalized periodic discharges in CJD.