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LENNOX GASTAUT SYNDROME

Background

The EEG background is abnormal in all cases from onset of seizures, with generalized or focal slowing.

CAUTION If there is prominent bi-parietal rhythmic theta right arrow consider epilepsy with myoclonic-atonic seizures.

Interictal

There may be focal or multifocal spike-and-wave or sharp-slow waves, with an anterior predominance. Slow (<2.5 Hz) spike-and-wave and paroxysmal fast activity (10 Hz or greater) in slow sleep are mandatory requirements. Periods of suppression of the EEG may occur.

CAUTION Fast spike-and-wave (3 Hz or higher) right arrow consider other epilepsy syndromes.

CAUTION Continuous spike-and-wave during slow sleep right arrow consider epileptic encephalopathy with continuous spike-and-wave during sleep or Landau Kleffner syndrome.

Activation

Hyperventilation (if adequate co-operation) may facilitate spike-and-wave and atypical absences. Slow (<2.5Hz) spike-and-wave and paroxysmal fast activity are prominent in slow sleep. Focal and multifocal abnormalities seen in the awake state become bisynchronous in sleep.

CAUTION If activation with intermittent photic stimulation right arrow consider epilepsy with myoclonic-atonic seizures.

Ictal

For ictal EEG patterns, refer to individual seizure types.

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