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

'Benign focal epilepsy in infancy with vertex spikes and waves during sleep'. Delineation of the syndrome and recalling as 'benign infantile focal epilepsy with midline spikes and waves during sleep' (BIMSE)

PURPOSE

To better delineate the electroclinical features of infants who presented with focal seizures and typical midline sleep EEG abnormalities with a benign outcome. We discuss the significance of the typical EEG marker in non-epileptic patients.

METHODS

Patients were selected from a group of epileptic subjects with seizure onset less than 3 years we observed from 1st November 1990 and 31st December 2003. Inclusion criteria were the presence of typical sleep EEG marker and focal seizures with benign outcome. Cases with less than 18 month follow-up period were excluded from this study.

RESULTS

There were 19 patients (12 males, 7 females). Pre-, peri- and post-natal personal history was negative in all patients. Psychomotor development was normal, both before and after seizure onset. Neuroradiological investigations gave normal results. Seizure manifestations were typical, characterized by cyanosis, staring and rare lateralizing signs, of short duration. Age at onset was comprised between 4 and 30 months. The typical EEG marker, a spike followed by a bell-shaped slow-wave, localized in the midline regions, was present in all subjects only during sleep. All had a favorable outcome and the overwhelming majority of the patients were not treated.

CONCLUSIONS

Our patients have an homogeneous electroclinical picture to constitute a new epileptic syndrome not included in the ILAE classification. We propose to call it 'benign focal epilepsy in infancy with midline spikes and waves during sleep' (BIMSE).

Short duration of benign partial epilepsy in infancy

It has previously been reported that benign partial epilepsy in infancy constitutes up to 29% of the epilepsies presenting in the first 2 years of life. To determine the proportion of benign partial epilepsy in our epilepsy population, we retrospectively reviewed 331 patients with greater than two afebrile seizures in the first 2 years of life between 1993 and 2000. Inclusion criteria were (1) partial seizures with or without secondary generalization, (2) normal development, (3) no other neurologic abnormalities, (4) normal interictal electroencephalograms (EEGs), and (5) good response to treatment. Exclusion criteria included seizures that (1) were caused by acute central nervous system insult, (2) occurred only within the first month of life, and (3) lasted longer than 30 minutes. Of 331 patients, 22 (6.6%) fulfilled the criteria with a minimum of 2 years and a mean of 4 years of follow-up off antiepilepsy drug treatment. Six (27%) had complex partial seizures, and 16 (73%) had complex partial seizures with secondary generalization. Neuroimaging studies were normal in all patients. Of the 6 patients with ictal EEGs, 3 had a temporal lobe focus, 1 had an occipital lobe focus, and the remaining 2 had dual foci. Median onset was 4.0 months (range 0.8-9.3). Seizures remitted within 4 months in 20 (91%). Mean duration of seizure persistence was 2.1 months (range 0-8.3) and was longer in treated patients. Median age at last seizure was 6.4 months (range 2-18). Nineteen were treated with antiepilepsy drugs. At last follow-up (mean duration of 52.2 months), all patients were seizure free and off antiepilepsy drugs. Benign partial epilepsy in infancy is an epilepsy syndrome of short duration and is easily recognized using accepted classification criteria. Benign partial epilepsy in infancy appears to be an idiopathic localization-related epilepsy with a favorable prognosis. The incidence in our population is not as common as previously reported. Based on our findings, we suggest weaning of antiepilepsy drugs 6 months after seizure onset.

Benign idiopathic partial epilepsies in infancy

In infancy, partial epilepsies have been considered with suspicion for their probable association with brain lesions. Japanese authors first described partial epilepsies in infancy with a favorable outcome and called them benign partial epilepsy in infancy with complex partial seizures. Similar, but familial, cases with onset during the first year of life were described some years later and called benign infantile familial convulsions. Similar familial cases with subsequent choreoathetosis were described in 1997 and called infantile convulsions and choreoathetosis. Benign infantile convulsions have also been described in association with mild gastroenteritis. Interictal electroencephalography (EEG) was always normal in all of these forms. More recently, a new epileptic syndrome characterized by partial seizures with onset between ages 13 and 30 months, a benign outcome, and characteristic EEG abnormalities in the vertex regions during sleep has been described. There is also an early-onset benign childhood occipital seizure susceptibility syndrome that can start in infancy.

Symptomatology of infantile spasms

Epileptic spasms in West syndrome consist of a brief phasic contraction followed by a gradually relaxing tonic component, associated with typical ictal electroencephalographic (EEG) patterns. Three different EEG patterns are associated with a clinical spasm: fast wave bursts, high voltage slow waves (HVS), and desynchronization, occurring in this order. HVS are consistently seen and correspond to a clinical spasm, but usually preceded by fast wave bursts, which may be associated with an inhibition of muscle activity. Epileptic spasms can be classified into: symmetric spasms, asymmetric/asynchronous spasms, focal spasms, spasms with partial seizures, subtle spasms, spasms preceded by brief atonia, or subclinical spasms. Although clinical spasms are usually symmetric, ictal fast waves are always localized, and the following slow waves are not bilaterally synchronous and generalized, suggesting a focal cortical origin of spasms.

A pilot study on benign partial epilepsy in children with complex partial seizures

In a review of 145 children with partial onset epilepsy, the authors were able to determine a focus of children whose complex partial seizures (CPS) ran a benign course, who had no identifiable lesion on scanning and whose EEG focus was not fixed, but tended to shift. The authors suggest that a benign form of CPS in children can be recognised.

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."

Benign partial epilepsy in infancy and early childhood with vertex spikes and waves during sleep: a new epileptic form

International epilepsy classification includes different epileptic syndromes with favourable outcomes in paediatric age, both partial and generalised. This is true in childhood while no partial benign forms are accepted in infancy. In 1987, Watanabe first described a new entity and he defined it as 'benign complex partial epilepsies in infancy'. In 1992, Vigevano referred similar but familial cases whose seizures had secondary generalisation. Both these forms had no interictal EEG abnormalities neither awake nor during sleep. This article presents a survey of 12 cases of partial epilepsy with favourable outcome differing from Watanabe and Vigevano's cases, both for the presence of interictal EEG abnormalities only during sleep and for seizure picture. All our patients are neurologically and neuroradiologically normal. Psychomotor development is unremarkable. Age onset range is 13-30 months. All cases present characteristic spikes and waves during slow-sleep in vertex cerebral areas. Awake EEG is always normal, at follow-up too. Our cases have such homogeneous electroclinical features as to hypothesise a new partial idiopathic epileptic syndrome with favourable outcome in infancy and early childhood. We propose to define it as 'benign partial epilepsy in infancy and early childhood with vertex spikes and waves' (BVSE).

Epileptic spasms preceded by partial seizures with a close temporal association

PURPOSE

To investigate the distinctive features of patients with West syndrome who had partial seizures followed by epileptic spasms (PS-ES).

METHODS

We examined 45 patients with West syndrome whose epileptic spasms were recorded with simultaneous video-electroencephalography (EEG) monitoring between 1982 and 1996. We investigated the patients who had PS-ES and compared the PS-ES patients with the 37 patients without PS-ES.

RESULTS

Of the 45 patients who had epileptic spasms in clusters (ES) and hypsarrhythmia on the interictal EEG, eight (17%) had ES preceded by partial seizures (PS) with a close temporal association. Seven of these eight were female patients. The underlying disorders were tuberous sclerosis (one patient), Aicardi syndrome (one), nonketotic hyperglycinemia (one), and focal cortical dysplasia (one). The etiology was unknown in the remaining four patients, but was suspected to be of prenatal origin in three. Three types of seizure sequence were identified: PS followed several seconds later by ES (two patients), alternating PS and ES starting with PS (three), and PS gradually replaced by ES with overlapping of the two (three). PS-ES disappeared or was replaced by other types of seizures in 1-34 months. Six patients could not walk, and all patients could not speak any sentences at age 3 years.

CONCLUSIONS

Compared with patients without PS-ES, those with PS-ES more often had organic brain lesions of prenatal origin, other types of seizures before the onset of ES, asymmetric hypsarrhythmia on the EEG, and poor psychomotor outcome.

Benign partial epilepsy in infancy with complex partial seizures (Watanabe's syndrome): 12 non-Japanese new cases

International epilepsy classification includes different epileptic syndromes with favourable outcomes in pediatric age. In addition to these, other forms probably exist and in various papers in international literature they are proposed as new entities. This article presents a survey of benign complex partial epilepsy in infancy, a new epileptic syndrome first proposed by Watanabe, in 1987. Our work represents the only description of non-Japanese cases although similar but familial cases had been referred by Vigevano in 1992. We present data for 12 children (aged up to 9 years) followed over 2 years who had all the typical clinical features characterizing Watanabe's cases. For all of them we obtained EEG seizure recordings demonstrating the partial nature of their fits, arising from occipital or temporal regions. Interictal EEG were completely normal, both in waking and sleep. Evolution demonstrated benign outcome and all the children are seizure-free (eight of them have already stopped all medication) and all have normal psychomotor development.

West syndrome: etiological and prognostic aspects

West syndrome is a multi-etiological condition. Recent progress in perinatal medicine and the recent development of new neuroimaging techniques may have changed the etiological panorama of West syndrome. Our recent study has disclosed an increasing percentage of the perinatal group and a decreasing percentage of the doubtful group. The increase of the perinatal group is due to an increased proportion of very low-birthweight infants and periventricular leucomalacia (PVL). Among various etiological factors added to the long list of causes of West syndrome, focal cortical dysplasia is another newly emerging etiological factor associated with this syndrome. Patients with unilateral focal dysplasia more commonly have partial seizures, but may show infantile spasms transiently during infancy. They may have partial seizures preceding, in combination with or following infantile spasms. Follow-up MRI is necessary to detect delayed myelination because it is not disclosed at common ages of onset of this syndrome. PET is useful to further differentiate the cryptogenic group. Although West syndrome is regarded as one of the intractable epilepsies, the prognosis differs widely according to etiology. Follow-up PET is also useful to predict seizure and psychomotor prognosis.