The significance of frontal intermittent rhythmic delta activity in children

Review of Noninvasive Neuromonitoring Modalities in Children II: EEG, qEEG

Critically ill children with acute neurologic dysfunction are at risk for a variety of complications that can be detected by noninvasive bedside neuromonitoring. Continuous electroencephalography (cEEG) is the most widely available and utilized form of neuromonitoring in the pediatric intensive care unit. In this article, we review the role of cEEG and the emerging role of quantitative EEG (qEEG) in this patient population. cEEG has long been established as the gold standard for detecting seizures in critically ill children and assessing treatment response, and its role in background assessment and neuroprognostication after brain injury is also discussed. We explore the emerging utility of both cEEG and qEEG as biomarkers of degree of cerebral dysfunction after specific injuries and their ability to detect both neurologic deterioration and improvement.

Clinical correlates and electroencephalographic features of FIRDA in a tertiary center

OBJECTIVES

We aimed to explore the diagnostic value, clinical correlates and electroencephalographic features of FIRDA (Frontal intermittent rhythmic delta activity).

MATERIALS AND METHODS

We retrospectively reviewed reports from EEG studies done in adults at our tertiary center between January 2015 and May 2018. For cases demonstrating FIRDA, medical files were reviewed and each case was given a diagnostic category. EEG recordings were reviewed and electrophysiologic data were extracted including FIRDA characteristics (frequency, location, duration, and symmetry). Then, a statistical analysis was done to evaluate the relationship between the diagnostic categories and EEG variables.

RESULTS

Ninety-four cases of FIRDA were found, with a frequency of 1.6% among inpatients. EEG recordings were available for review in 84 cases. FIRDA was asymmetric in 43 of these cases (49%), usually more prominent on the left (36/43, 84%). The diagnostic category groups included epilepsy (n = 39, 41%), other central nervous system (CNS) disease (n = 33, 35%), and systemic illness (n = 22, 23%). A significant difference in FIRDA location was found, as patients with epilepsy or other CNS disease, had a significantly higher probability for the delta activity to involve the temporal areas (frontotemporal location in 27/64 in these groups compared with 3/20 in the systemic illness group, P-value = .033).

CONCLUSIONS

This study provides insights to the diagnosis underlying FIRDA, especially the high rate of epilepsy patients, and calls for further neurologic investigation of cases in which FIRDA involves the temporal areas since most of these cases were due to epilepsy or other CNS disease and not a systemic illness.

Prognosis of Periodic and Rhythmic Patterns in Adult and Pediatric Populations

Although electrographic seizures are known to have an outcome on clinical prognosis, the implications of periodic and rhythmic patterns are less clear. The outcomes of adults with these patterns have been reported and are often poor; however, the outcomes in pediatric populations are less well characterized and may be different than in the adult population, as the etiologies of periodic and rhythmic patterns may differ in children and adults. In adults, generalized periodic discharges are highly associated with toxic-metabolic disturbances, infection, and anoxic injury; 30% to 64% of patients have poor outcomes. By contrast, in pediatric patients, generalized periodic discharges are more commonly associated with refractory status epilepticus, with good outcomes in 50% to 77%. The underlying etiology of the periodic or rhythmic pattern has a large influence on overall morbidity and mortality.

Generalized and Lateralized Rhythmic Patterns

The relationship between generalized and lateralized rhythmic delta activity (RDA) and seizures is more ambiguous than the relationship between periodic discharges and seizures. Although frontally predominant generalized RDA is not associated with seizures, occipitally predominant RDA may be associated with the absence of seizures. Lateralized RDA seems to be more strongly associated with the presence of seizure activity. Appropriate recognition of generalized RDA and lateralized rhythmic delta activity may be confounded by benign etiologies of RDA, such as phi rhythm, slow alpha variant, subclinical rhythmic electrographic discharges of adults, or hyperventilation-induced high-amplitude rhythmic slowing. Angelman syndrome and NMDA-receptor antibody encephalitis can also produce morphologically distinct patterns of RDA.

Frontal intermittent rhythmic delta activity (FIRDA): is there a clinical significance in children and adolescents?

BACKGROUND

Frontal intermittent rhythmic delta activity (FIRDA) has been studied extensively in adults but published literature about its clinical correlates in children and adolescents is comparatively limited.

AIMS

This study was performed to find more evidence regarding the clinical significance of this electrographic pattern in the pediatric population.

METHODS

All electroencephalograms (EEGs) with FIRDA between 07/01/2006 and 12/31/2009 at our institution were identified. Clinical data were collected from charts of patients with FIRDA. A comparison group consisting of patients matched for age and location was assembled.

RESULTS

We identified 26 EEGs in 22 patients with this electrographic pattern from a total of 4627 EEGs. All 26 EEGs were performed because of a history of seizures or to rule out seizures. Two of the 22 patients did not have evaluable clinical data. Of the remaining, 18 had seizures. The events in 2 patients were determined to be non epileptic. Amongst the 18 patients with seizures, 10 had associated epileptiform discharges and only 2 were without epileptiform activity or localizing or lateralizing features. Two patients had brain tumor. Six patients had hydrocephalus. Three patients had encephalopathy due to anoxic, metabolic or infectious etiology. There was no statistically significant difference between the study and the comparison group for occurrence of brain tumor, hydrocephalus or encephalopathy.

CONCLUSIONS

FIRDA was uncommonly observed. It was associated with a variety of conditions and was not a specific marker of brain tumor, hydrocephalus or encephalopathy.