Recording, analysis, and interpretation of spreading depolarizations in neurointensive care: Review and recommendations of the COSBID research group
Authors: Dreier Jens P , Fabricius Martin , Ayata Cenk , Sakowitz Oliver W , William Shuttleworth C , Dohmen Christian , Graf Rudolf , Vajkoczy Peter , Helbok Raimund , Suzuki Michiyasu , Schiefecker Alois J , Major Sebastian , Winkler Maren KL , Kang Eun-Jeung , Milakara Denny , Oliveira-Ferreira Ana I , Reiffurth Clemens , Revankar Gajanan S , Sugimoto Kazutaka , Dengler Nora F , Hecht Nils , Foreman Brandon , Feyen Bart , Kondziella Daniel , Friberg Christian K , Piilgaard Henning , Rosenthal Eric S , Westover M Brandon , Maslarova Anna , Santos Edgar , Hertle Daniel , Sánchez-Porras Renán , Jewell Sharon L , Balança Baptiste , Platz Johannes , Hinzman Jason M , Lückl Janos , Schoknecht Karl , Schöll Michael , Drenckhahn Christoph , Feuerstein Delphine , Eriksen Nina , Horst Viktor , Bretz Julia S , Jahnke Paul , Scheel Michael , Bohner Georg , Rostrup Egill , Pakkenberg Bente , Heinemann Uwe , Claassen Jan , Carlson Andrew P , Kowoll Christina M , Lublinsky Svetlana , Chassidim Yoash , Shelef Ilan , Friedman Alon , Brinker Gerrit , Reiner Michael , Kirov Sergei A , Andrew R David , Farkas Eszter , Güresir Erdem , Vatter Hartmut , Chung Lee S , Brennan KC , Lieutaud Thomas , Marinesco Stephane , Maas Andrew IR , Sahuquillo Juan , Dahlem Markus A , Richter Frank , Herreras Oscar , Boutelle Martyn G , Okonkwo David O , Bullock M Ross , Witte Otto W , Martus Peter , van den Maagdenberg Arn MJM , Ferrari Michel D , Dijkhuizen Rick M , Shutter Lori A , Andaluz Norberto , Schulte André P , MacVicar Brian , Watanabe Tomas , Woitzik Johannes , Lauritzen Martin , Strong Anthony J , Hartings Jed A 
Published: June 2016

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches.