Unchanged total number of neurons in motor cortex and neocortex in amyotrophic lateral sclerosis: a stereological study

Modern stereological methods provide precise and reliable estimates of the number of neurons in specific regions of the brain. The total number of neu rons in the neocortex and motor cortex from eight patients suffering from a myotrophic lateral sclerosis (ALS) and nine controls was estimated. No atte mpt was made to estimate subpopulations of neurons such as the number of gi ant pyramidal cells of Betz. No difference was found in the average number of neurons in neocortex in ALS and controls, 21.7 and 22.3 x 10(9), respect ively, and 1.33 and 1.29 x 10(9) in motor cortex, respectively. In the ligh t of our stereological measurements, results obtained from in-vivo proton m agnetic resonance spectroscopy (H-1-MRS), suggesting neuronal loss in ALS, may instead be due to neuronal metabolic dysfunction and/or alteration in t he size or the volume fraction of the neurons. (C) 2000 Elsevier Science B. V. All rights reserved.