History of the Letzte Wiese/Last Meadow Concept of Brain Ischemia

In the history of stroke research the term letzte Wiese (English last meadow or last field) was introduced in the early fifties of the past century to describe the risk of low blood perfusion in the periphery of a vascular territory. The term appears 1952 in the discussion of a colloquium held by the German Society of Physiological Chemistry in the small city Mosbach, located close to the scenic river Neckar in the north of the federal state Baden-Wurttemberg.1 The symposium entitled Chemie und Stoffwechsel des Nervengewebes (chemistry and metabolism of nervous tissue) comprised 5 presentations on various aspects of brain function and metabolism. One of these was given by Erich Opitz, Chair of the Physiological Institute of the University Kiel. In his presentation Energieumsatz des Gehirns in situ unter aeroben und anaeroben Bedingungen (energy metabolism of the brain under aerobic and anaerobic conditions), he addressed the magnitude of metabolic activity required to maintain the structural integrity of the brain (Strukturumsatz). In the discussion after his presentation, Max Schneider, Chair of the Physiological Institute of the University of Cologne, remarked that a differentiation between structural and functional activity of the brain can be obtained by gradually reducing the blood perfusion of an isolated head preparation and recording the suppression and recovery of the electroencephalogram. The lowest flow rate down to which spontaneous electroencephalogram activity persists is the amount required to maintain functional activity, and the lowest flow rate which is tolerated for some time without causing irreversible suppression of the electroencephalogram corresponds to the amount required to preserve structural integrity. This approach anticipated the latter differentiation between core and penumbra of evolving brain infarction introduced by Astrup et al2 after occlusion of the middle cerebral artery. However, as pointed out by Schneider,3 global measurements of blood flow …