Febrile seizures in patients with complex partial seizures

Febrile seizures occurred in 14 of 155 (9%) out-patients with complex partial seizures. Twelve patients had prolonged or recurrent febrile seizures, convulsive status epilepticus or a transient postictal neurological deficit. Febrile seizures were associated with perinatal abnormalities, an earlier onset of epilepsy and with a poor seizure control. Recurrent febrile seizures or those with complicating features are associated with an unfavourable therapeutic outcome in adult patients with complex partial seizures.     

Seizures with Fever After Unprovoked Seizures: An Analysis in Children Followed from the Time of a First Febrile Seizure

Summary: Purpose: To determine how the onset of unprovoked seizures influences recurrence of seizures with fever in children followed from the time of a first febrile seizure.
Methods: In a prospective cohort of children (n = 428) identified at the time of a first febrile seizure, predictors of a second seizure with fever were identified. The occurrence of a first unprovoked seizure was treated as a time-dependent covariate in a Cox regression model rather than as a censoring point as it traditionally has been in the past.
Results: One hundred forty-three (33.4%) children had further seizures. Seven had further seizures with fever only after onset of unprovoked seizures. After adjustment was made for the four previously described predictors of recurrent febrile seizures (age at onset, family history, height of fever, and duration of fever), the onset of unprovoked seizures was associated with a rate ratio of 3.47 (p = 0.0015), indicating a large increase in the risk of further seizures with fever after onset of unprovoked seizures.
Conclusions: Young children who develop unprovoked seizures after a febrile seizure are at substantial risk for further seizures with fever. This may represent part of the spectrum of benign febrile seizures or it may represent the so-called "epilepsy triggered by fever" spectrum. It affects only a small proportion of children with febrile seizures; however, in some children, it may be useful information to consider when making treatment decisions.     

Epilepsy duration, febrile seizures, and cerebral glucose metabolism

PURPOSE: Studies using magnetic resonance imaging have shown that reduced hippocampal volume is associated with a history of febrile seizures, the duration of epilepsy, and the number of generalized tonic-clonic seizures. It is uncertain whether these factors have the same influence on functional as on structural measures of the integrity of the epileptogenic zone. METHODS: We used positron emission tomography (PET) with fluorine 18 2-deoxyglucose to study 91 patients with temporal lobe seizure foci localized by ictal video-EEG. PET was performed in the awake interictal resting state with ears plugged and eyes patched. We recorded surface EEG during injection (5 mCi) and the 30-min uptake period. We used a standard template to analyze PET scans. RESULTS: A significant negative relation was found between the duration of epilepsy and hippocampal glucose metabolism ipsilateral to the epileptic focus. Patients with a history of either any febrile seizures, or complex, or prolonged febrile seizures, did not have greater hypometabolism ipsilateral to the epileptic focus than did patients without a febrile seizure history. We found no effect of generalized tonic-clonic seizure history. CONCLUSIONS: Longer epilepsy duration is associated with greater hypometabolism, suggesting that epilepsy is a progressive disease.     

Febrile seizures

Febrile seizures are the most common form of childhood seizures, occurring in 2 to 5% of children in the United States. Most febrile seizures are considered simple, although those with focal onset, prolonged duration, or that occur more than once within the same febrile illness are considered complex. Risk factors for a first febrile seizure, recurrence of febrile seizures, and development of future epilepsy are identifiable and varied. Children with febrile seizures encounter little risk of mortality and morbidity and have no association with any detectable brain damage. Recurrence is possible, but only a small minority will go on to develop epilepsy. Although antiepileptic drugs can prevent recurrent febrile seizures, they do not alter the risk of subsequent epilepsy. This has led to a changing view of how we approach the treatment of these common and largely benign seizures. This chapter will review the current understanding of the prognosis and management of febrile seizures.     

Recurrence of febrile convulsions in a population-based cohort

The risk of recurrence after an initial febrile seizure was 25% in a population-based cohort of 639 children followed from their first febrile seizure. Prognostic factors were an increasing risk of recurrence with younger age at first febrile seizure, a first degree relative with febrile seizures and complex features of the first febrile seizure. The effect of complex features was modified by age at first febrile seizure and family history in that complex features alone did not increase risk of recurrence but further increased the risk for children under 18 months at first seizure and/or with a positive family history. The prognostic factors for all febrile convulsions recurrences were also prognostic for having subsequent complex febrile convulsions. Children with none of the prognostic factors had only a 3% risk of a future complex febrile seizure while children under 18 months at first febrile convulsion and a positive family history or complex features had about a 20% risk of a subsequent complex febrile seizure.     

Design and phenomenology of the FEBSTAT study

Purpose: Febrile status epilepticus (FSE) has been associated with hippocampal injury and subsequent hippocampal sclerosis (HS) and temporal lobe epilepsy. The FEBSTAT study was designed to prospectively examine the association between prolonged febrile seizures and development of HS and associated temporal lobe epilepsy, one of the most controversial issues in epilepsy. We report on the baseline phenomenology of the final cohorts as well as detailed aims and methodology. Methods: The “Consequences of Prolonged Febrile Seizures in Childhood” (FEBSTAT) study is a prospective, multicenter study. Enrolled are children, aged 1 month to 6 years of age, presenting with a febrile seizure lasting 30 min or longer based on ambulance, emergency department, and hospital records, and parental interview. At baseline, procedures included a magnetic resonance imaging (MRI) study and electroencephalography (EEG) recording done within 72 h of FSE, and a detailed history and neurologic examination. Baseline development and behavior are assessed at 1 month. The baseline assessment is repeated, with age‐appropriate developmental testing at 1 and 5 years after enrollment as well as at the development of epilepsy and 1 year after that. Telephone calls every 3 months document additional seizures. Two other groups of children are included: a “control” group consisting of children with a first febrile seizure ascertained at Columbia University and with almost identical baseline and 1‐year follow‐up examinations and a pilot cohort of FSE from Duke University. Key Findings: The FEBSTAT cohort consists of 199 children with a median age at baseline of 16.0 months (interquartile range [IQR] 12.0–24.0) and a median duration of FSE of 70.0 min (IQR 47.0–110.0). Seizures were continuous in 57.3% and behaviorally intermittent (without recovery in between) in 31.2%; most were partial (2.0%) or secondary generalized (65.8%), and almost all (98.0%) culminated in a generalized tonic–clonic seizure. Of the 199 children, 86.4% had normal development and 20% had prior febrile seizures. In one third of cases, FSE was unrecognized in the emergency department. The Duke existing cohort consists of 23 children with a median age of FSE onset of 18.0 months (IQR 14.0–28.0) and median duration of FSE of 90.0 min (IQR 50.0–170.0). The Columbia control cohort consists of 159 children with a first febrile seizure who received almost the same workup as the FEBSTAT cohort at baseline and at 1 year. They were followed by telephone every 4 months for a median of 42 months. Among the control cohort, 64.2% had a first simple FS, 26.4% had a first complex FS that was not FSE, and 9.4% had FSE. Among the 15 with FSE, the median age at onset was 14.0 months (IQR 12.0–20.0) and the median duration of FSE was 43.0 min (IQR 35.0–75.0). Significance: The FEBSTAT study presents an opportunity to prospectively study the relationship between FSE and acute hippocampal damage, the development of mesial temporal sclerosis, epilepsy (particularly temporal lobe epilepsy), and impaired hippocampal function in a large cohort. It is hoped that this study may illuminate a major mystery in clinical epilepsy today, and permit the development of interventions designed to prevent the sequelae of FSE.     

Unconsciousness and delirious behavior in children with febrile seizures

The aim of this study is to clarify the incidence and clinical features of prolonged unconsciousness and delirious behavior in children with febrile seizures. We studied 213 consecutive febrile seizures during 208 febrile episodes in 203 patients. The seizure manifestations, the duration of seizures, the duration of unconsciousness, and the presence or absence of delirious behavior were determined on the basis of interviews with the parents with the assistance of medical records. The duration of seizures was less than 5 minutes in 90.2% of the seizures. The duration of unconsciousness was less than 30 minutes in 93% of the seizures. Delirious behavior was observed in 2.0% of the patients. Delirious behavior appeared before febrile seizures, and its duration was not long. On multiple regression analysis, nongeneralized seizures, seizures of ≥5 minutes, and intravenous diazepam were demonstrated to be independently associated with prolonged unconsciousness. In conclusion, prolonged unconsciousness and delirious behavior are rare in children with febrile seizures. Careful diagnostic evaluation is necessary when a child with febrile seizures has associated prolonged unconsciousness or delirious behavior. Okumura A, Uemura N, Suzuki M, Itomi K, Watanabe K. Unconsciousness and delirious behavior in children with febrile seizures.     

Clinical evaluation of the patients with epilepsy following febrile convulsions

We studied clinical, EEG and developmental features of 46 epileptic children following febrile convulsions. Incidence of developing epilepsy was 9.9 percent. Eleven patients (group G) out of 46 had generalized epileptic seizures, and 34 patients (group P) had partial seizures. Febrile convulsions of early onset, partial seizures and postictal neurological symptoms were more striking in group P (p less than 0.05), whereas febrile convulsions of late onset and prolonged seizures were slightly dominant in group G. And EEG abnormalities were more frequent in group P (p less than 0.05). Group P patients had significant number of risk factors (complex features of febrile convulsions) than group G patients (p less than 0.01). The interval between the last febrile convulsion and subsequent epileptic seizures was shorter in group G (p less than 0.01). Although subsequent epileptic seizures were well controlled in the both groups (91% in group G and 82% in group P), intractable seizures were recognized in 9% of group P patients. The patients who had risk factors of prolonged seizures, postictal neurological symptoms and early onset manifested poor controlled epileptic seizures (p less than 0.01). Motor or mental deficits were more frequently associated with group P: in some patients they had been observed before the onset of febrile convulsions. These results suggest that pathogenesis of epilepsy following febrile convulsions may be different among various seizure types of subsequent epilepsy. And the risk factors during febrile convulsions may be related to the prognosis of subsequent epileptic seizures as well as the incidence of developing epilepsy.     

The Risk of Nonfebrile Seizures in Children Who Have Experienced Febrile Convulsions

Abstract: (1) The frequency of development of nonfebrile seizures in 116 children who had experienced at least one febrile convulsion and were followed for more than five to eight years was 4.3% (5 cases). Of these, three cases had prolonged generalized convulsions of the clonic or tonic-clonic type and two had brief generalized fits of the tonic-clonic type. (2) The risk factors identified as nonfebrile seizures after febrile convulsions were the preexisting neurological abnormality or developmental retardation, focal features and more than a 10-minute duration of the first febrile convulsions, and abnormal paroxysmal discharges at the initial interictal EEG recordings.     

Are brief febrile seizures benign? A systematic review and narrative synthesis

Febrile seizures affect 2%–5% of U.S. children and are considered benign although associated with an increased risk of epilepsy and, rarely, with sudden unexplained death. We compared rates of mortality, neurodevelopmental disorders, and neuropathology in young children with simple and complex febrile seizures to healthy controls. We systematically reviewed studies of 3- to 72-month-old children with simple or complex febrile seizures ≤30 min. We searched studies with outcome measures on mortality, neurodevelopment, or neuropathology through July 18, 2022. Bias risk was assessed per study design. Each outcome measure was stratified by study design. PROSPERO registration is CRD42022361645. Twenty-six studies met criteria reporting mortality (11), neurodevelopment (11), and neuropathology (13), including 2665 children with febrile seizures and 1206 seizure-free controls. Study designs varied: 15 cohort, 2 cross-sectional, 3 case–control, 5 series, and 1 case report. Mortality outcomes showed stark contrasts. Six cohort studies following children after febrile seizure (n = 1348) reported no deaths, whereas four child death series and 1 case report identified 24.1% (108/449) deaths associated with simple (n = 104) and complex (n = 3) febrile seizures ≤30 min. Minor hippocampal histopathological anomalies were common in sudden deaths with or without febrile seizure history. Most electroencephalography (EEG) studies were normal. Neuroimaging studies suggested increased right hippocampal volumes. When present, neurodevelopmental problems usually preexisted febrile-seizure onset. Risk bias was medium or high in 95% (18/19) of cohort and case–control studies vs medium to low across remaining study designs. Research on outcomes after simple or brief complex febrile seizures is limited. Cohort studies suffered from inadequate sample size, bias risk, and limited follow-up durations to make valid conclusions on mortality, neurodevelopment, and neuropathology. Sudden death registries, focused on a very small percentage of all cases, strongly suggest that simple febrile seizures are associated with increased mortality. Although most children with febrile seizures have favorable outcomes, longer-term prospective studies are needed.     

The Prevalence and Incidence of Convulsive Disorders in Children

Summary: Each year, about 150,000 children and adolescents in the United States will come to medical attention for evaluation of a newly occurring seizure disorder of some type. Between 2% and 4% of all children in Europe and the United States experience at least one convulsion associated with a febrile illness before the age of 5 years. The cumulative incidence of febrile convulsions among children ranges from about 1% in China to more than 8% in Japan and 14% in Guam. The peak incidence of a first febrile convulsion occurs in the second year of life. Between 0.5% and 1% of children and adolescents experience a seizure associated with other acute metabolic or neurologic insults; most of these occur in the neonatal period. The incidence of epilepsy (recurrent unprovoked seizures) in children and adolescents seems relatively consistent across all populations studied, ranging from 50 to 100/100,000. The highest incidence of epilepsy is in the first year of life. West syndrome accounts for about 2% of all childhood epilepsy, Lennox-Gastaut syndrome for 1–2%, childhood absence epilepsy (pyknolepsy) for 10–15%, juvenile myoclonic epilepsy for 5%, and idiopathic localization-related epilepsy for 10%. Between 0.5 and 1% of children experience a nonrecurrent, single, unprovoked convulsive episode. Following are the estimated numbers of children and adolescents with newly diagnosed convulsive disorders in the United States for the year 1990: febrile seizures, 100,000; neonatal seizures, 4,000; other provoked seizures, 6,000; single unprovoked seizures, 10,000; and epilepsy, 30,000.     

Febrile Seizures: Clinical Characteristics and Initial EEG

We examined the relationship between clinical characteristics and EEG classification in all children with febrile seizures examined at the University Pediatric Clinic, Skopje, Yugoslavia between 1982 and 1984. This is the only facility in Macedonia providing EEG or neurologic consultation for children. EEGs were classified as paroxysmally abnormal if they contained spikes, sharp waves, or spike-wave complexes considered abnormal for age. In all, 22% of the 676 children had an abnormal initial EEG. The most common basis for classification as abnormal was spike-wave complexes greater than 3 Hz; the next most common basis was the presence of spikes. Birth weight, gender, accompanying illness, and family history of seizures, and whether the index seizure was single or multiple were not associated with differences in rate of abnormal EEG. Clinically focal index seizures and longer duration were associated with EEG abnormality. Number of previous febrile seizures was associated with an increasing rate of EEG abnormality, from 18% in children with no previous seizures to 63% in those with four or more previous seizures. Age at EEG was linearly related to likelihood of paroxysmal EEG abnormality, both for the total cohort and for the 376 children with no previous seizures. In the total cohort, logistic regression identified leading predictors of abnormal initial EEG to be older age, number of previous febrile seizures, preexisting motor abnormality, and focal seizures. For children with a first febrile seizure, leading predictors were focal seizure, older age, and preexisting motor abnormality.     

The Prevalence and Incidence of Convulsive Disorders in Children

Summary: Each year, about 150,000 children and adolescents in the United States will come to medical attention for evaluation of a newly occurring seizure disorder of some type. Between 2% and 4% of all children in Europe and the United States experience at least one convulsion associated with a febrile illness before the age of 5 years. The cumulative incidence of febrile convulsions among children ranges from about 1% in China to more than 8% in Japan and 14% in Guam. The peak incidence of a first febrile convulsion occurs in the second year of life. Between 0.5% and 1% of children and adolescents experience a seizure associated with other acute metabolic or neurologic insults; most of these occur in the neonatal period. The incidence of epilepsy (recurrent unprovoked seizures) in children and adolescents seems relatively consistent across all populations studied, ranging from 50 to 100/100,000. The highest incidence of epilepsy is in the first year of life. West syndrome accounts for about 2% of all childhood epilepsy, Lennox-Gastaut syndrome for 1–2%, childhood absence epilepsy (pyknolepsy) for 10–15%, juvenile myoclonic epilepsy for 5%, and idiopathic localization-related epilepsy for 10%. Between 0.5 and 1% of children experience a nonrecurrent, single, unprovoked convulsive episode. Following are the estimated numbers of children and adolescents with newly diagnosed convulsive disorders in the United States for the year 1990: febrile seizures, 100,000; neonatal seizures, 4,000; other provoked seizures, 6,000; single unprovoked seizures, 10,000; and epilepsy, 30,000.     

Early clinical features and diagnosis of Dravet syndrome in 138 Chinese patients with SCN1A mutations

Objective: To summarize the early clinical features of Dravet syndrome (DS) patients with SCN1A gene mutations before the age of one. Methods: SCN1A gene mutation screening was performed by PCR–DNA sequencing and multiple ligation-dependent probe amplication (MLPA). The early clinical features of DS patients with SCN1A mutations were reviewed with attention to the seizures induced by fever and other precipitating factors before the first year of life. Results: The clinical data of 138 DS patients with SCN1A gene mutations were reviewed. The median seizure onset age was 5.3 months. Ninety-nine patients (71.7%) experienced seizures with duration more than 15 min in the first year of life. Two or more seizures induced by fever within 24 h or the same febrile illness were observed in 93 patients (67.4%). 111 patients (80.4%) had hemi-clonic and (or) focal seizures. Seizures had been triggered by fever of low degree (T < 38 °C) in 62.3% (86/138) before the first year of life. Vaccine-related seizures were observed in 34.8% (48/138). Seizures in 22.5% (31/138) of patients were triggered by hot bath. Carbamazepine, oxcarbazepine, lamotrigine, phenobarbital and phenytoin showed either no effect or exacerbating the seizures in our group. Conclusion: The seizure onset age in DS patients was earlier than that was in common febrile seizures. When a baby exhibits two or more features of complex febrile seizures in the first year of life, a diagnosis of DS should be considered, and SCN1A gene mutation screening should be performed as early as possible. Early diagnosis of DS will help clinicians more effectively prescribe antiepileptic drugs for stronger prognosis.     

Influenza A and febrile seizures in childhood

The aims of the present study are to identify predisposing factors of febrile seizures in influenza A infection and to clarify the special characteristics of febrile seizures in children with influenza A infection. Between January and July 2005, children hospitalized because of febrile seizures and subsequently confirmed influenza A infection were enrolled as subjects. Age-matched control subjects were those admitted as a result of influenza A infection but no febrile seizures (control 1) and children who developed febrile seizures with negative viral studies (control 2). Significant factors for the development of febrile seizures include: history of febrile seizures, family history of seizure disorders, and coexisting gastroenteritis. Independent risk factor for febrile seizures was history of febrile seizures (odds ratio 7.58, 95% confidence interval CI 1.48 to 38.84, P = 0.015). When compared with children who developed febrile seizures with negative virus studies, children who developed febrile seizures in influenza A infection had a significantly higher maximum body temperature, shorter duration of fever before seizure onset, and more frequent occurrence of partial seizures. Current episode represented first seizure in 26.5% of children infected with influenza A as compared with 50% of children whose virus studies were negative (P = 0.04). The findings suggest that effective vaccination may prevent development of febrile seizures, especially in those patients with past history of febrile seizures. Rapid diagnostic testing for influenza infection in the management of complex febrile seizures, especially during influenza season, is cost-effective.     

Is the long-term outcome of children following febrile convulsions favorable?

The study comprised 80 children aged 6 to 9 years with a history of febrile convulsions. A neurological examination, an interview to assess psychiatric anomalies, and a series of neuropsychological tests were performed on patients with previous febrile convulsions and on matched healthy controls. Children with non-febrile seizures or CNS infections were excluded. Recurrence of febrile seizures in the study group was 41% ( N =33), 18 children (22%) had prolonged febrile convulsions, six (7.5%) patients and two controls showed discrete neurological abnormalities. Behavioral anomalies were exhibited by 22% of the patients and 6% of the healthy children. The neuropsychological test results did not demonstrate significant differences between the children with febrile convulsions and the healthy controls. However, in children with prolonged febrile convulsions, non-verbal intelligence was found to be significantly lower as compared with children with simple febrile seizures and with controls. None of the other parameters tested yielded any differences between patients and controls. Children with multiple recurrences of febrile convulsions performed poorer in all tests when compared with children with only one febrile seizure or with controls. Other factors such as a positive family history of epilepsy, age at onset of febrile convulsions, or duration of the seizure were not found to be of prognostic significance.     

Surgical Treatment of Children with Medically Intractable Frontal or Temporal Lobe Epilepsy: Results and Highlights of 40 Years' Experience

Summary: Etiologic, pathologic, and clinical features of possible prognostic significance were studied in 118 children who underwent frontal or temporal lobe epilepsy surgery at the Montreal Neurological Institute (MNI) between 1940 and 1980 (excluding tumor cases). Mean age of seizure onset was 5.1 years (range 0–12 years), mean age at operation was 11.7 years (range 0.6–15 years), and median duration of follow-up was 15 years (range 2–31 years). Thirteen of 45 frontal surgery patients and 43 of 73 temporal surgery patients had an excellent outcome. In the frontal surgery group, this was restricted almost entirely to patients with an established etiology, particularly if this included a circumscribed resectable structural abnormality. In the temporal surgery group, a history of early, prolonged febrile seizures was usually associated with good outcome, unless there was additional evidence of extratemporal epilepsy. In the entire series, the presence of a nonresectable structural lesion or secondarily generalized seizures was associated with a poor outcome.     

Childhood-onset epilepsy with and without preceding febrile seizures

OBJECTIVE: To identify characteristics in children with epilepsy that differ between those who did versus did not have a history of preceding febrile seizures. BACKGROUND: Febrile seizures precede epilepsy in 10 to 15% of children. Little is known about the specific types of epilepsy associated with febrile seizures. METHODS: In a community-based, prospectively identified cohort of children, the association between prior febrile seizures and characteristics of the children's epilepsy (seizure type, epilepsy syndrome, age at onset, underlying etiology, family history) were examined for 524 of the children who were aged > or =1 year at onset of epilepsy. RESULTS: Seventy-three (13.9%) had febrile seizures. Children with febrile seizures were more likely to have a first-degree or a second-higher-degree relative with febrile seizures and less likely to have childhood absence epilepsy and absence seizures compared with children without febrile seizures. This was especially true for simple febrile seizures. There was no specific association with localization-related forms of epilepsy. Complex, but not simple, febrile seizures were associated with younger age at onset of epilepsy. There was no evidence that focal or prolonged febrile seizures were associated with localization-related epilepsy or temporal lobe epilepsy per se. Of the three children whose initial MRIs demonstrated hippocampal atrophy, none had a history of febrile seizures. CONCLUSIONS: At the time of diagnosis, febrile seizures are not specifically related to temporal lobe epilepsy or localization-related epilepsy in general. A genetic component for febrile seizures is suggested by its positive associations with family history, especially for simple febrile seizures. Complex febrile seizures represent an underlying age-dependent susceptibility.     

Occipital seizures induced by Intermittent Photic Stimulation in Dravet syndrome

PurposeDravet syndrome (DS) is a rare disorder with seizure onset in the first year of life, typically beginning with prolonged febrile hemiclonic seizures or generalized tonic–clonic seizures. Photosensitivity is reported in more than 40% of patients. We present two cases of DS in which we had the chance to record occipital seizures induced by Intermittent Photic Stimulation (IPS).MethodWe retrospectively reviewed the medical records of 32 children affected by DS. All clinical notes were reviewed in order to evaluate the occurrence of seizures induced by IPS.ResultsAmong the 32 reviewed clinical records, two patients with IPS-induced seizures were found. In both patients seizures originated from the occipital-temporal region. Clinical history was characterized by generalized tonic–clonic seizures, and myoclonia. At the age respectively of 11 months and 20 months they presented a prolonged focal seizure induced by IPS at a frequency of 10 Hz. During the follow-up they additionally presented with hypomotor seizures, also induced by IPS during laboratory EEG examinations. The semiology of hypomotor seizures resembled what is described as “complex partial status”, a type of non-convulsive status with ictal discharges arising unilaterally from the occipito-temporal region.ConclusionBased on available literature, IPS induced occipital seizures have not been reported during the first year of life. Although pathophysiological features are not yet completely understood, both photosensitivity and occipital seizures should be considered in the diagnostic evaluation in DS. The documentation of IPS induced occipital seizures might contribute to widen the clinical and neurophysiological spectra of DS.     

Clinical Profile of Partial Seizures Beginning at Less Than Four Years of Age

Clinical features of all our 46 patients whose recurrent partial seizures began at age less than or equal to 47 months were studied. Thirty-seven (80%) had motor seizures which were exclusively unilateral in 14 patients, bilaterally synchronous in 8, and both unilateral and bilaterally synchronous in 15. Thirty-three patients (72%) had complex partial seizures (CPS), and 11 patients (24%) had simple partial somatosensory seizures. Clinical seizures were recorded by EEG in 18 patients (39%), and a subclinical (larval) seizure was recorded in 1; those in 10 patients arose from a temporal lobe, 4 were from a frontal lobe, and in 5 they involved two adjacent lobes from onset. Several extra-ictal features reliably indicated lobe or hemisphere of seizure onset. The lobe of principal interictal EEG spikes corresponded to seizure origin in 33 of 34 patients (97%), and regional delta activity corresponded to lobe of seizure origin in 22 of 24 patients (92%). The seizures of all 13 patients with unilateral neurologic signs corresponded to the hemisphere implicated by the deficit. Computed tomography (CT) scan showed lesions in 30 patients (65%) and corresponded to the lobe of seizure onset in 27 of the 30 (90%). Seizures arose primarily from a frontal lobe in 22 of 46 patients (48%), from a temporal lobe in 14 patients (30%), and from an occipital-parietal-posterotemporal region in 6 patients (13%); only the hemisphere of origin could be determined in 4 patients. Cortical developmental abnormalities were the most common known cause (12 patients, 26%); febrile seizures and primary brain tumors occurred in 10 and 8 patients, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)