Title: Introduction by Topic Editors, Gregory A. Helm, M.D., Ph.D., and Neal F. Kassell, M.D.
Abstract: During the last two decades, major advances have been made in the diagnosis and treatment of cerebral vasospasm occurring after subarachnoid hemorrhage.This field of research continues to draw the attention of numerous neurosurgical researchers.The cause of cerebral vasospasm is probably multifactorial and continues to be highly controversial.This issue contains several experimental studies supporting some of the popular theories concerning the mechanisms involved in vasospasm, including the oxyhemoglobin-mediated, calcium-dependent activation of calpain and the release of the potent endothelium-derived vasoconstricting agent endothelin-1.Two novel hypotheses are also presented; the authors discuss the possible roles played by adenosine triphosphate release during erythrocyte hemolysis and compliment membrane attack complexes in the pathogenesis in cerebral vasospasm.We anticipate that further investigation will make the field even more complex, although some of the mechanistic themes are becoming clear and several treatment paradigms are beginning to improve clinical outcome.This issue of Neurosurgical Focus should stimulate even more research activity in this fascinating field, which we hope will reveal the unified mechanisms of cerebral vasospasm and lead to its successful prevention and reversal.