[Cortical spreading depolarization: an underestimated phenomenon after human brain injury?]

Background and purpose: Cortical spreading depolarization waves (CSD) are massive temporary neuronal depolarizations that slowly propagate through cerebral cortex from brain injured tissue. CSD waves cause temporary brain electrical silence, local tissue hemodynamic responses and metabolic increases required for cellular repolarization. Due to this metabolic imbalance in compromised tissue, CSD could participate in the extension of secondary insults after brain injury. From the analysis of the human literature, we aimed at determine the CSD incidences in brain injured patients.

Methods: Medline(®) research: "cortical spreading depolarization" and "brain injury", and "human" limits from 1980 to 2011.

Results: Ten original studies were found. CSD occurred in more than 50% of patients monitored for CSD after different brain injury (traumatic, subarachnoid haemorrhage, malignant stroke, spontaneous intracranial haemorrhage). When detected, CSD were associated with a significantly worse neurological outcome. To be identified, CSD required specific devices that directly record cortical electrical depression by a multipolar electrode positioned at the cortex surface or by indirect analysis of hemodynamic and metabolic consequences of the CSD.

Conclusions: When monitoring tools are available, CSD occur in more than 50% of brain injured patients. Today results come from clinical research. Future studies are necessary to determine the impact of CSD detection on care and potential therapeutics aimed at counteracting these adverse events.