E-Pearl of the Week: Slow-flat-slow

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March 29, 2013

Paroxysmal loss of consciousness due to syncope is associated with the EEG pattern of 'slow-flat-slow,' initially described by Henri Gastaut in 1974.  With the onset of cerebral hypoperfusion there is progressive slowing of the background, with disappearance of the alpha rhythm and appearance of theta and delta activity. This slow phase can last for up to 10 seconds and then abruptly disappears, leaving a 'flat' EEG. With restoration of cerebral blood flow, the same EEG phenomena occur in reverse order, thereby giving the pattern its name, 'slow flat slow.'


  1. Ziller MG, Natola MA.  EEG Findings during Tilt-Table Induced Asystole: A Case Report.  Am J Electroneurodiagnostic Technol. 2011; 51:26-30.
  2. Wieling WThijs RDvan Dijk N, et al. Symptoms and signs of syncope: a review of the link between physiology and clinical clues. Brain. 2009;132: 2630-2642.

Submitted by Charles F. Guardia III MD

Disclosure: Disclosures: Dr. Guardia reports no disclosures.

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