Changes in cerebral circulation and neuronal metabolism during chronic cerebral vasospasm after sub-arachnoid hemorrhage

Abstract

Development of chronic cerebral vasospasm (VS) after sub-arachnoid hemorrhage (SAH) must be one of the most critical factors influencing morbidity and mortality in patients with ruptured cerebral aneurysm. We studied how neuronal cells are affected by alteration of cerebral circulation and metabolism during VS in a primate model. The SAH was induced in the right basal cisterns in monkeys. Angiography presented VS maximally 7 days after SAH. In the area of VS, cerebral blood flow (CBF) showed a significant reduction accompanied by an impairment of CBF autoregulation from the acute to maximum stage of VS. In this region, cerebral energy metabolism was critically depleted and microcirculation was impaired in a state of impaired CBF autoregulation. The observation by proton magnetic resonance spectroscopy (MRS) in an experimental model demonstrated a small but significant loss of neuronal cells during development of VS. The MRS study in SAH patients also demonstrated the injury in a subpopulation of neurons during development of VS or after SAH. The results indicated that the brain areas of VS are so seriously affected to exist near ischemic threshold, in states of impaired autoregulation. These critical states possibly influence the neuronal cells to survive during development of VS after SAH.