Secondary generalized epilepsy in childhood: EEG patterns and correlation with responsiveness to benzodiazepines or ACTH (preliminary note)

Early-Life Epilepsies and the Emerging Role of Genetic Testing

IMPORTANCE

Early-life epilepsies are often a consequence of numerous neurodevelopmental disorders, most of which are proving to have genetic origins. The role of genetic testing in the initial evaluation of these epilepsies is not established.

OBJECTIVE

To provide a contemporary account of the patterns of use and diagnostic yield of genetic testing for early-life epilepsies.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective cohort, children with newly diagnosed epilepsy with an onset at less than 3 years of age were recruited from March 1, 2012, to April 30, 2015, from 17 US pediatric hospitals and followed up for 1 year. Of 795 families approached, 775 agreed to participate. Clinical diagnosis of the etiology of epilepsy were characterized based on information available before genetic testing was performed. Added contributions of cytogenetic and gene sequencing investigations were determined.

EXPOSURES

Genetic diagnostic testing.

MAIN OUTCOMES AND MEASURES

Laboratory-confirmed pathogenic variant.

RESULTS

Of the 775 patients in the study (367 girls and 408 boys; median age of onset, 7.5 months [interquartile range, 4.2-16.5 months]), 95 (12.3%) had acquired brain injuries. Of the remaining 680 patients, 327 (48.1%) underwent various forms of genetic testing, which identified pathogenic variants in 132 of 327 children (40.4%; 95% CI, 37%-44%): 26 of 59 (44.1%) with karyotyping, 32 of 188 (17.0%) with microarrays, 31 of 114 (27.2%) with epilepsy panels, 11 of 33 (33.3%) with whole exomes, 4 of 20 (20.0%) with mitochondrial panels, and 28 of 94 (29.8%) with other tests. Forty-four variants were identified before initial epilepsy presentation. Apart from dysmorphic syndromes, pathogenic yields were highest for children with tuberous sclerosis complex (9 of 11 [81.8%]), metabolic diseases (11 of 14 [78.6%]), and brain malformations (20 of 61 [32.8%]). A total of 180 of 446 children (40.4%), whose etiology would have remained unknown without genetic testing, underwent some testing. Pathogenic variants were identified in 48 of 180 children (26.7%; 95% CI, 18%-34%). Diagnostic yields were greater than 15% regardless of delay, spasms, and young age. Yields were greater for epilepsy panels (28 of 96 [29.2%]; P < .001) and whole exomes (5 of 18 [27.8%]; P = .02) than for chromosomal microarray (8 of 101 [7.9%]).

CONCLUSIONS AND RELEVANCE

Genetic investigations, particularly broad sequencing methods, have high diagnostic yields in newly diagnosed early-life epilepsies regardless of key clinical features. Thorough genetic investigation emphasizing sequencing tests should be incorporated into the initial evaluation of newly presenting early-life epilepsies and not just reserved for those with severe presentations and poor outcomes.

Treatment of electrical status epilepticus by short diazepam (DZP) cycles after DZP rectal bolus test

The effects of rapid rectal diazepam introduction (DZP test) were investigated in 43 patients (age range 5 months-14 years) with electrical status epilepticus (ESE) undergoing EEG monitoring. A remission of the paroxysmal activity was obtained in 58% of cases, a negative response in 42%, particularly in hypsarrhythmic patterns. DZP test responders were aged over 12 months with organized paroxysmal EEG patterns, in particular with ESE during sleep (ESES). The patients who responded to the DZP test underwent short cycles (3-4 weeks) of relatively high dosage DZP (0.5-0.75 mg/kg). The response to treatment was positive in 64%, particularly in ESES conditions. 56% of responders to the DZP test but not to DZP therapy (five out of nine patients) presented a significant mental retardation; maturational factors were also likely to be present.

Rapid diazepam introduction (venous or rectal) in childhood epilepsy: taxonomic and therapeutic considerations

Rapid diazepam (DZP) introduction was investigated in 24 children with different types of cryptogenic or symptomatic generalized epilepsy and EEG epileptic "status" with EEG and pharmacologic monitoring. In 12 cases DZP was given intravenously and in another 12 by the rectal route. In general, intravenous administration proved more rapid and more effective as to high blood levels of DZP and the arrest of the paroxysmal activity. However, when the results were correlated to the different forms of paroxysmal EEG activity it was apparent that cases with a typical hypsarrhythmic EEG pattern under the age of 12 months and cases with unorganized paroxysmal activity over the age of 12 months are insensitive or only slightly sensitive to both intravenous and rectal introduction. A number of taxonomic and therapeutic considerations are presented.