High Variability in Neuronal Loss.

Background and Purpose- In the setting of acute ischemic stroke because of large-vessel occlusion (LVO) there is progressive loss of brain tissue which occurs in a time-dependent fashion previously quantified to be ≈1.9 million neurons per minute. However, this number represents an average and accumulating evidence suggests large individual variation. In this study, we aim to quantify the distribution and range in the rate of loss brain tissue across the entire spectrum of clinical phenotypes of anterior circulation LVO strokes encountered in clinical practice. Methods- Retrospective review of a prospectively acquired database of consecutive patients with anterior circulation stroke because of proximal LVO and appropriate ischemic core imaging was performed. Ischemic core volume was measured using automated software processing and time from last known well to imaging was recorded. Applying previously published methodology for brain loss quantification, we computed rate of brain tissue elements loss in proximal LVO stroke patients. Results- We studied 415 patients with internal carotid artery or middle cerebral artery (M1 segment) occlusion. Mean ischemic core volume was 50.4 mL and mean time to imaging from time from last known well (TLKW) was 8.7 hours, which is similar to previously published data, translates into a mean loss per minute of 2.03 million neurons, 14.8 billion synapses, and 12.8 km of myelinated fibers. However, the distribution of neuron loss was highly variable, ranging from <35 000 to >27 million cells per minute. Conclusions- Widely spread rates of infarct growth are observed in acute ischemic stroke because of proximal LVO with rate of neuron loss per minute ranging from <35 000 per minute in slow progressors to >27 million per minute in fast progressors, with a mean and median of 2 million and 0.9 million, respectively.