epidemiology
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Diagnosis and Treatment of Epilepsy
Module III. Epidemiology
by Edwin Trevathan, M.D., M.P.H.
Director, Pediatric Epilepsy CenterSt. Louis Children’s Hospital
Washington University School of Medicine and
W. Edwin Dodson, M.D.
Developed with an unrestricted educational grant from Janssen-Cilag
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Objectives __________________________________________
Be aware of the effects of age and economic development on the incidence and prevalence of epilepsy.
Know how etiology varies with age of onset of seizures and epilepsy.
Know the conditions that are often associated with epilepsy.
Recognize that a majority of cases of epilepsy remit spontaneously.
Recognize risk factors for intractability.
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Age of Epilepsy Onset in Atlanta Children (Murphy & Trevathan, Epilepsia 1995;36:866-72)
39.5%
8.2% 7.2% 5% 5.8% 6% 8.6% 7.6% 7.8% 4.4%
0
5
10
15
20
25
30
35
40
1Yrs
2Yrs
3Yrs
4Yrs
5Yrs
6Yrs
7Yrs
8Yrs
9Yrs
10Yrs
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CAUSES OF EPILEPSY________________________________
Primary 77% idiopathic or cryptogenic
Symptomatic 23%
5% Cerebrovascular
4% CNS Neoplasm
4% Congenital CNS Malformation
4% Trauma
3% CNS Infection
2% Other known (Metabolic & Toxic)
1% Birth Asphyxia
Hauser WA & Hesdorfer DC, 1990.
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Seizure Types Among Atlanta Children with Epilepsy
___________________________________________
Generalized 35% (n=187)
Tonic 2%
Tonic-clonic 21%
Myoclonic 3%
Atonic 1%
Absence 5%
Infantile spasms 1%
Partial 58% (n=311)
Simple Partial 2%
Complex Partial 30%
Secondary gen 23%
Unclassified 7%
Murphy CC et al., J Pediatr 1995;123:513-20
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Seizures and Epilepsy in Children
Benign syndrom esNo lon g -term n eu rolog ical care
Seizures controlled w ith m eds'rou tin e' ep ilep sy care
Intractable Epilepsy1/3 of ch ild h ood ep ilep sy
m ajority of costsh ig h m orb id ity & m ortality
EpilepsyPrevalen ce ab ou t 1% of ch ild ren
First Seizure or ? Seizure> 100 p er 100,000 p er year
P revalen ce > 5%
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Prevalence of Epilepsy in the General Population____________________________________________
In developed countries, the prevalence of active epilepsy is
5 to 8 per 1000 children.
approximately 6 per 1000 adults.
In developing countries, the prevalence is much higher. For example, in rural Honduras the prevalence is
23 per 1000.
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Basic Epidemiology of Epilepsy______________________________________
Overall prevalence is 7 per 1000.
Incidence in childhood is 100 per 100,000 children per year.
More than 50% of people with epilepsy have partial seizures.
An estimated 60-70% of people respond to antiepileptic medications and become seizure free.
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Basic Epidemiology of Epilepsy______________________________________
An estimated 60-70% of people respond to antiepileptic medications and become seizure free.
If a person fails to be controlled with 3 antiepileptic drugs, the prognosis for control with medication is poor.
The average duration of intractable epilepsy among adults referred for epilepsy surgery is 22 years.
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Basic Epidemiology of Febrile Seizures________________________________________
Lifetime prevalence is 20 to 150 per 1000
66% of those affected have only one.
By age 7 years, epilepsy develops in 3% of children who had febrile seizures and in 0.7% of all children.
15% of people with epilepsy have a history of febrile seizures.
Some forms of febrile seizures have Mendelian inheritance.
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Febrile Seizures andRisk Factors for Later Epilepsy
__________________________________
Brief duration of fever before initial FS (<1 hour)
Complex FS (partial epilepsy)
Partial
Prolonged (10 min) or
Multiple per 24 hrs
Neurological or developmental abnormalities
Family history of epilepsy
Three or more seizures
Specific genetic epileptic disorders
Nelson & Ellenberg, 1978; Annegers et al, 1987; Berg & Shinnar, 1996
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Risk Factors for Intractable Epilepsy in Childhood_____________________________________________
Risk Factor Odds Ratio for Intractability
Early Onset Epilepsy Infantile Spasms 23.36 Microcephaly 9.62 Status Epilepticus 4.48 Remote Symptomatic Diagnosis 4.33 Neonatal Sz 3.76 Myoclonic & Atonic Sz 4.13 Prior FS 0.94
Berg AT et al. Epilepsia 1996;37:24-30.
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Comorbidities of Epilepsy_________________________________
Epilepsy is more likely to occur in people who have other neurological abnormalities.
In these instances the underlying brain disease manifests itself through the comorbid conditions independently. epilepsy cerebral palsy mental retardation
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Developmental Disabilities Among Atlanta Children with Epilepsy
_________________________________________
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
All Epilepsy Generalized Partial Unclassified
MRCPBlindDeaf
Murphy et al. J Pediatric 1995;123:513-20.
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Developmental Brain
Insults
Cerebral Palsy
Epilepsy
Mental Retardation
Independent Comorbidities
© Dodson, 2000
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CP
MR
EpilepsyEpilepsy
© Dodson, 2000
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CP
9%
MR9%
EpilepsyEpilepsy
© Dodson, 2000
20
CP
9%
33%
MR9%
15%
EpilepsyEpilepsy
© Dodson, 2000
21
CP
9%
33%
MR9%
15%
20%
EpilepsyEpilepsy
© Dodson, 2000
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CP
MR68%68%
EpilepsyEpilepsy
© Dodson, 2000
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Response to AEDs among children with partial seizures
1st AED
60-70%Respond
2ndAED
30-40%Respond
3rdAED
10-15%Respond
The average duration of intractable seizuresamong adults referred to epilepsy centers
in the U.S.A. is 22 years.
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Intractable Epilepsy__________________________________
Definition: Failure to achieve seizure freedom without medication side effects
In syndromes that should have a benign prognosis but fail to respond to drug therapy, question the diagnosis.
Benign Rolandic Epilepsy
Childhood Absence Epilepsy
Benign Occipital Epilepsy
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Intractable Childhood Epilepsies__________________________________
Localization-related
Temporal lobe epilepsy
Mesial temporal
Neocortical temporal
Extra-temporal epilepsies
Lesional
Non-lesional
Generalized epilepsies
Lennox-Gastaut syndrome
Infantile spasms
Severe myoclonic epilepsy of infancy (SMEI)
Acquired epileptic aphasia
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0.5 %Epilepsy
Prevalence
Monotherapy
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65% Controlled
35%Not
0.5 %Epilepsy
Prevalence
5-10% Cumulative
Monotherapy
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65% Controlled
35%Not
0.5 %Epilepsy
Prevalence
5-10% Cumulative
50% OffMedication in
2 years
Monotherapy
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65% Controlled
35%Not
0.5 %Epilepsy
Prevalence
5-10% Cumulative
50% OffMedication in
2 years
Monotherapy
Polytherapy
70% Not
30% Controlled
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65% Controlled
35%Not
0.5 %Epilepsy
Prevalence
5-10% Cumulative
50% OffMedication in
2 years
Monotherapy
Polytherapy
70% Not
30% Controlled
New Antiepileptic DrugsSurgery Ketogenic DietSteroidsBromidesVagal Nerve StimulatorOther ??
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Objectives __________________________________________
Be aware of the effects of age and economic development on the incidence and prevalence of epilepsy.
Know how etiology varies with age of onset of seizures and epilepsy.
Know the conditions that are often associated with epilepsy.
Recognize that a majority of cases of epilepsy remit spontaneously.
Recognize risk factors for intractability.