The Electroencephalogram in

Abstract

EUROLOGICAL complications of congenital heart diseases have been well documented by Tyler and Clark.1,2 According to these authors, neurological deficits were detectable in 25.4%, blackout spells in 12.1% and convulsions in 5.8%. These investigations did not include electroencephalographic data.Thus far, a fair number of EEG studies has been carried out3-7; the principal EEG data are summarized in Table 1. In all of these studies, there was marked preponderance of abnormal EEG tracings. Nonspecific EEG findings (such as excessive slow activity) were most commonly reported with exception of the investigations of Shev and Robinson6 as well as Bek\l=e'\ny et al7 who noted the relatively high incidence of paroxysmal abnormalities (such as spikes).The scarcity of previous reports and the interesting aspects of the central nervous system (CNS) dependency on adequate oxygenation have been the incentive for this study. Materials and MethodsA total of 50 patients with unequivocal evidence of congenital heart disease were referred for electroencephalographic evaluation. The age of these patients ranged from 2 weeks to 16 years. The studies were carried out in the eight-year period from 1959 to 1966. The rea¬ son for EEG referral was the presence of CNS symptoms and signs. Patients with bacterial endocarditis and brain abscess were excluded from this study.Thirty-two patients underwent routine, sim¬ ple cardiological tests, but in 18 a more exten¬ sive cardiological workup was done including cardiac catheterization and venous angiocardi¬ ography.The EEG was obtained with eight-channel apparatuses. The International Electrode Sys¬ tem (10-20 system) was used; bipolar as well as referential recording techniques were utilized. No activation procedures were carried out. Sleep was obtained either naturally or induced by appropriate dosages of chloral hydrate or secobarbital.Follow-up EEG data were scanty and, in the majority of the patients, only one tracing was obtained.The material was broken down from several points of view. Cardiologically, a separation was made between cyanotic and noncyanotic conditions. The cardiological diagnosis and the distinction between cyanotic and noncyanotic conditions are shown in Table 2.From the electroencephalographic viewpoint, the patients were divided into those with nor¬ mal records (group 1), nonspecific abnormali¬ ties (group 2) and specific-paroxysmal abnor¬ malities (group 3). Furthermore, a distinction was made between focal and diffuse or general¬ ized-synchronous abnormalities. Nonspecific abnormalities consisted of exces¬ sive slow or, more seldom, fast activity. Minor sharp potentials, 14 and 6/sec positive spikes, deviant sleep patterns and asymmetries were also listed as nonspecific abnormalities.