Three consecutive epilepsy syndromes in one child

A developmentally normal male presented from 2 to 8 years of age, with four prolonged nocturnal seizures (>15 min duration) characterized by impaired awareness, pallor, vomiting, and roving eye movements. Two events evolved into bilateral tonic–clonic seizures. Clobazam was initiated, but due to sedation, was replaced with Levetiracetam. Brain MRI was normal and EEG demonstrated bilateral centroparietal epileptiform discharges (EDs). A diagnosis of self-limited epilepsy with autonomic seizures (SeLEAS) was made. At 9 years of age, he developed brief daily staring episodes with eyelid fluttering, associated with 3 Hz generalized spike–wave (GSW) discharges, diagnostic of childhood absence epilepsy (CAE). In addition, he experienced migraine headaches, anxiety, and depression with suicidal thoughts, prompting close psychiatric follow-up. Valproic acid replaced Levetiracetam, resulting in seizure remission and minor improvement in anxiety and depression. From age 10–12 years, he experienced four nocturnal events consisting of drooling, dysarthria and unilateral, and right- or left-sided, facial twitching; one of which evolved into a bilateral tonic–clonic seizure. The EEG demonstrated bilateral centrotemporal EDs and a diagnosis of self-limited epilepsy with centrotemporal spikes (SeLECTS) was made (Figure 1). At 14 years of age, EEG demonstrated right occipital EDs. At 15 years of age, he is seizure-free for 3 years and weaning Valproic acid. EEG demonstrates right centrotemporal and occipital EDs. He undergoes regular counseling for anxiety and depression. SeLEAS, CAE, and SeLECTS are common childhood epilepsy syndromes. Although genetic factors contribute to the susceptibility of these syndromes, discordant monozygotic twin studies, suggest a genetic–environmental interaction exists, partly mediated by epigenetic factors.1 Despite similarities in age-dependent occurrence, unremarkable neuroimaging, and favorable outcomes of these three syndromes, they are distinct electroclinical entities that uncommonly coexist in individuals. There are few existing reports of patients with concurrent or successive combinations of two out of the three of the above-mentioned syndromes (Refer to Data S2). More commonly, there is an overlap of EEG features, without accompanying clinical features. For example, rolandic discharges, without clinical features, can appear in SeLEAS and CAE.2, 3 Our patient initially presented with SeLEAS, followed by CAE, which is notably rare. In a large prospective study, Caraballo identified only one case and it is postulated that a closer relationship exists between CAE and childhood occipital visual epilepsy.4, 5 After cessation of absence seizures, our patient developed SeLECTS, similar to other cases described in the literature.3, 6 Conversely, a 25-year single-center study described three individuals with SeLECTS which evolved to CAE.3 “CAE-like epilepsy” following SeLECTS can also be drug-related (Phenobarbital and Carbamazepine). Furthermore, these syndromes can occur simultaneously.3, 7 Notably, in patients with SeLECTS and CAE, differences in localized brain morphology are described, corroborating that these syndromes are distinct entities.8 A continuum between CAE and self-limited focal epilepsies may exist, with a possible common genetic factor expressed differently due to variable differential brain maturation. For example, 3-Hz occipital delta activity occurs in patients with CAE. Some have researched circuit mechanisms common to GSW and focal discharges. A mouse-model study demonstrated that the thalamocortical relay, integral for 3 Hz GSW discharges, is capable of producing highly organized and repetitive focal activity, such as rolandic discharges.9 Similar to our patient, others have reported SeLECTS arising after SeLEAS, but also concurrently.2 SeLEAS and SeLECTS are considered distinct entities within an age-dependent continuum.10 The electroclinical similarities potentially represent variable clinical phenotypes, similar to genetic generalized epilepsy with variable phenotypes in adolescents. In addition, centrotemporal and occipital spikes frequently occur together or on subsequent EEGs.2 These syndromes have similar variable neurophysiological expression and potentially similar cortical hyperexcitability, both demonstrating multifocal EDs propagating back-and-forth from posterior to anterior head regions. This was exemplified in our patient, with focal EDs having shifting predominance on serial EEGs. To our knowledge, coexistence of these three electroclinical syndromes in one individual is not previously described. It is unknown if this patient's unusual seizure evolution is related to genetic or environmental factors or coincidental. Seizure prognosis remains favorable; however, whether established psychiatric comorbidities including anxiety and depression, as observed in this patient, are amplified in patients with multiple consecutive syndromes requires further research, including genetic testing. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors declare that there is no conflict of interest. The patient provided consent for the case to be published. Data S1. Data S2. Appendix S1. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. The thalamocortical relay has a role in the generation of Which of the following EEG features occur in self-limited epilepsy with autonomic seizures (SeLEAS)? Which of the following is not a proposed explanation for the coexistence of childhood epilepsy syndromes in the same individual? Answers may be found in the supporting information.

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