Infantile spasms syndrome in monozygotic twins

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

Infantile spasms syndrome, West syndrome and related phenotypes: what we know in 2013

The current spectrum of disorders associated to clinical spasms with onset in infancy is wider than previously thought; accordingly, its terminology has changed. Nowadays, the term Infantile spasms syndrome (ISs) defines an epileptic syndrome occurring in children younger than 1 year (rarely older than 2 years), with clinical (epileptic: i.e., associated to an epileptiform EEG) spasms usually occurring in clusters whose most characteristic EEG finding is hypsarrhythmia [the spasms are often associated with developmental arrest or regression]. The term West syndrome (WS) refers to a form (a subset) of ISs, characterised by the combination of clustered spasms and hypsarrhythmia on an EEG and delayed brain development or regression [currently, it is no longer required that delayed development occur before the onset of spasms]. Less usually, spasms may occur singly rather than in clusters [infantile spasms single-spasm variant (ISSV)], hypsarrhythmia can be (incidentally) recorded without any evidence of clinical spasms [hypsarrhythmia without infantile spasms (HWIS)] or typical clinical spasms may manifest in absence of hypsarrhythmia [infantile spasms without hypsarrhythmia (ISW)]. There is a growing evidence that ISs and related phenotypes may result, besides from acquired events, from disturbances in key genetic pathways of brain development: specifically, in the gene regulatory network of GABAergic forebrain dorsal-ventral development, and abnormalities in molecules expressed at the synapse. Children with these genetic associations also have phenotypes beyond epilepsy, including dysmorphic features, autism, movement disorders and systemic malformations. The prognosis depends on: (a) the cause, which gives origin to the attacks (the complex malformation forms being more severe); (b) the EEG pattern(s); (c) the appearance of seizures prior to the spasms; and (d) the rapid response to treatment. Currently, the first-line treatment includes the adrenocorticotropic hormone ACTH and vigabatrin. In the near future the gold standard could be the development of new therapies that target specific pathways of pathogenesis. In this article we review the past and growing number of clinical, genetic, molecular and therapeutic discoveries on this expanding topic.

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.

Simultaneous onset of infantile spasms in monozygotic twins

The clinical, electroencephalographic, and genetic findings are reported for three pairs of monozygotic twins who developed infantile spasms in their first year. In all three pairs, the spasms started on the same day in each member of the pair. Neither sequencing of the ARX and CDKL5 (alias STK9) genes nor array comparative genomic hybridization assessment revealed any abnormalities. The long-term outcome was poor in all twins, although with different severity in individual pairs. These findings suggest that genes other than those currently known likely play a role in predisposition to infantile spasms, and that genetic susceptibility is linked to a variable phenotypic expression, ranging from quite benign to very severe, in monozygotic twins with no other apparent risk factors.

Clinical and pedigree study on familial cases of West syndrome in Japan

Nationwide survey on familial cases of West syndrome (WS) in first- and second-degree relatives was conducted by mailing a questionnaire to 64 major university hospitals, children's hospitals, and epilepsy centers in Japan, and by review of the Japanese cases in the literatures. Thirty-four familial cases, 20 males and 14 females, were obtained in 15 families including one with five affected members in two generations and another with three affected male siblings including a half brother by a different father (X-linked WS). A mother and the child or children were involved in three families. Nine families had 21 cryptogenic cases and six families had 13 symptomatic cases, and the etiologies were same among the affected members in each family. Familial cases of WS have characteristic clinical features and genetic mechanisms. Age of onset, seizure types, electroencephalographic abnormalities, early seizure outcome, effective treatment, long-term seizure prognosis, and long-term developmental prognosis were concordant among the affected members in each family. Long-term seizure and developmental prognoses were far better than those in WS in general, with seizure-free rate of 82% and normal mental development rate of 44%. Poor prognosis was limited to specific symptomatic cases. Adrenocorticotropic hormone (ACTH) was a treatment of choice, and even in relapse of WS after ACTH therapy, the patients well responded to antiepileptic drugs. Specific inheritance pattern was difficult to imagine in the majority of the present cases, except for one family with X-linked WS and another family with five patients of maternal inheritance. These results are helpful for the treatment choice and prognostication of clinical course for familial cases of WS.

Familial idiopathic West syndrome

Two families, each with occurrence of West syndrome in two siblings, are presented. Monozygotic twins in family 1 developed infantile spasms at the age of 4 months. Two female siblings in family 2 started to have seizures at the age of 6 months, but 2 years apart. The family history; development prior to West syndrome; clinical, electroencephalographic, and neuroradiologic findings; diagnostic work-up; and treatment are described. The outcome in family 1 (follow-up after 2 years) showed no conspicuous findings on physical and neurologic examination, and psychomotor development appropriate to cognitive, motor, and language developmental age in both twins. In family 2 (follow-up after 3 and 5 years), the older sister only was one standard deviation below mean in intellectual developmental age. Simultaneous occurrence of infantile spasms in both siblings from these two families but with variable clinical expression suggests there is a genetic susceptibility and variable phenotypic expression. Long-term follow-up will demonstrate whether these cases may be classified as "familial idiopathic West syndrome."

Genetic predisposition to West syndrome

To determine the recurrence risk of West syndrome (WS), we studied the familial antecedents of consecutively referred patients. Among siblings, there was an increased incidence of WS but not of febrile convulsions. Familial incidence of epilepsy was intermediate between the epileptic and nonepileptic control groups. When cases resulting from a genetically determined disease were excluded, incidence of epilepsy among siblings was similar to that in normal controls. Five of the 11 familial cases of WS were due to an identifiable cause: twin pregnancy, tuberous sclerosis, and recurrent maternal toxemia. In 4 of the remaining families, the clinical picture included spasms, erratic myoclonus, and postnatal microcephaly, suggestive of a previously unidentifiable progressive encephalopathy. Therefore, when identifiable familial diseases were excluded, the recurrence risk was < 1%.

Infantile spasms and neuronal heterotopias. A report on six cases

Six infants with infantile spasms are presented, three primarily considered idiopathic and three symptomatic. Autopsy unexpectedly revealed heterotopias, cortical dyslamination, and other brain malformations in all six cases. No history of any etiologic moment during the neuronal migratory period of early gestation was found. It is concluded that wide-spread disturbances of CNS morphology should always be considered in cases of infantile spasms.

Nephrosis and disturbances of neuronal migration in male siblings--a new hereditary disorder?

Two male siblings (a boy aged 2 years 10 months at death and a male fetus aborted in gestational week 22) showed similar brain and kidney malformations, comprising paraventricular heterotopias, central canal abnormalities (including hydrocephalus in the boy), and glomerular kidney disease with proteinuria. There were no known hereditary diseases in the families of the parents, and there was one healthy sibling of either sex. The malformations thus seem to be hereditary in an autosomal or possibly X linked recessive fashion.

Infantile spasms syndrome in monozygotic twins. A 7-year follow-up

The Infantile Spasms Syndrome is a fairly common form of seizures in infancy. Many papers and several books have been published on this syndrome but several aspects are still obscure. In particular, there is some controversy about anticonvulsant treatments and on the question of improvements in mental status. An unusual case of 2 monozygotic twins with by this syndrome, both with clinical manifestations appearing within a few hours on the same day, at 6 months has been followed up for 7 years, giving us the opportunity to understand some aspects of the clinical course of the disease and long term treatment.