Clinical Features of Anterior Bradyrhythmia

Abstract

The present study examined the clinical significance of anterior bradyrhythmia (AB), which was described by Gibbs and Gibbs in 1964. The significance of AB in this report was indefinite because of unclear criteria and underdeveloped neuroradiology. We proposed a set of criteria of AB and reevaluated the clinical significance of the EEG pattern in correlation with the clinical and the computerized topography (CT) findings of the patients. The study material was 4019 EEGs examined in our laboratory during a 1-year period (1991). AB was recorded in 20 patients (0.5%), whose mean age was 69.8 years. Its incidence tended to increase with age. Sixteen patients [table: see text] (80%) had dementia and were classified into two types according to clinical features, as Binswanger (B)-type and Alzheimer (A)-type. B-type patients had gait disturbance, urinary incontinence, hemiparesis, and ECG abnormalities, and showed leuko-araiosis on CT. A-type patients had only dementia, and showed frontoparietal atrophy on CT. Delirium was found in 7 (35%) out of the 20 patients with AB, which may be an additional factor related to the appearance of the EEG pattern. B-type had lower frequency of AB than A-type. Both types showed slowed background activities; the alpha rhythm of B-type had lower frequency and tended to have higher amplitude than that of A-type. These EEG abnormalities may be indicative of subcortical or cortical dysfunction in the frontal areas.

Delta Activity at Sleep Onset and Cognitive Performance in Community-Dwelling Older Adults

“…9 Our study is the first to examine DASO based on nocturnal PSG, in which sleep is recorded in all participants, which may contribute to the greater prevalence than has been observed in previous studies of hospital EEGs. 5,6 Older age may be one important factor contributing significantly to the prevalence of DASO, 5,6,9 though our study did not find a statistically significant difference in age itself between DASO (+) versus DASO (−) group. Further, our participants were already selected based on age (older than 50 y) such that any effect of age and its association with DASO was possibly minimized.…”

“…[1][2][3][4] Frontal intermittent rhythmic delta activity (FIRDA) also has long been considered to be an abnormal variant in the EEGs of older adults, with prior work indicating a predominance of FIRDA among patients with dementia. 1,5,6 One complication in the literature is that in the transition to sleep in older adults, slow wave EEG activity may in fact reflect the intrusion of sleep related elements of the EEG into the waking state. As such, this type of slow wave EEG activity may reflect more the instability of wake sleep control that occurs with typical aging than a pathological process per se.…”

“…9,10 Previous reports consistently show a higher prevalence of this type of delta activity at sleep onset (DASO) in older adults. 5,6,9,10 Some investigators, e.g., Zurek et al 6 and Shiohama et al 5 , have found DASO to be associated with a higher prevalence of altered mental status based on accumulated EEG data. Katz and Horowitz, 9 however, found DASO in 16% of healthy older adults, suggesting it may represent a normal variant in this age range.…”

Longitudinal association of delta activity at sleep onset with cognitive and affective function in community‐dwelling older adults

“…For DASO, the clinical significance has been more controversial. Based on the data of patients evaluated in hospitals, correlation of DASO with brain dysfunction has been reported (Klass and Brenner, 1995;Shiohama et al, 1993;Stam, 2011;Zurek et al, 1985). Although these studies are not representative of healthy community-dwelling older adults, the fact that DASO has been reported repeatedly in older adults and in patients with structural lesions suggests that age-related brain changes could generate DASO (Gibbs and Gibbs, 1964;Klass and Brenner, 1995;Shiohama et al, 1993;Stam, 2011;Zurek et al, 1985).…”

“…We recently suggested that a distinction be made between delta activity at sleep onset (DASO) and slow wave activity that does not occur in the context of sleep onset (e.g., FIRDA) (Kawai et al, 2016). Although not termed DASO, previous reports consistently show a higher prevalence of this type of activity in older adults (Katz and Horowitz, 1983;Shiohama et al, 1993;Stam, 2011;Zurek et al, 1985), with some suggesting that it may represent normal variation among older adults because it occurs within a normal EEG background (Katz and Horowitz, 1983). DASO is characterized with the sequences of rhythmic, bilateral anterior slow activity in the delta range (mostly 1.5-2.5/s), duration varies between 2 and 10 s, and the voltage output may be considerably high (Katz and Horowitz, 1983;Stam, 2011).…”