1. Approach to Myoclonic seizures
in Childhood

2. Myoclonus
• Myoclonus is a brief, involuntary muscle
contraction (jerk) that may represent
• (1) a seizure manifestation, as in infantile
spasms;
• (2) a physiological response to startle or to
falling asleep; or
• (3) an involuntary movement either alone or
in combination with tonic-clonic seizures

3. CLINICAL AND ETIOLOGIC
CLASSIFICATION
• Marsden and colleagues
• Physiologic
• Essential
• Epileptic
• Secondary (symptomatic)

4. Physiologic myoclonus
(normal subjects)
• A. Sleep jerks (eg, hypnic jerks)
• B. Anxiety-induced
• C. Exercise-induced
• D. Hiccough (singultus)
• E. Benign infantile myoclonus with feeding

5. Essential myoclonus
(primary symptom, nonprogressive history)
• A. Hereditary (autosomal dominant)
• B. Sporadic

6. Epileptic myoclonus
• Fragments of epilepsy
• Myoclonic epilepsy syndromes
• Familial cortical myoclonic tremor with
epilepsy

7. Fragments of epilepsy
• Isolated epileptic myoclonic jerks
• Epilepsia partialis continua (focal status
epilepticus)
• Idiopathic stimulus-sensitive myoclonus
• Photosensitive myoclonus
• Absences with a minor myoclonic component
• Epilepsy with myoclonic absences

8. Myoclonic epilepsy syndromes
• Infantile spasms (West syndrome)
• Severe myoclonic epilepsy of infancy (Dravet
syndrome)
• Benign myoclonic epilepsy of infancy
• Lennox-Gastaut syndrome
• Myoclonic astatic epilepsy (Doose syndrome)
• Cryptogenic myoclonus epilepsy (Aicardi)
• Juvenile myoclonic epilepsy (Janz syndrome)
• Familial cortical myoclonic tremor with epilepsy

9. Familial cortical myoclonic tremor
with epilepsy
• Autosomal dominant inheritance
• Adult onset
• Distal action tremor and myoclonus
• Infrequent, secondarily generalized tonic-
clonic seizures
• Relatively benign course, typically with normal
cognition
• Responsiveness to anticonvulsants.

10. Symptomatic (secondary) myoclonus
• Post–central nervous system injury
• Basal ganglia degenerations
• Drug-induced
• Storage disorders
• Viral encephalitis

11. Early infantile epileptic
encephalopathies
• Early myoclonic infantile encephalopathy
• Early epileptic infantile encephalopathy
(Ohtahara syndrome)

12. Epilepsy syndromes with myoclonic
seizures
• West syndrome
• Lennox-Gastaut syndrome
• Myoclonic astatic epilepsy (Doose syndrome)
• Severe myoclonic epilepsy of infancy (Dravet
syndrome)

13. West syndrome
• Starts between the ages of 2 and 12 months
• Triad of infantile spasms that usually occur in
clusters (particularly in drowsiness or upon
arousal), developmental regression, and a
typical EEG picture – hypsarrhythmia.
• Either cryptogenic or symptomatic
• ARX gene (ambiguous genitalia)
• Medical emergency (critical period of 3 weeks)

14. Lennox-Gastaut syndrome
• Between the age of 2 and 10 years
• Triad of developmental delay, multiple seizure
types and 1-2 Hz spike–and-slow
waves, polyspike bursts in sleep, and a slow
background in wakefulness.

15. Myoclonic astatic epilepsy (Doose
syndrome)
• Onset of seizures is between the ages of 2 and
5 years
• Similar to but milder than Lennox-Gastaut
syndrome
• Does not have tonic seizures or polyspike
bursts in sleep
• Prognosis is more favorable

16. Dravet syndrome
• Most severe of the phenotypic spectrum of
febrile seizures plus
• Onset is in the 1st year of life, characterized by
febrile and afebrile unilateral clonic seizures
recurring every 1 or 2 months.

17. Progressive myoclonic epilepsies
• Progressive dementia and worsening
myoclonic and other seizures.
• Type I or Unvericht Lundborg disease is more
slowly progressive than the other types and
usually starts in adolescence.
• Type II or Lafora body disease can have an
early childhood onset but usually starts in
adolescence, is more quickly progressive, and
is usually fatal.

18. Treatment - General
• Patients with benign forms of myoclonic
epilepsy often respond well to valproic acid or
clonazepam.
• The duration of treatment is usually
approximately 5 years.
• Second-line medications include
ethosuximide, zonisamide, and topiramate.

19. Treatment - Specific
• West syndrome is best treated with ACTH.
• Vigabatrin - approved by the FDA for use in
children with infantile spasms.
• Treatment of seizures in Lennox-Gastaut
syndrome varies according to the
preponderant seizure type.

20. Treatment - Specific
• Dravet syndrome is usually treated with
valproate and benzodiazepines such as
clonazepam.
• Lamotrigine has been reported to exacerbate
seizures in Dravet syndrome and other
myoclonic epilepsies
• Stiripentol and ketogenic diet may have a
niche role in treating Dravet syndrome.