This document discusses several epileptic encephalopathies: - Early myoclonic encephalopathy presents in neonates and is characterized by fragmentary myoclonus, erratic seizures, and a suppression-burst EEG pattern. Prognosis is poor with over 50% mortality. - Ohtahara syndrome presents from 10 days to 3 months of age with tonic spasms and a suppression-burst EEG pattern in both waking and sleep states. It can progress to West syndrome and Lennox-Gastaut syndrome. - Lennox-Gastaut syndrome typically starts between ages 1-7 and is characterized by multiple seizure types, cognitive issues, and EEG showing slow spike-wave dis

1. DR SRIRAMA ANJANEYULU
MD DM
NEUROLOGIST

2.  Severe brain disorders in which the epileptic electrical
discharges may contribute to progressive psychomotor
dysfunction.
 Early age of presentation.
 EEG paroxysmal activity.
 Multi-form,intractable and often aggressive seizures.
 Severe cognitive, behavioural and neurological deficits.
 Poor prognosis with occ. early death.

3.  Neonates.
 Early myoclonic encephalopathy.
 Ohtahara syndrome.
 Infancy.
 West syndrome.
 Dravet syndrome.
 Childhood.
 Myoclonic astatic epilepsy.
 Epileptic encephalopathy with CSWS including Landau-
Kleffner syndrome.
 Lennox – Gastaut syndrome.
 Rasmussen syndrome.

4. Evolution of epileptic encepaphalopathies

5. Early Myoclonic Encephalopathy
 Onset < age 3 m, initially fragmentary myoclonus and then erratic focal
seizures, massive myoclonias or tonic spasms.
 EEG - suppression–burst activity, which evolves into
hypsarrhythmia,accentuated during sleep,persists for prolonged
periods.
 Inborn errors of metabolism mc causes.
 >50% die within weeks or months.

6. The inter-ictal EEG of early myoclonic encephalopathy is a
repetitive suppression–burst pattern without physiological
rhythms

7. Ohtahara Syndrome (early infantile epileptic encephalopathy
with suppression–burst).
 10 days to 3 months of age (occ. Intrauterine).
 Tonic spasms - forward tonic flexion lasting 1–10 s that is
singular or in long clusters 10–300 times every 24 h.
 1/3rd - erratic focal motor clonic seizures.
 Alternating hemiconvulsions or GTCS are exceptional.
 Myoclonic seizures are rare.
 ILAE Definition
 Very early onset, within the first few months of life, frequent tonic
spasms and a suppression–burst EEG pattern in both the waking
and sleeping states.

8.  The EEG - Bursts last for 2–6 s with intermixed suppression period
which lasts for 3–5 s.
 Tonic spasms -ictal EEG.
 Diffuse desynchronisation with disappearance of suppression–burst
activity when tonic spasms cluster in intervals of 5–10 s.
 A pattern in which the suppression–burst pattern becomes more
frequent, more diffuse and of higher amplitude compared to the
inter-ictal pattern.
 Progression of Clinical and Electroencephalogram Features to
West Syndrome and LGS.
 Gradual disappearance of the BSP and the emergence of
hypsarrhythmia within 3–6 mths from onset which progress later to
the slow spike-wave EEG patterns of LGS.

9. Ohtahara syndrome: suppression – burst pattern

10. West syndrome (Epileptic spasms).
 Triad of infantile spasms, arrest of psychomotor development, and
hypsarrhythmia.
 Onset peaks between the ages of 4 and 7 months.
 Clusters of sudden, brief (0.2–2 s), bilateral tonic contractions of the
axial and limb muscles.
 1–30% may have lateralising features.
 Precipitating factors- twilight state,sudden loud noises or tactile
stimulation,feeding.
 Gibbs and Gibbs –hypsarrhythmic interictal EEG.
 Lissencephaly and Aicardi syndrome -frequent suppression–burst
activity.
 West syndrome of TS- spike foci with SBS in sleep are frequent.

12. EEG of a 6-month-old infant with developmental delay and infantile spasms,
showing typical hypsarrhythmic pattern.

13. Ictal EEG
 Variable lasting for 0.5 s to 2 min.
 Brief attacks (1–5s) consisting of:
 a high-voltage, generalised slow wave.
 episodic, low-amplitude fast activity.
 marked diffuse attenuation of EEG electrical activity
(electrodecremental ictal EEG pattern).
 Prognosis
 Mortality - 5%.
 60% - develop other seizure types
 50%-permanent motor disabilities
 2/3rd -severe cognitive and psychological impairment.
 5–12% - normal mental and motor development.

15. Infantile spasm noted in second 7 with an electrodecremental response
obtained in a 3-yr-old child with TS.

16. Dravet Syndrome (Severe Myoclonic Epilepsy in Infancy)
 Onset is always <1yr of life, with a peak age of 5 m.
 Tetrad of seizures
 Early onset infantile febrile clonic convulsions
 Myoclonic jerks
 Atypical absences
 Complex focal seizures.
 Precipitating Factors
 Febrile illnesses , warm environment (hot baths), Photic and
pattern stimulation, movements and eye-closure.

17.  Inter-Ictal EEG
 Initial -20% show normal BG with photoparoxysmal
discharges of spikes/ polyspikes-slow waves.
 Within 1 year, EEG - abnormal slow BG with frequent
asymmetrical paroxysms of polyspikes or spikes-slow
waves.
 Ictal EEG
 Varies according to seizure type.

18. Lennox–Gastaut Syndrome
 Starts between 1 and 7 yrs with a peak at 3–5 years.
 10–30% of cases develop from West syndrome or other epileptic
encephalopathies.
 Triad of
 Polymorphic intractable seizure that are mainly tonic (80%),
atonic (50%)and atypical absence seizures (70%), Myoclonic
Jerks(11–28%).
 Cognitive and behavioural abnormalities.
 EEG with paroxysms of fast activity and slow (less than 2.5 Hz)
generalised spike-wave discharges (GSWD).

19. Tonic seizure started clinically
with a scream (vertical
arrow) and episodic
nystagmus (oblique arrows
shows EM artefacts).
The ictal EEG consisted of an
abrupt onset of flattening,
which lasted for 25 s,
followed by high-amplitude
generalised sharp and slow
waves at approximately 1 Hz.
The EEG returned to its pre-
ictal state after
approximately 1 min from the
onset of the seizure.

20. EEG fast paroxysms are associated with inconspicuous manifestations of
tonic seizures (slight tonic eyelid opening).

23. Ictal discharge contains
features of tonic (episodic
fast activity) and absence
(slow spikes and waves)
seizure.

24. Fast paroxysms contain rhythms > 10 Hz. MISD mainly occur in the
transition from West to LGS.
Very rapid (20 ± 5 Hz) and initially of low amplitude,
progressively increasing to 50–100 mV.

25. EEG of a 16-yr-old child with MR and tonic seizures, showing slow spike wave
activity superimposed on a slow BG.

26. EEG of an 11-yr-old pt with LGS showing GPFA.

27. Tonic seizure in a patient with LGS.

28. Landau–Kleffner Syndrome Acquired Epileptic Aphasia)
 Partly reversible, epileptic encephalopathy of childhood
manifesting with acquired verbal auditory agnosia and
fluctuating course of the linguistic disturbances that occur
together with other cognitive and neuropsychological
behavioural abnormalities.
 Age at onset : 2–8 yrs with a peak at 5–7 yrs.
 Epileptic seizures and behavioural and psychomotor
disturbances occur in 2/3rd of patients.

29. Inter-ictally, clusters of
sharp-slow wave focal
discharges maximum
around the left Rolandic
regions (left). They became
continuous during natural
sleep (right).
Ictal discharge starts from
the left central regions and
rapidly spreads to the
neighbouring regions. The
first clinical signs consisted
of right facial spasms
(arrow; also note muscle
artefacts on the right)
progressing to hemi-
convulsions.

31.  Prognosis
 Seizures and EEG abnormalities usually remit by 15yrs of
age.
 50% of patients -relatively normal life with 10–20%
achieving complete normalisation.
 50% left with permanent sequelae that may be very
severe.

32. ESES in a 9-year-old boy with Landau-Kleffner syndrome.

33. Epilepsy with Continuous Spike and Waves during Slow-Wave Sleep
(Epileptic Encephalopathy with Electrical Status Epilepticus during
Slow-Wave Sleep)
 Partly reversible, age-related childhood epileptic
encephalopathy characterised by the triad of:
 EEG CSWS
 Seizures(except tonic seizures).
 Neuropsychological and motor impairment.
 Onset of seizures - 2 m to12 yrs, with a peak at 4–5
yrs.

35. 3 stages of evolution.
 I stage is before the discovery of CSWS
 The EEG shows multi-focal spikes and bisynchronous generalised
sharp or spike-wave discharges.
 II stage is when CSWS is found
 Increase in seizures and the appearance or deterioration of
neuropsychological symptoms that prompt a sleep EEG.
 Continuous bilateral and diffuse slow spikes-waves of 1.5–2 Hz
during NREM sleep is the defining EEG pattern of ECSWS.
 III stage is after clinical and EEG remission starts.

36. Encephalopathy with CSWS