Clinical Correlates of Frontal Intermittent Rhythmic Delta Activity in Children

Abstract

Frontal intermittent rhythmic delta activity is an electrographic pattern of unclear origin. Previously thought to correlate with deep midline and infratentorial pathology, rather, it appears to be associated with encephalopathy states in adults. The significance of frontal intermittent rhythmic delta activity in children has not been studied. We analyzed the electrographic characteristics and clinical associations of pediatric frontal intermittent rhythmic delta activity. This pattern was rarely detected, occurring in 20 of 1500 electroencephalographic (EEG) studies. Patients' ages ranged between 1.5 and 17 years. Most patients were awake and showed no signs of acute encephalopathy when frontal intermittent rhythmic delta activity occurred. Half of the children were cognitively impaired, and half had a history of epilepsy. Epileptiform activity was present in 55% of the EEG recordings. However, frontal intermittent rhythmic delta activity was part of the epileptiform discharge in only a minority of cases. The duration of frontal intermittent rhythmic delta activity bursts was longer in the mentally retarded group. Most patients did not have structural brain pathology. None had deep midline or infratentorial lesions. In conclusion, frontal intermittent rhythmic delta activity is rare in children, is not associated with acute encephalopathy or with deep midline or infratentorial lesions, and tends to occur during wakefulness. The electrographic characteristics of frontal intermittent rhythmic delta activity appear to differ between cognitively normal and mentally retarded children. ( J Child Neurol 2003;18:525—529).

Clinical Correlates of Occipital Intermittent Rhythmic Delta Activity (OIRDA) in Children

“…Frontal intermittent rhythmic delta activity is probably related to metabolic derangement, particularly in the presence of previous ischemic brain insults (Watemberg et al, 2002) in adults. In children, the significance of the frontal rhythm is still unclear, although it is not associated with acute encephalopathy and does not appear to be epileptic in nature (Watemberg et al, 2003).…”

“…Frontal intermittent rhythmic delta activity was initially attributed to deep or midline central nervous system lesions (Cobb, 1945). However, more recent studies have shown that it occurs during metabolic derangement in adults with previous brain insults (Watemberg et al, 2002) and as a rare finding of unclear significance (Watemberg et al, 2003) in children. Ipsilateral temporal intermittent rhythmic delta activity appears to be indicative of temporal epilepsy (Di Gennaro et al, 2003).…”

Non-epileptiform EEG abnormalities: an overview

“…Later studies, however, contended that such etiologic factors comprise only a small percentage of all conditions associated with FIRDA 15,17,[23][24][25][26][27][28] . These studies correlated the presence of FIRDA with a large number of disorders, including toxic-metabolic encephalopathies, early stages of coma, degenerative diseases and other conditions, affecting both cortical and subcortical structures 15,17,[23][24][25][26][27][28] . Schaul et al 15 studied 42 EEG records with FIRDA and found that this finding was non specific and had no correlation with increased intracranial pressure.…”

“…They concluded that FIRDA appears more common than previously reported, it is associated with a high range of intracranial lesions (especially if asymmetric) and encephalopathies and its occurrence should prompt investigation for these conditions. FIRDA is found in a number of conditions and its origin and pathophysiology are still unclear [23][24][25][26] . Additional diligent diagnostic investigation is recommended when FIRDA appears on an EEG of abnormal or otherwise normal subjects 27,28 .…”

Visual perception and frontal lobe in intellectual disabilities: a study with evoked potentials and neuropsychology

“…Subjects with ID have variable scores in perceptual and visual reasoning tests, which probably depend on the degree of brain function impairment and correlate with the N1a wave. On the other hand, it is known that people with ID, on average, have an abnormal frontal activity shown by increased power in the frontal slow waves irrespec-tive of the disability aetiology (Martín-Loeches et al 2001;Gasser et al 2003) and by outburst of frontal delta waves ( Watemberg et al 2003). Thatcher et al (2005) found that lower intelligence is associated with a lower frontal synchronisation as measured by coherence, with the posterior cortex.…”