Epilepsy Syndromes in Infancy
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Review Article Epilepsy Syndromes in Infancy Christian M. Korff, MD and Douglas R. Nordli, Jr., MD An increasing number of infantile epilepsy syndromes ognized as such by the majority, thanks to the recent have been recognized. However, a significant number developments in diagnostic techniques, such as video- of infants (children aged 1-24 months) do not fit in any electroencephalography, brain imaging, and cytogenetics. of the currently used subcategories. This article re- However, despite this remarkable progress, up to a quarter views the clinical presentation, electroencephalo- of infants with epilepsy do not fit in any of the proposed graphic findings, evolution, and management of the syndromes, or are classified into broad and unspecific following entities: early infantile epileptic encephalop- categories [8]. It is likely that additional entities are athy, early myoclonic epilepsy, infantile spasms/West waiting to be defined in this age group [1]. This article syndrome, severe myoclonic epilepsy of infancy, myo- reviews the clinical characteristics, electroencephalo- clonic-astatic epilepsy, generalized epilepsy with febrile graphic findings, evolution, and management of the infan- seizures plus, malignant migrating partial seizures of tile epileptic syndromes identified in infancy so far. Their infancy, hemiconvulsions-hemiplegia-epilepsy, benign main features are summarized in Table 1, and specific myoclonic epilepsy, and benign familial/nonfamilial treatment options for some of them are presented in Table infantile seizures. Issues related to their classification 2. Issues related to their classification are addressed at the are addressed. © 2006 by Elsevier Inc. All rights end of the review, and suggestions for further improve- reserved. ments in the classification of infantile epilepsies are proposed. Korff CM, Nordli Jr DR. Epilepsy syndromes in infancy. Pediatr Neurol 2006;34:253-263. Early Infantile Epileptic Encephalopathy With Suppression-Burst (Ohtahara Syndrome) Introduction Early infantile epileptic encephalopathy, or Ohtahara syndrome, is a severe neurologic condition first described An accurate diagnosis is considered the first and most in 1976 [9]. It is a rare entity, with a relative prevalence to critical step in the management of pediatric epilepsy [1,2]. West syndrome estimated at 1/40 or less [9]. It is charac- Delineating epilepsy syndromes serves that purpose. In terized by epileptic tonic spasms and a suppression-burst addition to improving communication between caregivers electroencephalogram (Fig 1). The suppression-burst pat- and establishing clear criteria for research studies, epilepsy tern is present in both waking and sleeping states, and syndromes can suggest underlying disease pathophysiol- appears in the first 3 months of life [9]. Partial tonic ogy, provide prognostic information to the families, and seizures can be observed, but myoclonic seizures are rare aid in the selection of appropriate diagnostic tests. Epi- [9]. Etiology is heterogeneous, and includes brain malfor- lepsy syndromes are the rational basis for selection of mations, migration disorders, mitochondrial diseases, and, appropriate antiepileptic drugs, surgical procedures, or rarely, inborn errors of metabolism, such as Leigh’s alternative treatment options [1,3,4]. disease or cytochrome oxidase deficiency [9,10]. The The epilepsy syndrome classification system adopted by seizures are usually intractable to antiepileptic medica- the International League Against Epilepsy in 1989 [5] has tions, and the developmental prognosis is uniformly poor been demonstrated to be reliable and applicable to children [9]. Surgery can be considered in those patients with [6,7]. Moreover, an increasing number of infantile (1-24 cortical malformations, such as cortical dysplasia or hemi- months) epileptic syndromes are being isolated and rec- megalencephaly. Ohtahara syndrome frequently evolves From the Epilepsy Center, Children’s Memorial Hospital, Chicago, Communications should be addressed to: Illinois. Dr. Nordli; Director, Epilepsy Center; Children’s Memorial Hospital; Box #29; 2300 Children’s Plaza; Chicago, IL 60614-3394. E-mail: [email protected] Received May 5, 2005; accepted July 27, 2005. © 2006 by Elsevier Inc. All rights reserved. Korff and Nordli: Epilepsy Syndromes in Infancy 253 doi:10.1016/j.pediatrneurol.2005.08.005 ● 0887-8994/06/$—see front matter Table 1. Main characteristics of the epileptic syndromes that present in infancy Syndrome Main Characteristics Early infantile epileptic encephalopathy First months; tonic seizures, spasms; suppression-burst; severe outcome Early myoclonic epilepsy First months; myoclonias, spasms; suppression-burst (sleep); severe outcome Infantile spasms First year; spasms; hypsarrhythmia; developmental delay Dravet syndrome First year; partial and generalized seizures, myoclonias; normal EEG at onset; later: generalized spike-waves and multifocal spikes; severe outcome Myoclonic astatic epilepsy First year; generalized myoclonic and astatic seizures; interictal parietal theta activity and bilateral spike-waves; variable outcome Malignant migrating partial seizures of infancy First year; continuous electrographic seizures, multiple areas of onset; severe outcome Generalized epilepsy with febrile seizures (ϩ) Variable seizure and developmental phenotype in addition to febrile seizures and afebrile generalized convulsions Hemiconvulsion-hemiplegia-epilepsy Prolonged unilateral febrile seizures; subsequent hemiparesis and partial epilepsy Benign myoclonic epilepsy First 3 years; myoclonic seizures; normal interictal EEG; normal development Benign familial/nonfamilial seizures First year; partial seizures; normal development into West syndrome, and for some, later, into Lennox- helped two patients with cryptogenic etiology, but was Gastaut syndrome [4,11,12]. Controversies exist as to ineffective in all others. Three patients had their seizure whether Ohtahara syndrome, West syndrome, and Len- activity controlled on zonisamide. This publication was nox-Gastaut syndrome are part of the same spectrum of particularly important because of the prognostic findings. the age-dependent epileptic encephalopathies, or whether On evolution, two groups with different prognoses were they each represent isolated syndromes with specific identified: one of them included seven patients, who characteristics [12,13]. evolved from Ohtahara syndrome to West syndrome and A recent report on 16 patients diagnosed with early later to Lennox-Gastaut syndrome, and all of these patients infantile epileptic encephalopathy indicated that the age at died; the second included patients with spike foci on first seizure ranged from 1 day to 3 months. There was no electroencephalogram: only one patient died, and seven sex predominance. All of the patients had tonic spasms, were seizure-free. Nevertheless, all patients in the second either in clusters or isolated. Hemiconvulsions, erratic group were physically and mentally severely handicapped focal motor seizures, and asymmetric tonic seizures were [14]. observed in one third to one half of the patients. General- ized clonic seizures were observed in one patient. The interictal electroencephalogram was characterized by 1- to Early Myoclonic Epilepsy/Encephalopathy 3-second bursts of high-voltage (150-350 V) slow waves This rare entity was termed “neonatal myoclonic en- and multifocal spikes, separated by suppression phases of cephalopathy” in its initial description [15]. It was further 2-5 seconds duration. This pattern was independent of the delineated and renamed “early myoclonic epileptic en- circadian rhythm. The spasms were accompanied by a cephalopathy” by Dalla Bernardina et al. in 1983 [16], and high-voltage slow wave followed by attenuation, some- “early myoclonic epilepsy” by Aicardi in 1985 [17]. Like times with low-voltage fast activity. The interictal sup- early infantile epileptic encephalopathy, it is characterized pression-burst pattern often disappeared during a cluster of by intractable seizures with onset during the first 3 months spasms. Partial seizures could precede or follow a cluster of life, suppression-burst interictal electroencephalogram, of spasms, but were also observed independently. Etiology and poor developmental prognosis [9]. Early myoclonic or associated conditions included two suspected cases of epilepsy is, however, distinguished from early infantile Aicardi syndrome, one case of hemimegalencephaly, one epileptic encephalopathy by its predominant clinical man- case of porencephaly, one case of hydrocephalus, one case ifestations, erratic myoclonias, and by the presence of a of lissencephaly, and four cases of nonspecific cerebral suppression-burst pattern mainly during sleep. Partial atrophy or dysgenesis. Adrenocorticotrophic hormone seizures are also observed, and include tonic spasms, isolated or in clusters, versive seizures, migrating clonic Table 2. Specific treatment options seizures, and asymmetric tonic seizures with occasional secondary generalization [9]. Patients with early myo- Epileptic Syndrome Treatment Options clonic epilepsy share most electroencephalographic char- Infantile spasms (West) Adrenocorticotrophic hormone, vigabatrin, acteristics with patients with early infantile epileptic en- ketogenic diet cephalopathy, although the duration of bursts and Dravet Stiripentol–valproic acid–clobazam, suppression epochs, and the length of burst-burst intervals topiramate Myoclonic astatic epilepsy Valproic acid,