Utility of an immunotherapy trial in evaluating patients with presumed autoimmune epilepsy.

OBJECTIVE: To evaluate a trial of immunotherapy as an aid to diagnosis in suspected autoimmune epilepsy. METHOD: We reviewed the charts of 110 patients seen at our autoimmune neurology clinic with seizures as a chief complaint. Twenty-nine patients met the following inclusion criteria: (1) autoimmune epilepsy suspected based on the presence of ≥ 1 neural autoantibody (n = 23), personal or family history or physical stigmata of autoimmunity, and frequent or medically intractable seizures; and (2) initiated a 6- to 12-week trial of IV methylprednisolone (IVMP), IV immune globulin (IVIg), or both. Patients were defined as responders if there was a 50% or greater reduction in seizure frequency. RESULTS: Eighteen patients (62%) responded, of whom 10 (34%) became seizure-free; 52% improved with the first agent. Of those receiving a second agent after not responding to the first, 43% improved. A favorable response correlated with shorter interval between symptom onset and treatment initiation (median 9.5 vs 22 months; p = 0.048). Responders included 14/16 (87.5%) patients with antibodies to plasma membrane antigens, 2/6 (33%) patients seropositive for glutamic acid decarboxylase 65 antibodies, and 2/6 (33%) patients without detectable antibodies. Of 13 responders followed for more than 6 months after initiating long-term oral immunosuppression, response was sustained in 11 (85%). CONCLUSIONS: These retrospective findings justify consideration of a trial of immunotherapy in patients with suspected autoimmune epilepsy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that in patients with suspected autoimmune epilepsy, IVMP, IVIg, or both improve seizure control.

De novo SCN1A mutations in migrating partial seizures of infancy.

OBJECTIVE: To determine the genetic etiology of the severe early infantile onset syndrome of malignant migrating partial seizures of infancy (MPSI). METHODS: Fifteen unrelated children with MPSI were screened for mutations in genes associated with infantile epileptic encephalopathies: SCN1A, CDKL5, STXBP1, PCDH19, and POLG. Microarray studies were performed to identify copy number variations. RESULTS: One patient had a de novo SCN1A missense mutation p.R862G that affects the voltage sensor segment of SCN1A. A second patient had a de novo 11.06 Mb deletion of chromosome 2q24.2q31.1 encompassing more than 40 genes that included SCN1A. Screening of CDKL5 (13/15 patients), STXBP1 (13/15), PCDH19 (9/11 females), and the 3 common European mutations of POLG (11/15) was negative. Pathogenic copy number variations were not detected in 11/12 cases. CONCLUSION: Epilepsies associated with SCN1A mutations range in severity from febrile seizures to severe epileptic encephalopathies including Dravet syndrome and severe infantile multifocal epilepsy. MPSI is now the most severe SCN1A phenotype described to date. While not a common cause of MPSI, SCN1A screening should now be considered in patients with this devastating epileptic encephalopathy.

Comorbidities in pediatric epilepsy: beyond "just'' treating the seizures.

The goal of this review is to discuss the comorbidities reported in specific epilepsy syndromes to examine possible underlying causes or associations and to present data on current therapies for these conditions. Comorbid conditions including cognitive impairment, neuropsychiatric problems, and social difficulties are common in children with epilepsy, and often more disabling than the seizures themselves. Biological factors associated with a greater risk of comorbidity in epilepsy include younger age at seizure onset, cognitive impairment, temporal or frontal lobe onset, and intractability. Social factors correlating with greater risk include lower socioeconomic status, lower parental education level, and poorer family function. These comorbid conditions not only have a significant impact on the child but also are a source of increased stress and burden for families. Increased awareness and early diagnosis of these conditions may affect therapeutic intervention and long-term outcome as well as assist in better understanding of potential risk factors and biological mechanisms.

Seizure response dogs: evaluation of a formal training program.

Evidence supporting seizure-related behaviors in dogs is emerging. The methods of seizure response dog (SRD) training programs are unstudied. A standardized survey was retrospectively applied to graduates of a large SRD program. Subjective changes in quality of life (QOL) parameters were explored. Data were captured on animal characteristics, training methods, response and alerting behaviors, effects on seizure frequency, and accuracy of epilepsy diagnosis. Twenty-two patients (88%) participated (median age=34, range=12-66, 73% female). Most had childhood-onset epilepsy (87%) that was refractory with averages of 36 seizures/month and 4.8 medications failed. All had neurologist-confirmed epilepsy, most being symptomatic partial (64%). SRD behaviors were reliable, including emergency response system activation in 27%. All reported SRD-related QOL improvements (major 82%, moderate 18%) across multiple parameters. Spontaneous alerting behavior developed in 59%. That SRD programs may select genuine epilepsy patients, instill valuable assistance skills, and generate meaningful QOL improvements supports further seizure dog research.

Acute glomerulonephritis presenting with PRES: a report of 4 cases.

OBJECTIVE: Posterior reversible encephalopathy syndrome (PRES) occurs most commonly in the setting of known hypertension or use of immunosuppressive agents. DESIGN AND METHODS: We report four previously-well children who presented acutely with altered mentation, seizures and visual disturbances and were diagnosed with PRES. RESULTS: Only one child had a history of gross hematuria prior to the seizure. All four were discovered to be hypertensive only after onset of their neurological symptoms, and were subsequently diagnosed with glomerulonephritis. All four had rapid resolution of neurological symptoms with adequate treatment of hypertension. CONCLUSIONS: Blood pressure must be measured promptly in all children presenting with these symptoms. If elevated, the diagnosis of PRES should be strongly considered and a workup for renal disease pursued.

Diagnostic inaccuracy in children referred with "first seizure": role for a first seizure clinic.

PURPOSE: To determine (a) the range of diagnoses, and (b) the prevalence of previous seizures in children presenting to a first seizure clinic. METHODS: One hundred twenty-seven children were seen in a tertiary care First Seizure Clinic. Inclusion criteria were age 1 month-17 years with an unprovoked event suggestive of seizure. Data collected included referring physician specialty, child's age, gender, developmental status, and clinical diagnosis of epileptologist (nonepileptic vs. epileptic). For those with epileptic events, seizure type, syndrome (if identifiable), presumed etiology (idiopathic, cryptogenic, and symptomatic), presence of prior afebrile and febrile seizures, provoking factors, family history, pre/perinatal complications and EEG results were recorded. RESULTS: The diagnosis was epileptic in 94 (74%), nonepileptic in 31 (24%) and unclassifiable in two (2%). Pediatricians were more likely to refer true epileptic events (92%) than ED physicians (76%) or family physicians (65%). Mean age at presentation was 8 years. Fifteen percent of children were developmentally delayed and neurological examination was abnormal in 11%. For those diagnosed with epileptic events, 32 presented with generalized while 62 presented with partial onset seizures. An epilepsy syndrome was identifiable in 15 cases. Thirty-eight percent experienced a prior probable seizure which was recognized by the referring physician in only one case. An EEG was done in all children with seizures and was abnormal in 41%. Early EEG was performed in 20% of children and did not show statistical significance. CONCLUSIONS: Diagnostic inaccuracy is common in first seizure. One quarter of children were incorrectly diagnosed as having a seizure while the diagnosis of epilepsy was missed in over one-third of children.

Prolonged seizures exacerbate perinatal hypoxic-ischemic brain damage.

This study was undertaken to clarify whether seizures in the newborn cause damage to the healthy brain and, more specifically, to determine the extent to which seizures may contribute to the brain-damaging effects of hypoxia-ischemia (HI). Seizures were induced in 10-d-old rat pups with kainic acid (KA). Seizure duration was determined electrographically. HI was induced by common carotid artery ligation followed by exposure to 8% oxygen for either 15 or 30 min. Six groups of animals were assessed: 1) controls [neither KA nor HI (group I)]; 2) group II, KA alone; 3) group III, 15 min HI alone; 4) group IV,15 min HI plus KA; 5) group V, 30 min HI alone; and 6) group VI, 30 min HI plus KA. Animals were assessed neuropathologically at 3 (early) and 20 (late) d of recovery. KA injection without hypoxia resulted in continuous clinical and electrographic seizures lasting a mean of 282 min. No neuropathologic injury was seen in groups I (no HI or KA), II (KA alone), III (15 min HI alone), or IV (15 min HI and KA). Animals in group V (30 min HI alone) displayed brain damage with a mean score of 2.3 and 0.60 at 3 and 20 d of recovery, respectively. Animals in group VI (30 min HI and KA) had a mean score of 12.1 and 3.65 at 3 and 20 d of recovery, respectively. Compared with group V, the increased damage as a result of the seizure activity in group VI occurred exclusively in the hippocampus. Status epilepticus in the otherwise "healthy" neonatal brain does not cause neuropathologic injury. However, seizures superimposed on HI significantly exacerbate brain injury in a topographically specific manner.

Prognostic significance of failure of the initial antiepileptic drug in children with absence epilepsy.

PURPOSE: In children with childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE), to determine the impact of failure of initial antiepileptic drug (AED) for lack of efficacy in eventual seizure control and long-term remission of epilepsy. METHODS: Centralized EEG records for the province of Nova Scotia allowed identification of all children seen with CAE or JAE between 1977 and 1985. Information regarding success or failure of initial AED in fully controlling seizures and long-term seizure control and remission of epilepsy was collected by patient questionnaire and chart review. RESULTS: Eighty-six of 92 eligible patients were followed up (75 CAE, 11 JAE). Initial AED treatment was successful in 52 (60%) of 86. Success tended to be greater for valproate (VPA) than for other AEDs (p = 0.07), and lower if generalized tonic-clonic or myoclonic seizures coexisted (p < 0.004 and p < 0.03). Terminal remission was more likely if the initial AED was successful than if it had failed (69% vs. 41%; p < 0.02). Compared with those in whom the initial AED was successful, subjects whose initial AED had failed were more likely to progress to juvenile myoclonic epilepsy (JME) at last follow-up (32% vs. 10%; p < 0.02) and to develop intractable epilepsy (17% vs. 2%; p < 0.04). CONCLUSIONS: Initial AED was successful in 60% of children with AE. If the first AED failed, the outcome was less favorable, with a lower rate of terminal remission and a higher rate of progression to JME and intractable epilepsy.

Do cognitively normal children with epilepsy have a higher rate of injury than their nonepileptic peers?

The objective of this study was to determine if cognitively normal children with epilepsy have higher accidental injury rates than their age- and sex-matched friends without epilepsy and what factors may predict this. Patients 5 to 16 years old, with a developmental quotient >70, without major motor or sensory impairments, with a 1-year history of epilepsy and who either had a seizure or had been on antiepileptic drugs within the past year, were identified from the pediatric neurology database of the Royal University Hospital. Twenty-five of 31 cases and their best friend controls agreed to participate. Seizure-related factors including type, duration, frequency, timing, date of diagnosis, antiepileptic drug initiation and discontinuation, and specific types and total antiepileptic drugs used were assessed by interview. Questionnaires about accidental injury including type, number, severity, and, if applicable, injuries resulting from seizures, as well as general safety practices, activity restrictions, and presence of attention-deficit hyperactivity disorder, were completed by cases and controls. No significant differences in injury numbers (specific types or total) or severity were found, although a small number of epileptic children were very predisposed to injury. Seizure-related factors did not predict injury in cases. Safety practices were similar, and restrictions in cases were not excessive. Children with attention-deficit hyperactivity disorder had a higher injury rate, both in cases and controls. Cognitively normal children with epilepsy do not have a higher injury rate than their nonepileptic peers. If consciousness is impaired in seizures, extra supervision for swimming and bathing and restricted climbing heights are suggested. All other safety restrictions for epileptic children should follow those appropriate to nonepileptic children to allow a normal lifestyle.

Parental anxiety and family disruption following a first febrile seizure in childhood.

OBJECTIVE: To evaluate the degree of parental anxiety and family disruption following a child's first febrile seizure. PATIENTS AND METHODS: The families of all children presenting with their first febrile seizure to any of the three emergency departments in the Saskatoon District, Saskatchewan, were invited to participate in a telephone interview to assess the degree of parental anxiety and family dysfunction that was experienced. Parameters measured included co-sleeping with the child, parental sleep disturbance, parental fatigue, monitor use, the number of night time checks on a child, child care use, parental outings, parental fear of missing a seizure, parental perception of a child's increased vulnerability and the family's stress level. The interview, which was conducted shortly after presentation at the emergency departments, compared anxiety and dysfunction experienced during the two weeks immediately preceding the visit with that experienced during the two weeks following a febrile seizure. Potential predictors of anxiety and dysfunction, including details of the presenting seizure, past medical illnesses, family history, the family's socioeconomic status and parental perception of the risk of a febrile seizure were queried. RESULTS: Thirty-one (89%) of 35 families who were eligible for the study participated. Parental anxiety and family dysfunction were significantly greater for nearly all of the parameters assessed during the two weeks following a seizure. Socioeconomic factors correlated most closely with anxiety and dysfunction before a febrile seizure; however, socioeconomic factors were less predictive of anxiety and dysfunction during the two weeks following a seizure. CONCLUSIONS: Parental anxiety and family dysfunction are the rule following a child's first febrile seizure. Neither higher socioeconomic status nor an understanding of the low risk of sequelae associated with febrile seizures was strongly predictive of improved coping during the two weeks following a seizure.

Prognosis of seizures occurring in the first year.

To determine whether predictors of neurodevelopmental outcome and the course of epilepsy can be identified in infants 1-12 months of age presenting with their first afebrile seizure, we collected demographic data, seizure details (type, frequency, duration, etiology, and treatment), developmental status, neurologic findings at presentation and follow-up, and electroencephalographic (EEG), neuroimaging, metabolic, hematologic, and chemistry test results by chart review, parental interview, and neurologic examination in 40/41 subjects (98%) presenting to our institution between January 1994 and December 1998. The mean duration of follow-up from onset of seizures was 29 months (S.D. = 17; range = 1-64). Predictors of developmental and neurologic abnormalities at follow-up included developmental delay and abnormal neurologic examination at presentation, infantile spasms, lack of response to antiepileptic drugs (AEDs), valproate use, and abnormal EEG or neuroimaging results. Predictors against seizure control and epilepsy remission and for the development of problematic seizures at follow-up included valproate use and lack of response to AEDs. Poor neurodevelopmental outcome of children with new-onset afebrile seizures in the first 1-12 months of age can be accurately predicted at diagnosis with the aid of EEG and neuroimaging studies. The course of epilepsy is more difficult to predict, but failure to respond to the first AED is worrisome.

Does status epilepticus in children cause developmental deterioration and exacerbation of epilepsy?

The aims of this study were to determine predictors of abnormal outcome, neurodevelopmental deterioration, new-onset epilepsy, refractory epilepsy, and recurrent status epilepticus in children presenting with status epilepticus. For all children presenting to Royal University Hospital, Saskatoon, Saskatchewan, Canada, with status epilepticus between January 1987 and December 1996, demographic data, details of status epilepticus (etiology, duration, treatment, and investigations), developmental milestones, seizures prior to and following status epilepticus, recurrent status epilepticus, and neurologic examination findings at status epilepticus and at follow-up were collected by chart review, patient interview, and neurologic examination. Neurodevelopmental outcome was determined for all subjects except those who died during the initial hospitalization. Predictors of new-onset epilepsy, refractory epilepsy, and recurrent status epilepticus were determined for children followed for 3 months or more after status epilepticus. At follow-up, 79% were abnormal neurologically. Predictors included etiology (nonfebrile or nonidiopathic), perinatal difficulties, preceding developmental delay, abnormal initial neurologic examination; and abnormal neuroimaging. Thirty-four percent showed neurodevelopmental deterioration; predictors included etiology (nonidiopathic or nonfebrile), young age at status epilepticus (12 months or less), and abnormal neuroimaging. Thirty-six percent with no history of seizures preceding status epilepticus developed epilepsy and 25% developed refractory epilepsy. Fifty percent of children had recurrent status epilepticus. In conclusion, very few children presenting in status epilepticus were normal at follow-up. Sequelae were seen predominantly in those with a nonidiopathic, nonfebrile etiology, whereas those with idiopathic or febrile status epilepticus did well.

Seizures in the elderly: etiology and prognosis.

PURPOSE: To determine the etiology, early mortality, predictors of prognosis and diagnostic yields of EEG and CT scans of the head in new-onset seizures in elderly patients. METHODS: EEG records for the north-central region of Saskatchewan, between 01/94 and 12/95 were reviewed to identify all adults aged 60 years or older with new-onset seizures. Information on demographics, seizure type, etiology, EEG and neuroimaging studies, anti-epileptic treatment and course of epilepsy was obtained by review of medical records and interview with the patient and/or family member. RESULTS: Of 88 eligible subjects, 61 (69%) were contacted for follow-up, 19 (22%) were deceased (12 of whom who had a serious underlying etiology to their seizures, which was obvious at the time of initial presentation and led shortly to their demise), 4 (5%) were lost to follow-up and 4 (5%) refused participation. Excluding those refusing participation, 74/84 (88%) patients presented with partial or secondarily generalized seizures. Seizures were cryptogenic in 38/84 (45%), and due to stroke in 19/84 (23%). EEGs were abnormal in 61/84 (73%) cases, with epileptiform discharge in 33/84 (39%). CT scans were abnormal in 57/84 (68%) cases with acute pathology in 29/84 (35%). Of the 61 patients participating in the follow-up interview, 54 (89%) were treated with anti-epileptic medication and seizure control was usually successful. Predictors for ongoing seizures were more than 3 seizures at presentation, epileptiform activity on initial EEG and discontinuation of anti-epileptic medication for lack of efficacy. CONCLUSION: Prognosis of new-onset seizures in elderly patients is favorable if seizures are not symptomatic of a life-threatening disorder.

Benign epilepsy of childhood with centrotemporal spikes.

Benign epilepsy of childhood with centrotemporal spikes (BECT) is the most common partial epilepsy syndrome in the pediatric age group, with an onset between age 3 and 13 years. The typical presentation is a partial seizure with parasthesias and tonic or clonic activity of the lower face associated with drooling and dysarthria. Seizures commonly occur at night and may become secondarily generalized. They are usually infrequent and may not require antiepileptic drugs but, if treated, they tend to be easily controlled. Children with BECT are neurologically and cognitively normal. The EEG shows characteristic high-voltage sharp waves in the centrotemporal regions, which are activated with drowsiness and sleep. In this typical form, BECT is easily recognized. However, atypical cases are common and the definition of BECT can become blurred. Although further investigations are not required in cases with typical clinical and EEG findings and normal neurologic examinations, neuroimaging studies may be required in atypical cases to rule out other pathology. The long-term medical and psychosocial prognosis of BECT is excellent, with essentially all children entering long-term remission by mid-adolescence.

Long-term psychosocial outcome in typical absence epilepsy. Sometimes a wolf in sheeps' clothing.

OBJECTIVES: To determine whether young adults in whom typical absence epilepsy has been diagnosed in childhood have greater psychosocial difficulties than those with a non-neurologic chronic disease and to decide which seizure-related factors predict poor psychosocial outcome. DESIGN: Population-based, inception cohort study. SETTING: The only tertiary care pediatric hospital in the province of Nova Scotia. PATIENTS: All children in whom typical absence epilepsy or juvenile rheumatoid arthritis (JRA) was diagnosed between January 1, 1997, and December 31, 1985, who were aged 18 years or older at follow-up in March 1994 to April 1995. Patients with typical absence epilepsy were identified from centralized electroencephalographic records for Nova Scotia, and those with JRA were identified from discharge diagnoses from the only children's hospital in Nova Scotia. MAIN OUTCOME MEASURE: Patients participated in a structured interview that assessed psychosocial function. RESULTS: Fifty-six (86%) of the 65 patients with absence epilepsy and 61 (80%) of the 76 patients with JRA participated in the interview. The mean age of the patients at the interview was 23 years. Terminal remission occurred in 32 (57%) of the patients with typical absence epilepsy but in only 17 (28%) of the patients with JRA. Factor analysis identified 5 categories of outcome: academic-personal, behavioral, employment-financial, family relations, and social-personal relations. Patients with typical absence epilepsy had greater difficulties in the academic-personal and in the behavioral categories (P < .001) than those with JRA. Those with ongoing seizures had the least favorable outcome. Most seizure-related factors showed minimal correlation with psychosocial functioning. CONCLUSION: Young adults with a history of typical absence epilepsy, particularly those without remission of their seizures, often have poor psychosocial outcomes, considerably worse than those with JRA.

Long-term prognosis of typical childhood absence epilepsy: remission or progression to juvenile myoclonic epilepsy.

OBJECTIVE: To determine the proportion and characteristics of children presenting with childhood absence epilepsy (CAE) who were not taking anti-epileptic drugs (AEDs) and were seizure-free over the last year of long-term follow-up. METHODS: For case finding, centralized EEG records for the province of Nova Scotia allowed identification of all children with typical CAE diagnosed between 1977 and 1985. Follow-up was done in 1994 to 1995. RESULTS: Of 81 children with CAE, 72 (89%) were contacted for follow-up. Mean age at seizure onset was 5.7 years (range, 1 to 14 years) and at follow-up was 20.4 years (range, 12 to 31 years). Forty-seven (65%) were in remission. Twelve others (17%) were not taking AEDs but continued to have seizures. Thirteen (18%) were taking AEDs; five were seizure-free over the last year (in four of these a trial without AEDs had previously failed). Fifteen percent of the total cohort had progressed to juvenile myoclonic epilepsy (JME). Multiple clinical and EEG factors were examined as predictors of outcome. Factors predicting no remission (p < 0.05) included cognitive difficulties at diagnosis, absence status prior to or during AED treatment, development of generalized tonic clonic or myoclonic seizures after onset of AEDs, abnormal background on initial EEG, and family history of generalized seizures in first-degree relatives. CONCLUSIONS: Only 65% of children presenting with CAE had remission of their epilepsy. Forty-four percent of those without remission had developed JME. At the time of diagnosis, remission is difficult to predict accurately in most patients. However, development of generalized tonic-clonic seizures or myoclonic seizures during AED treatment is ominous, predicting both lack of remission of CAE and progression to JME.

Accidental injury is a serious risk in children with typical absence epilepsy.

OBJECTIVES: To determine if young adults with a history of typical absence epilepsy (AE) in childhood have a greater risk of accidental injury than controls with juvenile rheumatoid arthritis (JRA). To assess the nature and severity of these injuries. METHODS: All patients with AE or JRA diagnosed between 1977 and 1985, who were 18 years or older at the onset of the study, were identified from review of pediatric electroencephalographic records for the province of Nova Scotia (AE) or review of the medical records database at the only tertiary care pediatric center for the province (JRA). Fifty-nine (86%) of 69 patients with AE and 61 (80%) of 76 patients with JRA participated in an interview in 1994 or 1995, assessing nature, severity, and treatment of prior accidental injuries. Patients with AE were further questioned about injuries sustained during an absence seizure. RESULTS: Sixteen (27%) of 59 patients with AE reported accidental injury during an absence seizure, with risk of injury being 9% per person-year of AE. Most injuries (81%) occurred during anti-epileptic drug therapy. Although the majority of injuries did not require treatment, 2 (13%) of 16 patients required minor treatment and 2 (13%) of 16 were admitted to hospital. The risk of accidental injury resulting from an absence seizure in person-years at risk was highest in juvenile myoclonic epilepsy (45%), moderate in juvenile AE (14%), and lowest in childhood AE (3%). Patients with AE had a greater number of overall accidental injuries than those with JRA (P<.04), but these differences were particularly marked for bicycle (P<.003) and car accidents (P<.05) and for mild head injuries (P=.05). CONCLUSIONS: Accidental injury is common in AE and usually occurs after anti-epileptic drug treatment is started. Injury prevention counseling is indicated both at diagnosis and follow-up. Bicycle accidents pose a special risk and helmet use should be mandatory.

Will a critical level of hyperventilation-induced hypocapnia always induce an absence seizure?

We wished to determine if the degree of hypocapnia correlates with increased frequency of absence seizures and if there is a critical pCO2 at which absence seizures are reliably provoked. Twelve untreated children with newly diagnosed absence epilepsy were continuously monitored by EEG and end-expiratory CO2 recording during quiet respiration and hyperventilation (to absence seizure or exhaustion) while breathing four gas mixtures: (a) room air, (b) 100% O2, (c) 4% CO2 in room air, or (d) 4% CO2 + 96% O2). In quiet respiration, a reduction in number of spike and wave bursts and total seconds of spike and wave was noted in children breathing supplemental CO2 (gases c and d vs. gases a and b), p < 0.05. Supplemental O2 had no effect. Eight subjects had absence seizures elicited with each trial of hyperventilation. All subjects had their own critical pCO2, ranging from 19 to 28 mmHg. Three children had no seizures, two despite hypocapnia to pCO2 of 19 and 21 and 1 who achieved a pCO2 of only 25. In 1, absence seizures were provoked in only six of nine hyperventilation trials to pCO2 of 17-23. In 67% of subjects, absence seizures were reliably provoked by hypocapnia. Critical pCO2 varied among children with absence. Determination of whether variation in sensitivity to hypocapnia may be helpful in determining response to antiepileptic drugs (AEDs) or remission of seizures will require further study.

Incidence of epilepsy in childhood and adolescence: a population-based study in Nova Scotia from 1977 to 1985.

Data from a regional EEG laboratory allowed us to identify almost all children in Nova Scotia (population 85,000) with one or more unprovoked, afebrile seizures from 1977 through 1985. We then reviewed hospital and pediatric neurology physician charts to limit cases to those with two or more definite afebrile seizures between the ages of 1 month and 16 years. In all, 693 children developed epilepsy: typical childhood absence seizures (AS) (97), either generalized tonic-clonic (GTCs) or partial seizures either secondarily generalized or not (511), and other generalized seizure types, including infantile spasms (IS) as well as myoclonic, akinetic, tonic, and atypical AS (85). The incidence of epilepsy was 118 in 100,000 for children aged less than 1 year, 48 in 100,000 for those aged 1-5 years, 43 in 100,000 for those aged 6-10 years, and 21 in 100,000 for those aged 11-15 years. The incidence for each year of age between 1 and 10 years was remarkably constant (mean 46 in 100,000 +/- 7 SD). Comparison of the incidence rates showed significant differences for those aged less than one year as compared with all others, and for those aged greater than 10 years as compared with those aged 1-10 years. We conclude that the incidence of epilepsy is highest in the first year of life, plateaus in early childhood, and decreases markedly after age 10 years. The overall incidence of epilepsy in childhood is lower than that reported in previous studies.