A case of early infantile epileptic encephalopathy (EIEE) with anatomical cerebral asymmetry and myoclonus

Targeting the Mammalian Target of Rapamycin for Epileptic Encephalopathies and Malformations of Cortical Development

Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients. A recent explosion of genetic studies has linked mutations in various genes regulating the mTOR pathway to other cortical malformations, such as focal cortical dysplasia and hemimegalencephaly. Thus, mTOR inhibitors represent promising candidates as novel antiseizure and antiepileptogenic therapies for epilepsy associated with a spectrum of cortical malformations.

Paroxysmal nonepileptic motor phenomena in newborn

INTRODUCTION

Understanding the pathophysiological meaning of paroxysmal nonepileptic motor phenomena in newborns represents a challenge for the clinicians of the Neonatal Intensive Care Unit.

METHODS

This paper provides an extensive review of the most frequent paroxysmal nonepileptic motor phenomena in newborns, in order to improve the knowledge about this sub-topic of the neonatal pathology and to guide the diagnostic-therapeutic approach.

RESULTS

The correct identification of an epileptic form, among different motor phenomena, which may clinically mimic seizures, is essential for a correct management, avoiding overtreatment. However, it is likewise important to know and to be able to identify other rare neurological conditions, such as hyperekplexia, spinal muscular atrophy, acute bilirubin encephalopathy, that could make a first appearance with paroxysmal motor manifestations, needing specific diagnostic work-up and treatment.

CONCLUSIONS

These clinical events should not be underestimated because, even if many times they are physiological and age-related, sometimes they could be the visible signs of an underlying epileptic or nonepileptic neurological disease.

Early modified functional hemispherectomy in a young infant with Ohtahara syndrome and hemimegalencephaly

We report on the youngest infant treated with modified functional hemispherectomy at the age of 5 months for Ohtahara syndrome and hemimegalencephaly as underlying pathology, and we depict the favorable outcome regarding seizure control and psychomotor development. These results highlight the potential usefulness of early surgery in such conditions.

Epilepsy surgery for early infantile epileptic encephalopathy (ohtahara syndrome)

Early infantile epileptic encephalopathy or Ohtahara syndrome is the earliest form of the age-dependent epileptic encephalopathies. Its manifestations include tonic spasms, focal motor seizures, suppression burst pattern, pharmaco-resistance, and dismal prognosis. The purpose of this study was to evaluate the effectiveness of epilepsy surgery in selected infants. We identified 11 patients, 9 from the literature and 2 from our institution that fulfilled diagnostic criteria of Ohtahara syndrome and had undergone epilepsy surgery in infancy. Seven of the 11 infants have remained seizure free (Engel class IA) and four are reportedly having rare to infrequent seizures (Engel class IIB). All patients experienced "catch up" development. In contrast to Ohtahara's15 pharmacotherapy managed patients, who had a mortality rate of approximately fifty percent, and those that survived continued to have seizures and were severely impaired, the outcome of selected surgically managed patients is much more favorable.

Hemimegalencephaly accompanied by myoclonic status epilepticus

We describe a boy (aged 2 years and 7 months) with hemimegalencephaly who developed myoclonic status, which improved dramatically after total callosotomy. The patient experienced seizures beginning at age 2 days, at which time electroencephalography revealed a right unilateral burst suppression pattern, and cranial magnetic resonance imaging revealed an enlarged right hemisphere. At age 8 months, habitual seizures increased to more than daily frequency. At the same time, myoclonic status epilepticus appeared with frequent erratic, partial, massive myoclonic seizures and clouding of consciousness. These signs were accompanied by diffuse spike and spike-wave patterns on electroencephalography, indicating myoclonic status in nonprogressive encephalopathy. Total callosotomy performed at age 10 months resulted in the complete disappearance of myoclonic status and prominent decrease in habitual seizures. This description of hemimegalencephaly is the first, to our knowledge, in which total callosotomy alleviated myoclonic status epilepticus. Although the mechanism of myoclonic status epilepticus remains unknown, our results suggest that cortico-cortical pathways are involved in this type of myoclonic status.

Ohtahara syndrome with emphasis on recent genetic discovery

Ohtahara syndrome or Early Infantile Epileptic Encephalopathy (EIEE) with Suppression-Burst, is the most severe and the earliest developing age-related epileptic encephalopathy. Clinically, the syndrome is characterized by early onset tonic spasms associated with a severe and continuous pattern of burst activity. It is a debilitating and early progressive neurological disorder, resulting in intractable seizures and severe mental retardation. Specific mutations in at least four genes (whose protein products are essential in lower brain's neuronal and interneuronal functions, including mitochondrial respiratory chains have been identified in unrelated individuals with EIEE and include: (a) the ARX (aristaless-related) homeobox gene at Xp22.13 (EIEE-1 variant); (b) the CDKL5 (SYK9) gene at Xp22 (EIEE-2 variant); (c) the SLC25A22 (GC1) gene at 11p15.5 (EIEE-3 variant); and (d) the Stxbp1 (MUNC18-1) gene at 9q34-1 (EIEE-4 variant). A yet unresolved issue involves the relationship between early myoclonic encephalopathy (EME-ErbB4 mutations) versus the EIEE spectrum of disorders.

[Ohtahara syndrome--early infantile epileptic encephalopathy]

DEFINITION

Ohtahara syndrome (early infantile epileptic encephalopathy with suppression bursts), is the earliest developing form of epileptic encephalopathy. ETHIOLOGY: It considered to be a result of static structural developing brain damage.

CLINICAL PICTURE

Variable seizures develop mostly within the first 10 days of life, but may occur during the first hour after delivery. The most frequently observed seizure type are epileptic spasms, which may be either generalized and symmetrical or lateralized .The tonic spasms may occur in clusters or singly, while awake and during sleep alike. The duration of spasms is up to 10 seconds, and the interval between spasms within cluster ranges from 9 to 15 seconds. In one third of cases, other seizure types include partial motor seizures or hemiconvulsions The disorder takes a progressively deteriorating course with increasing frequency of seizures and severe retardation of psychomotor development.

DIAGNOSTIC WORKUP

In the initial stage of Ohtahara syndrome, interictal EEG shows a pattern of suppression-burst with high-voltage paroxysmal discharges separated by prolonged periods of nearly flat tracing that last for up to 18 seconds.

PROGNOSIS AND TREATMENT

Half of the reported children having Ohtahara syndrome die in infancy. Anticonvulsant helps little in controlling the seizures and halting the deterioration of psychomotor development. Severe psychomotor retardation is the rule. With time, the disorder may evolve into West syndrome or partial epilepsy. Psychomotor development may be slightly better if the infants do not develop West and later Lennox-Gastaut syndrome.

Are early myoclonic encephalopathy (EME) and the Ohtahara syndrome (EIEE) independent of each other?

BACKGROUND

Early myoclonic encephalopathy (EME) and the Ohtahara syndrome are currently listed as two separate syndromes in the classification of epilepsies. The most prominent differentiating points are the observations that patients with Ohtahara syndrome experience predominantly tonic seizures; their seizures evolve to infantile spasms and the prognosis is often worse than patients with EME.

SUMMARY POINTS

We performed a literature review of published cases. Although syndromes may have distinct courses, the differentiation early on may be impossible as both myoclonus and tonic seizures may coexist. There is also an overlap in the etiologies. Tonic seizures are considered a manifestation of brainstem dysfunction and it is possible that this is more prominent in Ohtahara syndrome. To date, there are 17 autopsy cases (12 presumed to be Ohtahara cases and 5 EME). Evidence of hindbrain pathology was present in all. Tonic seizures or tonic posturing was a feature of all cases. We suggest that the two syndromes may represent a continuum and that the prominence of tonic seizures in the Ohtahara syndrome may be an indication of brainstem dysfunction which may play an important role in the subsequent transition to infantile spasms.

Epileptic Encephalopathies in Early Infancy With Suppression-Burst

Early infantile epileptic encephalopathy with suppression-burst, or Ohtahara syndrome (OS), and early myoclonic encephalopathy (EME) are epileptic encephalopathies with onset of frequent seizures in the neonatal and early infancy period and with a characteristic EEG pattern, namely, suppression-burst, in which higher-voltage bursts of slow waves mixed with multifocal spikes alternate with isoelectric suppression phase. Their nosologic independence is now widely accepted, although some controversy initially occurred because of their common characteristics such as age of onset, EEG features, seizure intractability, and poor prognosis. Major differences between the two syndromes include (1) tonic spasms in OS versus partial seizures and erratic myoclonias in EME, (2) continuous suppression-burst pattern in both waking and sleeping states in OS versus this EEG pattern almost limited to sleep in EME, and (3) static structural brain damage in OS versus genetic or metabolic disorders in EME. The most important differentiating point is their evolutional pattern with age, which may reflect their pathophysiologic difference. Ohtahara syndrome evolves to West syndrome and further to Lennox-Gastaut syndrome with age, but EME demonstrates no unique evolution; namely, it continues as such for a long time or changes into partial epilepsy or severe epilepsy with multiple independent spike foci.

Early-infantile epileptic encephalopathy with suppression-bursts, Ohtahara syndrome; its overview referring to our 16 cases

Ohtahara syndrome (OS) is characterized by frequent tonic spasms, with or without clustering, of early onset within a few months of life, and a suppression-burst (S-B) pattern in electroencephalography (EEG). Tonic spasms occur in not only waking but also sleeping state in most cases. Partial seizures are observed in about one-third of cases. Brain imagings reveal structural abnormalities including malformations, notably asymmetric lesions in most cases.S-B pattern is persistently observed regardless of circadian cycle. Bursts of 1-3s duration alternate with nearly flat suppression phase of 2-5s at an approximately regular rate; 5-10s of burst-burst interval. Some asymmetry in S-B is noted in about two-thirds of cases. Ictal EEG of tonic spasms shows principally desynchronization with or without initial rapid activity. Tonic spasms appear concomitant with bursts. Characteristic age-dependent evolution from OS to West syndrome (WS) in many cases, and further from WS to Lennox-Gastaut syndrome (LGS) in some, proceed concomitantly with EEG transition from S-B to hypsarrhythmia at around age 3-6 months, and further from hypsarrhythmia to diffuse slow spike-waves at around age 1. Under the inclusive concept of the age-dependent epileptic encephalopathy, OS, WS, and LGS have common characteristics such as age preference, frequent minor generalized seizures, and continuous massive epileptic EEG abnormality. Mutual transition suggests the same pathophysiology among three syndromes and the age factor should be considered as the common denominator responsible for the manifestation of each of their own specific clinico-electrical features. Namely, these syndromes may be the age-specific epileptic reaction to various non-specific exogenous brain insults, acting at the specific developmental stages.

Neuropathology of early-infantile epileptic encephalopathy with suppression-bursts; comparison with those of early myoclonic encephalopathy and West syndrome

For the critical lesions and pathomechanism of early-infantile epileptic encephalopathy (EIEE) with suppression-bursts, we investigated the brains of EIEE, early myoclonic encephalopathy (EME), and West syndrome (WS) patients using immunohistochemical technique and neuropathological examination. We could compare with the results of these diseases. The EIEE patients had the most severe lesions, which were in the putamen, thalamus, hippocampus as well as the tegmentum of the brainstem. Among the syndromes, EIEE brains showed the most expanded lesions. Tyrosine hydroxylase-immunopositive cells and fibers were not demonstrated in EIEE, but were detected in WS. Reduced tyrosine hydroxylase immunoexpression in the EIEE brains was in the putamen, globus pallidus, and substantia nigra. Tryptophan hydroxylase immunoreactivity was reduced in the three epileptic syndromes, but especially in EIEE. Reduced expression of tyrosine hydroxylase and tryptophan hydroxylase may demonstrate dysfunction of the catecholaminergic and serotonergic neurons. From this study, the lesions in EIEE were widespread, including in the lower brainstem and cerebellum, compared with in EME and WS. Dysfunction of the catecholaminergic and serotonergic systems could be suggested. These characteristic changes may lead to the pathophysiology of EIEE.

Early epileptic encephalopathy with suppression burst electroencephalographic pattern--an analysis of eight Taiwanese patients

Early epileptic encephalopathy with suppression burst (SB) comprises two distinct epileptic syndromes, early infantile epileptic encephalopathy (EIEE) and early myoclonic encephalopathy (EME). We reviewed etiologies, neurological outcome and clinico-electroencephalographic features of EIEE and EME. Chart records of early epileptic encephalopathy with SB from January 1997 to December 2000 were reviewed. These cases fulfilled the diagnostic criteria of EIEE and EME. Totally eight patients (four females, four males) were enrolled. They consisted of three cases of EIEE and five cases of EME. The follow-up periods ranged from 6 to 30 months. For EIEE, two cases had migrational disorders, and one was cryptogenic; for EME, three cases had non-ketotic hyperglycinemia (NKH), one was pyridoxine dependency and one was cryptogenic. The main initial seizure patterns were tonic spasms in EIEE, and were erratic myoclonus in EME. The age of seizure onset ranged from 26 h to 5 days after birth for EIEE, and 2 h to 7 days of life for EME. The SB pattern in the electroencephalography (EEG) was noted mainly during sleep state in EME, but in both awake and sleep states in EIEE. Asymmetric SB pattern and background activities in EEG were found in migrational disorders. The EEG in all cases of EIEE changed to hypsarrhythmia at 4-6 months of age. In EME, only the EEG in cases of NKH evolved to hypsarrhythmia. Response to anti-convulsants was generally poor. All had severe psychomotor retardation. Although EIEE and EME share several common features, differences in terms of seizure seminology and evolution, EEG patterns and etiologies still exist.

A case of Ohtahara syndrome with olivary-dentate dysplasia and agenesis of mamillary bodies

We report a patient with early infantile epileptic encephalopathy (EIEE) with suppression-burst (Ohtahara syndrome) associated with olivary-dentate dysplasia and agenesis of mamillary bodies is reported. Although those with Ohtahara syndrome are a heterogeneous group, virtually all reported cases are secondary to neuronal migrational disorders, sometimes only identified by detailed neuropathologic examination, as in this case report, which describes mamillary body agenesis as a not-yet-recognized anomaly associated with Ohtahara syndrome. All children with Ohtahara syndrome should have high-resolution magnetic resonance imaging (MRI) and detailed postmortem neuropathologic examinations.

Infantile epileptic encephalopathy (Ohtahara syndrome) and migrational disorder

A case of early infantile epileptic encephalopathy (EIEE) with suppression-bursts (Ohtahara syndrome) associated with a diffuse cerebral migrational and maturation disorder evident on microscopic examination is reported. Although virtually all reported cases of EIEE are secondary to a congenital or acquired structural malformation of cortical development, EIEE is sometimes identified only by detailed neuropathologic examination, as confirmed by this case report. In addition to the malformation of cortical development, the patient demonstrated an absence of gamma-aminobutyric acid in the cerebrospinal fluid. All children with EIEE should be thoroughly examined by magnetic resonance imaging, cerebrospinal fluid amino acid level determination, and detailed postmortem neuropathologic examination.

Recent advances and some problems in the delineation of epileptic syndromes in children

The current International Classification of Epilepsies and Epileptic Syndromes has classified a number of age-related epileptic syndromes in children, but some of these entities have not been well delineated and many syndromes not included in the International Classification have been proposed. This article is intended to supplement some of the currently listed childhood epileptic syndromes, discuss certain problems with the classification system, and review some of the proposed pediatric syndromes.