we st syndrome eeg
DESCRIPTION
eeg in west syndromeTRANSCRIPT
EEG IN WEST SYNDROME:Dr.Roopchand.PS
Senior Resident Academic
Department of Neurology
TDMC, Alappuzha
Overview• Severe epilepsy syndrome composed of the triad of
infantile spasms, an interictal EEG pattern termed hypsarrhythmia, and mental retardation.
• Dr W J West, gave the first detailed description of infantile spasms.
• Published in The Lancet in 1841.• Generalized Flexion Epilepsy, Infantile Epileptic
Encephalopathy, Infantile Myoclonic Encephalopathy, jackknife convulsions, Massive Myoclonia , Salaam spasms.
• Reflect abnormal interactions between the cortex and brainstem structures.
• Insult to the immature CNS.• Brain-adrenal axis.
• stressors in the immature brain produces an abnormal, excessive secretion of corticotropin-releasing hormone (CRH), causing spasms.
• Based on etiology classified in to• Symptomatic• Cryptogenic• idiopathic.
• Two specific genetic defects have a phenotypic presentation similar to that of the early onset of infantile spasms.• gene ARX mutation• cyclin-dependent kinase-like protein 5 (CDKL5) mutation
• 2% of childhood epilepsies, 25% of epilepsy with onset in the first year of life.
• Males are affected slightly more then females.• Onset is before 12 mo of age.
• Peak onset between 4 to 6 mo.
• Only 14% of infants with symptomatic West syndrome have normal or borderline-normal cognitive development.
• 50-70% of patients develop other seizure types.• 18-50% of patients will develop Lennox-Gastaut
syndrome or some other form of symptomatic generalized epilepsy.
• 70% dies before 20 yrs of age.
Hypsarrhythmia:• Hypsarrhythmia is the characteristic interictal EEG
pattern.
• Chaotic, high- to extremely high–voltage, polymorphic delta and theta rhythms with superimposed multifocal spikes and wave discharges.
• Gibbs and Gibbs described hypsarrhythmia in 1952.• Unilateral hypsarrhythmia and asymmetrical ictal EEG
changes during spasms are correlated with focal or asymmetrical cerebral lesions on imaging studies.
• Hypsarrhythmia either disappears or improves during a cluster of spasms and/or REM sleep.
• Hypsarrhythmia rarely persists beyond the age of 24 months.
Defining characteristics(Gibs and Gibs):
• Essentially continuous• Present in both awake and sleep• Consist of random high voltage slow waves and spikes.• Spikes vary in location and duration – focal or multifocal• Occasionally generalized discharges but never in a
rhythmic or highly organized pattern.
• Five variants of the "classical" hypsarrhythmic pattern have been identified.
• Hypsarrhythmia with increased interhemispheric synchronization (35%).
• Asymmetric hypsarrhythmia (12%).• Hypsarrhythmia with a consistent focus of abnormal
discharge (26%).• Hypsarrhythmia with episodes of voltage attenuation
(11%).• Hypsarrhythmia without spike or sharp activity (7%).
Hypsarrhythmia with increased interhemispheric synchronization:
Asymmetric hypsarrhythmia:
Focal Hypsarrhythmia:
Hypsarrhythmia with episodes of voltage attenuation:
Factors influencing Hypsarrhythmia pattern:
• It is a highly dynamic pattern:• Sleep:
• NREM – increase in amplitude of waves, grouping of spikes, sharps and slow waves, sometimes attenuation.
• REM: complete to near complete disappearance of hypsarrhythmia pattern.
• Normalization can also be seen upon waking up.
• Ictal events:• After a seizure episode there can be transient periods of decreased
abnormal activity and normalization of background.
• Evolution with time:• Hypsarrhythmia pattern tends to decrease with time and
disappears by 5 to 7 years.
Precursors of hypsarrhythmia:
• Focal or multifocal spikes• B/L parieto temporal dominant spikes• Burst suppression pattern.
Significance of interictal pattern: • Diagnostic value: very strong indicator of infantile spasms.• Correlation with etiology:
• Asymmetric and focal findings correlate with a symptomatic etiology.
• Hemi hypsarrhythmia pattern seen in cerebral dysgenesis• HIE- absence of sleep pattern.
• Correlation with outcome:
ICTAL PATTERNS:
• Kellaway et al.• Described 11 different patterns.• High amplitude fast activity is the most commonest.• Asymmetry indicates possible symptomatic etiology.
• Infantile Spasms: Diagnosis, Management and Prognosis• James D. Frost Jr., Richard A. Hrachovy - 2003
Thank You