Cognitive deficits after cryptogenic infantile spasms with benign seizure evolution

Between 1989 and 1994, 18 children with cryptogenic infantile spasms-defined by normal development before onset of spasms, symmetrical hypsarrhythmia or multifocal spikes, and typical spasms on presentation, and no abnormal findings on aetiological studies including neuroradiology-were diagnosed and treated. To assess the risk of cognitive impairment later in life, 15 of these 18 children whose spasms completely resolved within the first year of life were studied. Age at onset of spasms varied between 4.4 and 9.8 months (mean 6.5 months). Children were effectively treated with adrenocorticotrophic hormone (10 children), pyridoxine (three), vigabatrin (one), or sodium valproate (one). Spasms lasted between 11 and 138 days (mean 50 days) and stopped between the age of 6.3 and 10.2 months(mean 8.1 months). EEGs normalized between the age of 7.1 and 13.2 months (mean 9.4 months). Early development was assessed on presentation and within a few months after spasms had stopped. A detailed neuropsychological assessment was performed between the age of 4.0 and 5.9 years. Twelve children had normal intelligence; specific cognitive deficits were found in five. Three children had mild learning disability. Abnormal developmental status at age 8 to 15 months after complete resolution of spasms and EEG abnormalities was associated with cognitive deficits at age 4 to 6 years.     

Non-convulsive status epilepticus and audiogenic seizures complicating a patient with asymmetrical epileptic spasms

A female infant suffered from epilepsy since the neonatal period, which evolved into West syndrome at the age of 2 months. Spasms in series and hypsarrhythmia disappeared after treatment with high-dose phenobarbital; however, single spasms persisted with right-sided predominance, and polyspike activity in the left parieto-temporal areas preceded or coincided with these spasms. Magnetic resonance imaging revealed a small calcification in the right occipital area, and positron emission tomography showed hypometabolism over the right hemisphere. Widespread epileptic discharges gradually increased on electroencephalography (EEG) during sleep thereafter. The patient presented with daytime unresponsiveness at 1 year and 6 months, when diffuse, irregular spike and wave activity characterized the waking EEG. Spasms or brief tonic seizures with right-sided predominance were provoked by auditory stimuli during this period, particularly by her mother’s voice, with ictal EEG of right posterior predominant fast activity and subsequent desynchronization. The administration of clobazam resulted in the marked improvement of EEG findings and transient disappearance of spasms. Presumably, certain patients with asymmetrical epileptic spasms may be regarded as a unique type of localization-related epilepsy, and can show an unusual course of evolution in comparison to other cases of epilepsy that evolve after West syndrome.     

Transient left temporal lobe lesion in Menkes disease may influence the generation of tonic spasms

We report a 7-month-old boy with Menkes disease who presented West syndrome. Magnetic resonance imaging (MRI) revealed atrophy of the frontal and parietal lobes, subdural hematoma on the right side, and left temporal lobe lesion (low intensity in T1-weighted imaging (T1-WI), high intensity in T2-weighted imaging (T2-WI) and low intensity in diffusion-weighted imaging (DW-I)) at 7 months of age. The apparent diffusion coefficient (ADC) was 1.68 × 10⁻³ mm²/s in the left temporal lobe lesion and 1.15 × 10⁻³ mm²/s on the contralateral side. ¹H-magnetic resonance spectroscopy (¹H-MRS) revealed a decrease in N-acetylaspartate/(creatine + phosphocreatine) (NAA/Cr) (0.71) and a lactate peak in the left temporal lobe lesion. At 8 months of age, the left temporal lobe lesion disappeared, the ADC of this lesion was within the normal range (1.10 × 10⁻³ mm²/s), and ¹H-MRS revealed a slight increase in NAA/Cr (1.12) and disappearance of the lactate peak. We suspected that the transient temporal lobe lesion in Menkes disease was mainly vasogenic edema. Electroencephalography (EEG) revealed left hemisphere dominant hypsarrhythmia and slowing in the left hemisphere. Ictal EEG revealed generalized slow wave burst with P3, T3 spike antecedence and the antecedent spike was consistent with left temporal lobe lesion. After disappearance of the left temporal lobe lesion, tonic spasms disappeared and EEG findings improved. In this case, the clinical course and ictal EEG suggested that epileptic activity from the left temporal lobe lesion may have given rise to tonic spasms.     

Cardio-facio-cutaneous syndrome with infantile spasms and delayed myelination

A girl with cardio-facio-cutaneous (CFC) syndrome due to a BRAF gene mutation (c.1454T→C, p.L485S) experienced repetitive epileptic spasms at the corrected age of 4 months. Electroencephalograms revealed hypsarrhythmia, and magnetic resonance imaging identified delayed myelination and a hypoplastic corpus callosum. Various antiepileptic treatments, including adrenocorticotropic hormone therapy, were ineffective, although transient seizure control was achieved by a ketogenic diet and clorazepate dipotassium. However, seizures with epileptic foci at the bilateral posterior temporal areas re-aggravated and remained intractable; severe psychomotor delay persisted. This case indicated that infantile spasms in CFC syndrome can be difficult to control and may be accompanied by severe psychomotor retardation and abnormal myelination.     

Electro-clinical features and magnetic resonance imaging correlates in Menkes disease

Background: Epilepsy is an early and important feature in Menkes disease (MD), an X-linked recessive neurodegenerative disorder of childhood with defect in copper metabolism. There are only few reports on the electro-clinical and magnetic resonance imaging correlates in Menkes disease. The current study describes the electro-clinical features in MD in relation with the structural findings on MRI. Patients and Methods: Six patients from five families were evaluated between 2005 and 2011. Their diagnosis was based on the characteristic morphological features, microscopic evidence of pili torti and low copper and ceruloplasmin levels. All the patients underwent MRI and EEG as part of the evaluation. Results: All patients had classical form of MD with typical morphological features. All but one patient had refractory seizures. Seizure types included multifocal clonic seizures (n = 3), myoclonic jerks (n = 4) and tonic spasms (n = 1). EEG was markedly abnormal in all except in the patient without clinical seizures. While focal epileptiform discharges predominated before six months of age modified hypsarrhythmia was characteristically noted thereafter. MR Imaging revealed abnormalities in all patients, with cerebral atrophy and delayed myelination being the most common observations. Other features noted were subdural effusion (n = 3), leukoencephalopathy (n = 3) and basal ganglia signal changes (n = 1). Follow up imaging in three patients showed resolution of white matter signal intensity changes. Conclusions: Electro-clinical features in Menkes disease are age dependent and evolve sequentially. White matter changes coincided with acute exacerbation of seizures. There was fair correlation between the electro-clinical features and structural findings on MRI.     

A case of infantile Alexander disease diagnosed by magnetic resonance imaging and genetic analysis

We encountered a male infant with infantile Alexander disease presenting with megalencephaly and hydrocephalus as a neonate and subtle seizures at 3 months of age. At 6 months of age, bulbar paralysis appeared. Brain magnetic resonance imaging (MRI) showed abnormal findings with white matter involvement and a characteristic periventricular rim, satisfying the diagnostic criteria proposed by van der Knaap, except for MRI contrast. R239H mutation of glial fibrillary acidic protein gene was identified, representing a common cause of infantile-type Alexander disease.     

Identification of infants at risk for infantile spasms by neonatal polygraphy

Reevaluation of neonatal EEGs and polygraphic tracings of 40 infants with infantile spasms and/or hypsarrhythmia resulted in the constitution of a compound score for the identification of infants at risk for infantile spasms by neonatal EEG. The score comprises 8 distinct items: 2 concern behavioral characteristics, 6 abnormality of EEG background activity and paroxysmal events. A tracing registered at conceptional age 36 to 44 weeks (eventually up to 50 weeks) presenting at least 4 of these 8 items is scored positive for the risk of evolving hypsarrhythmia. In a prospective study the polygraphic tracings of 941 newborn infants were evaluated for risk: 18 infants suffering from perinatal distress and 7 newborns with malformations of the brain were scored positive and all 25 developed infantile spasms and/or hypsarrhythmia. One infant with later infantile spasms was missed by the scoring system. None of the remaining infants scored negative manifested infantile spasms. Thus, correct positive prognostication was 100% and false negative 0.1%. By conventional EEG 5 out of 8 patients with infantile spasms were correctly predicted. The high validity of the risk-score based on polygraphic tracing between conceptional age 36 to 44 weeks may allow pre-onset treatment preventing secondary mental deterioration due to hypsarrhythmia and infantile spasms.     

Factors associated with treatment lag in infantile spasms

Aim The aim of this study was to evaluate the conditions in which infantile spasms are diagnosed and their possible impact on the course of the disease. Method We carried out a retrospective study of the reasons for delayed treatment of infantile spasms (treatment lag) in western France over the period 1990–2003. A total of 156 infants, 87 male (55%) and 69 female (45%), with infantile spasms were identified, in 45 (29%) of whom the spasms were symptomatic. They were aged 1 week to 24 months (median 20wks, mean 22.4, SD 13.3) at first symptoms. To be included in the study, participants had to exhibit a combination of clusters of spasms, altered psychomotor development, and paroxysmal electroencephalographic (EEG) activity, as defined by the International League Against Epilepsy. We did not restrict onset to the first year of life as infantile spasms may begin after the age of 1 year. Results The mean time from appearance of first symptom to first visit to a medical practitioner was 4 weeks. In 14% of cases, the reason for the visit was non‐neurological, the parents having noticed no neurological symptoms before the visit. The diagnosis was missed at first visit in 38% of the cases examined, with the incorrect diagnosis mostly commonly being gastro‐oesophageal reflux or no abnormality. This increased to 74% after a second visit, in all cases based on an abnormal EEG. However, in 5% the time between first presentation and diagnosis was over 2 months and up to 10 visits were required. The time lag between first presentation and diagnosis was significantly longer for individuals presenting to general practitioners than to paediatricians (p=0.03). Response to treatment was poorer in those in whom diagnosis was delayed. Interpretation Various steps could be taken to reduce treatment lag such as training general practitioners, informing the parents of individuals at risk about the possibility of infantile spasms, and recommending that EEG is performed before brain imaging in children with unexplained psychomotor delay.     

Registry initiated to characterize vision loss associated with vigabatrin therapy

The vigabatrin patient registry was implemented in August 2009 in conjunction with Food and Drug Administration approval of vigabatrin. All US vigabatrin-treated patients must enroll in the registry. Data on prescriber specialty/location, patient demographics, and clinical characteristics are collected. Benefit-risk assessments are required early in the course of therapy. Vision assessments are required at baseline (≤ 4 weeks after therapy initiation), every 3 months during therapy, and 3 to 6 months after discontinuation. As of February 1, 2011, 2473 patients (1500 with infantile spasms, 846 with refractory complex partial seizures, 120 with other diagnoses) had enrolled; 30.4% were previously exposed to vigabatrin. Kaplan-Meier analysis of time in registry indicated that 83 and 97% of all enrolled patients with refractory complex partial seizures and infantile spasms remained beyond 3 and 1 month, respectively. The ongoing registry will provide visual status and other information on vigabatrin-treated patients for both the infantile spasm and refractory complex partial seizure indications.     

Clinical and ictal characteristics of infantile seizures: EEG correlation via long-term video EEG monitoring

Purpose

The semiology of infantile seizures often shows different characteristics from that of adults. We performed this study to describe clinical and ictal characteristics of infantile seizures at less than two years of age.

Methods

A retrospective study was done for infants with epilepsy (ages: 1–24 months) who underwent long-term video electroencephalography (EEG) monitoring at Samsung medical center between November 1994 and February 2012. We analyzed the clinical and ictal characteristics of the 56 cases from 51 patients.

Results

In 69% of the patients, the seizure onset was before six months of age and the etiology was symptomatic in one third of the patients. Twelve seizure types were identified; spasms (24%), unilateral motor seizures (18%), and generalized tonic seizures (15%) were the three frequent types of seizure.All partial seizures were well correlated with the partial-onset ictal EEG, however 19.4% (7/36) of clinically generalized seizures revealed partial-onset ictal EEG. About one-thirds (4/11) of generalized tonic seizures had its ictal onset on unilateral or bilateral frontal areas and two out of seven generalized myoclonic seizures showed unilateral frontal rhythmic activities. Hypomotor seizures mainly arose from the temporal areas and hypermotor seizures from the frontal regions.

Conclusions

Even though most of the seizure semiology of infants is well correlated with ictal EEG, some of the generalized tonic seizures or myoclonic seizures revealed partial-onset ictal EEG suggesting localized epileptic focus. Accurate definition of seizures via video EEG monitoring is necessary for proper management of seizures in infancy, especially in some clinically generalized seizures.     

Prognostic factors of infantile spasms: Role of treatment options including a ketogenic diet

Objectives: The aim of this study was to provide additional evidences on prognostic factors for infantile spasms and the possible role of a ketogenic diet. Methods: A retrospective analysis was performed for patients with infantile spasms who had been followed up for more than 6 months between January 2000 and July 2012 at Samsung Medical Center (Seoul, Republic of Korea). We analyzed the association between possible prognostic factors and seizure/developmental outcomes. Results: Sixty-nine patients were included in this study and their mean follow-up duration was 52.5 (9–147) months. In the patients who had been followed up for more than 2 years, 53.6% (n = 30/57) remained seizure-free at the last visit. Sixty patients (86.9%) showed developmental delay at last follow-up. Forty-two patients (60.9%) became spasm-free with one or two antiepileptic drugs, one patient with epilepsy surgery for a tumor, and seven patients with a ketogenic diet after the failure of two or more antiepileptic drugs. The etiology and age of seizure onset were the significant prognostic factors. Conclusions: In this study, about 60% of the patients became spasm-free with vigabatrin and topiramate. Ketogenic diet increased the rate by 10% in the remaining antiepileptic drug resistant patients. However, 86.9% of the patients showed developmental delay, mostly a severe degree. Early diagnosis and prompt application of treatment options such as antiepileptic drugs, a ketogenic diet or epilepsy surgery can improve outcomes in patients with infantile spasms.     

Infantile spasms in a patient with williams syndrome and craniosynostosis

A patient with Williams syndrome, craniosynostosis, and infantile spasms is described. At age 6 months, the infant demonstrated infantile spasms and craniosynostosis and was operated on for craniosynostosis and treated with adrenocorticotropic hormone (ACTH) for the infantile spasms. ACTH completely controlled the seizures, but was halted because of the progression of ventricular hypertrophy. The seizure returned, and he was found to have elfin face, failure-to-thrive, developmental delay, and dental malformation in addition to congenital heart defects. High-resolution chromosome analysis revealed interstitial deletion of 7q11.22-q11.23. Therefore his clinical and cytogenetic diagnosis was Williams syndrome. Thyrotropin-releasing hormone (TRH) therapy reduced his seizures and improved the findings of EEG without cardiac side effects. In addition, his psychomotor development was slightly improved.     

Pedaling automatism in atypical West syndrome: a case report]

A seven-month-old girl with atypical West syndrome with pedaling automatism was reported. She started to have early infantile epileptic encephalopathy with suppression-burst (EIEE) at age 14 days followed by infantile spasms at 3 months of age. She began to have spasms with automatism at 4 month, mainly consisting of pedaling movements of both feet associated with tonic spasms of upper extremities and writhing of trunk. Ictal EEG showed irregular slow waves with occasional spikes predominantly over the right hemisphere mixed with artifacts. Interictal EEG during sleep showed suppression-burst patterns. Cerebral atrophy and microcephaly were revealed on brain CT, immature myelination on MRI and decreased blood flow in the frontal, temporal, and parietal lobes on the right on PET scan. Pedaling automatism is rare in infancy and its clinical significance was discussed in relation to West syndrome and complex partial seizures.     

Epilepsy in children with delayed presentation of perinatal stroke

A subgroup of children with perinatal stroke do not present clinically until after the perinatal period. Detailed epilepsy outcomes in these children have not been well studied. A retrospective cohort study of 45 children with delayed presentation of perinatal stroke identified by review of pediatric stroke clinic records, physician referral, and International Classification of Diseases, Ninth edition, code searches of hospital records, was performed at a tertiary pediatric hospital in Indianapolis, Indiana. A modified version of the Engel scale was used to grade epilepsy outcomes. The chi(2) test, Fisher's exact test, and relative risks were calculated to examine the association of epilepsy at time of last follow-up with initial presentation with seizures, infantile spasms, radiographic findings, and initial abnormal electroencephalogram (EEG). These tests were also used to examine the association of epilepsy with cognitive or motor disability and the association of initial abnormal EEG with motor disability. Patients presented with hemiparesis (40; 89%), seizures (4; 9%), or headaches (1; 2%). All had unilateral infarcts on cranial imaging. Four children (9%) had infantile spasms, 2 at presentation and 2 later. Nineteen children received at least 1 EEG for suspicious spells or frank seizures; initial EEG was abnormal in 16 patients (84%). At last follow-up, 17 patients (38%) had epilepsy, which was severe in 4 (24% of those with epilepsy). Initial presentation with seizures (relative risk = 3.2; 95% confidence interval, 2.0-4.9) and infantile spasms (relative risk = 3.2; confidence interval, 2.0-4.9) were associated with epilepsy at last follow-up. Infantile spasms were also associated with moderate-to-severe epilepsy at last follow-up (relative risk = 10.3; confidence interval, 1.9-54.4). Epilepsy at last follow-up was associated with cognitive disability (P = .05). Initial abnormal EEG was not associated with cerebral palsy (P = .30). Epilepsy is frequent in children with delayed presentation of perinatal stroke and is associated with initial presentation with seizures and infantile spasms at any point in time. Cognitive disability often accompanies epilepsy in these children.     

Epilepsy and the Electroencephalogram in Progressive Encephalopathy with Edema, Hypsarrhythmia, and Optic Atrophy (the PEHO Syndrome)

Summary: Progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO syndrome) is an apparently autosomal recessive disorder manifested by infantile spasms, severe hypotonia, and early arrest of psychomotor development. Subcutaneous edema in the limbs, typical facial features, and blindness with optic atrophy are also present. Neuropathologic and radiographic studies show progressive brain atrophy, which is accentuated infratentorially. We recorded 85 EEGs from 10 patients between the ages of 3 weeks and 12.7 years; follow-up ranged from 7 months to 12.1 years. The infantile spasms were preceded by other neurological symp- toms in all patients. Seven of nine patients showed focal or generalized epileptiform activity or abnormal EEG background. All patients developed hypsarrhythmia, first recorded between 3 and 11 months of age, that was resistant to therapy with ACTH and antiepileptic drugs. After the hypsarrhythmia disappeared, five patients showed slow spike-wave activity generally seen in the Lennox-Gastaut syndrome, and three patients showed background EEG abnormality with generalized or diffuse paroxysmal activity. There were no specific EEG features that could help in the diagnosis of PEHO. The PEHO syndrome should be borne in mind in the diagnostic work-up of patients with infantile spasms, so that potentially harmful treatment can be avoided, and the parents can be counseled about the inheritability of the disorder.     

Benign familial neonatal convulsions in a family with one member with infantile spasms]

A pedigree of benign familial neonatal convulsions (BFNC) was reported. Seven members of two generations experienced convulsions in the neonatal period and/or in early infancy. All of these members except one had a good prognosis. One member who had infantile spasms was uneventfully delivered at 37 weeks of gestation, with a birth weight of 2,562 g and, without trouble during pregnancy. At the age of 20 days, she began to have adversive seizures. Later, she developed complex partial seizures and infantile spasms at 1 month and 10 days of age. Interictal EEG showed hypsarrhythmia. Biochemical investigations and MRI of the head revealed no abnormality. Treatment with sodium valproate and carbamazepine succeeded in stopping the seizures and she had no seizures after 3 months. But her psychomotor development was moderately delayed at 8 months. No case with severe epilepsy such as infantile spasms has been reported in the previous literature on BFNC. From our experience, early treatment and careful follow-up are considered to be important for BFNC.     

Epilepsy in Menkes disease: analysis of clinical stages

PURPOSE: Epilepsy is one of the main features of Menkes disease (MD), although it is not described in depth. To determine the spectrum of epilepsy, we studied its main characteristics. METHODS: Based on clinical charts, we retrospectively analyzed the evolution of electroclinical features of 12 patients with confirmed MD. RESULTS: Epilepsy could be divided into three periods: (a) an early stage (median age, 3 months), characterized by focal clonic status epilepticus, usually triggered by fever (10 patients). Ictal EEG showed runs of slow spike-waves and slow waves in the posterior regions, and interictal EEG multifocal and polymorphic slow waves (three cases), or mixed slow spike-waves and slow waves (seven cases). Partial seizure control was obtained in nine patients during 5.9 months; (b) an intermediate stage (median age, 10 months) with intractable infantile spasms (11 patients) in which interictal EEG demonstrated modified hypsarrhythmia (seven cases), diffuse irregular slow waves and spike-waves (four cases). Six patients died at the median age of 15 months; and (c) a late stage in the six remaining patients (median age, 25 months), with multifocal seizures, tonic spasms, and myoclonus in four patients, whereas two patients became seizure free. Interictal EEG showed multifocal high-amplitude activity, mixed with irregular slow waves in all six cases. These patients died at the median age of 3.6 years. CONCLUSIONS: Based on a relatively large series of MD patients with a quite prolonged survival, we individualized three successive periods in the course of epilepsy: early focal status, then infantile spasms, and then myoclonic and multifocal epilepsy after age 2 years.     

Benign myoclonus of early infancy: an imitator of West's syndrome

Benign myoclonus of early infancy is a rare condition characterized by nonepileptic spasms that may resemble the epileptic spasms seen in West's syndrome. The spells in benign myoclonus of early infancy begin before age 1 year and are self-limited. The electroencephalogram (EEG) is invariably normal, and neurologic development is not affected. West's syndrome is characterized by infantile spasms that appear before 1 year of age, an abnormal EEG with hypsarrhythmia, and a poor prognosis. We describe six infants who presented for evaluation of clusters of head, trunk or extremity spasms, eye blinking, brief jerking of upper extremities or trunk, and head nodding episodes. In most, a presumptive diagnosis of West's syndrome was made prior to the referral. One infant had been placed on valproate. Routine EEG recordings or prolonged video EEG monitoring were normal both during and between episodes. After the negative evaluations, the diagnosis of benign myoclonus of early infancy was made in each infant. Subsequently, no infant was treated with anticonvulsants. Follow-up revealed complete resolution of the episodes in all children within 2 weeks to 8 months of onset. All had normal neurologic development. Based on our cases and review of the literature, the prognosis for this disorder is excellent. Care should be taken to recognize this rare entity and avoid unnecessary and potentially harmful antiepileptic therapy.     

Brain malformation and infantile spasms in a SCAD deficiency patient

This report presents a case of short-chain acyl-coenzyme A (CoA) dehydrogenase deficiency with a previously unreported presentation with brain malformations and infantile spasms. This female infant developed repeated tonic clonic seizures at the age of 3(1/2) months. She subsequently developed West syndrome at the age of 4 months. Her electroencephalogram disclosed hypsarrhythmia, and video-electroencephalographic monitoring confirmed the presence of infantile spasms. Magnetic resonance imaging revealed a small midline frontal meningocele, abnormal cortical gyration, and partial agenesis of the corpus callosum consistent with neuronal migrational disorder. Metabolic evaluation indicated ethylmalonic acidemia. Muscle biopsy with enzymatic assay of short-chain acyl-coenzyme A revealed low enzymatic activity confirming the diagnosis of short-chain acyl-coenzyme A dehydrogenase deficiency. To our knowledge, this is the first report of the coexistence of short-chain acyl-coenzyme A dehydrogenase deficiency, infantile spasms, and brain malformation. We conclude that short-chain acyl-coenzyme A dehydrogenase deficiency should be considered in the differential diagnosis of gyral abnormality, corpus callosal hypoplasia, and infantile spasms.     

A long-term,clinical study on symptomatic infantile spasms with focal features

Background: We studied the clinical, neuroradiological and EEG characteristics of patients with infantile spasms (IS) who showed focal features to reveal their long-term prognoses and treatment responses. Subjects and methods: Subjects included 69 patients with IS who consecutively visited our hospital. We tentatively classified the subjects into focal IS (fIS) and diffuse WS (dIS) groups based on the presence and absence of more than two of the following findings, respectively: (1) epileptic spasms (ES) that were asymmetric, (2) a focal epileptic EEG abnormality, (3) a lateralized neurological abnormality, (4) a focal brain MRI and (5) a focal SPECT abnormality. Results: We found 23 cases with fIS and 46 cases with dIS. ES responded more frequently in fIS than dIS group (100% vs. 80%; P = 0.02) to the initial ACTH trial although the subsequent seizure relapse occurred more frequently in fIS than dIS group (74% vs. 38%; P = 0.0006). The second course of ACTH trial brought a short as well as long-term remission in both groups (6/8 cases vs. 5/6 cases). Later in the clinical course, the fIS patients tended to display a focal epileptic EEG abnormality and to develop focal seizures. In our series, approximately one-third of patients with fIS later showed either only a focal epileptic EEG abnormality, a focal epileptic EEG abnormality with focal seizures, or bilateral asymmetric EEG foci with disabling seizures, respectively. Conclusion: It is useful to classify patients with IS into fIS and dIS groups based on various lateralizing signs because the classification provides practical information regarding the long-term outcome and treatment strategy.