epidemiology

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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4

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

19

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

22

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

28

65% Controlled

35%Not

0.5 %Epilepsy

Prevalence

5-10% Cumulative

50% OffMedication in

2 years

Monotherapy

29

65% Controlled

35%Not

0.5 %Epilepsy

Prevalence

5-10% Cumulative

50% OffMedication in

2 years

Monotherapy

Polytherapy

70% Not

30% Controlled

30

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.