1. Combination of Continuous Polymorphic Delta Activity and FIRDA; Massive Brain Edema with Central Herniation Syndrome. EEG of a 28-month-old girl with a history of biliary atresia, status post-Kasai operation at 2 months of age. She developed multiorgan failure caused by septicemia 1 week after the liver transplantation. She was in a comatose state requiring cardiorespiratory support and later intracranial pressure monitoring. Her cranial CT shows severely diffuse hypodensity in both hemispheres (double arrows) and thalamus (open arrow). These findings and clinical features were consistent with central herniation syndrome. EEG reveals a combination of nonreactive, continuously diffuse polymorphic delta activity (PDA) and frontal intermittent rhythmic delta activity (FIRDA), maximally expressed at Fz-Cz. Widespread continuous PDA occurs mostly in cortical deafferentiation caused by subcortical white matter lesions or, less commonly, in bilateral thalamic, hypothalamic, and upper mesencephalic lesions.76,78 IRDA (FIRDA or OIRDA) occurs in a wide variety of conditions involving both subcortical and cortical gray matter.82 A recent study showed that FIRDA may reflect a pathologic type of increased excitation of cortical and subcortical gray matter disease.83 The combination of IRDA (FIRDA or OIRDA) and continuous focal PDA is a classic sign of impending cerebral herniation from a focal structural lesion, but it is also seen in a wide variety of diffuse encephalopathies such as toxic or metabolic encephalopathy.36 The EEG, CT, and clinical features in this patient are consistent with impending central herniation syndrome caused by diffuse massive brain edema.
Source: Generalized Nonepileptiform Activity, Atlas of Pediatric EEG
Citation: Laoprasert P. Atlas of Pediatric EEG; 2011 Available at: Accessed: March 03, 2018
Copyright © 2018 McGraw-Hill Education. All rights reserved