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The alpha exceeded 100 µV in 9% and remained between 20 and 30 µV in 1%. In their study, the average alpha amplitude for children between 3 and 15 years was 56 µV, the amplitude of 90% of their children falling between 30 and 100 µV. The alpha amplitude in the study of Petersen and Eeg-Olofsson (1971) increased to a maximum at 6 to 9 years and then declined. Pampiglione (1972) reported amplitudes of 50 to 80 µV at age 2 years. Using the passive-eye-closure technique, Pampiglione (1972) found an amplitude of 50 to 100 µV at age 3 months, increasing to 100 to 200 µV at age 9 months.ĭuring passive eye closure, we have found considerable wave-to-wave amplitude variability in the first year of life, usually from 30 to 100 µV, with occasional waves reaching 200 µV in the latter part of the first year. Recording with the eyes open, Hagne (1968) found an amplitude of 10 to 20 µV in the first months of life, increasing to 20 to 40 µV at 6 to 12 months. The following data will help to assess whether abnormal amplitudes exist, particularly if they are too low, suggesting a focal or diffuse paucity of cortical activity. There is moderate intersubject variability of background amplitude. Thus, passive eye closure should be performed at times when complete alertness is assured. During drowsiness, the background activity can be 1 to 2 Hz less than that for wakefulness in children, this can persist for prolonged periods after sleep, even when the child appears alert. Drowsiness should be suspected if there is less than the usual quantity of muscle artifact for age. In estimating the background frequency, it is important to assure that the patient is not drowsy. The occipital rhythm may also be seen during crying, as this is often associated with eye closure. A low frequency filter (LFF) of 1 Hz might be helpful to decrease the quantity of movement artifact at such times. Gentle passive closure of the eyes can be maintained for a few seconds. The mean frequency at age 15 years is 10 Hz.īackground activity can be appreciated best by passive eye closure, as the background can be attenuated by eye opening as early as age 3 months.By age 2 years, a 7 to 8 Hz rhythm is usual this increases to 9 Hz by 7 years.a 6 to 7 Hz rhythm is characteristic from 9 to 18 months.There is no discernible dominant occipital activity until the age of 3 months, at which time a rhythm of 3 to 4 Hz can be seen. (1973), Pampiglione (1972), Petersen and Eeg-Olofsson (1971), and Samson-Dollfus and Goldberg (1979) have provided the frequency milestones outlined below. Studies by Dreyfus-Brisac (1975), Hagne et al. Hans Berger was the first to recognize that the frequency of background activity in childhood increases with age, (Gloor, 1969). Is there focal or diffuse excess delta activity for state?Ĭhildren Awake Recordings Background Activity.Are states (wakefulness, drowsiness, sleep, and arousal) easy to identify and do they contain normal features?.Are such features symmetrical or almost so?.Are normal phenomena present: alpha, mu, theta, V waves, spindles?.Is there any excessive focal or diffuse delta activity?.Are there any marked nonartifactual asymmetries beyond those normally accepted for certain waveforms?.For each state of alertness (wakefulness, drowsiness, sleep, and arousal), the electroencephalographer interpreting a child's recording should ask the following questions: However, to identify abnormalities in children's EEGs with confidence, it is first necessary to sharpen one's concept of normal features and their variations. Fortunately, most of the clinically significant EEG abnormalities in children are morphologically well defined. In addition, the superimposition of two or more waveforms often creates sharply contoured waves that can be mistaken for spikes. These factors create wider limits of normality than might be expected in adults. Moreover, infants and young children tend to become drowsy during the recording, and the electrographic alterations with drowsiness are greater than those with adults. Several waveforms, such as the initial response to hyperventilation and posterior slow rhythms of youth, may be normally asymmetrical.There may be considerable intersubject variability, possibly because of differences in maturation.The relative predominance of these wave types varies with age.The electroencephalograms (EEGs) of infants and children are normally characterized by a greater mixture of waveforms and frequencies than is found in adults.Occipital Sharply Contoured Waves and Delta.Positive Occipital Sharp Transients of Sleep (POSTS).