The size distribution of neurons in the motor cortex in amyotrophic lateral sclerosis.

The motor cortex of eight patients with amyotrophic lateral sclerosis (ALS) and nine control subjects was used in the study. Recent stereological tools, the disector and the rotator method, were applied to the motor cortex of patients with ALS and control subjects to obtain estimates of mean perikaryon volume, mean neuronal nuclear volume, total perikaryon volume and total neuronal nuclear volume. No significant differences were found in any of the estimates. In vivo proton magnetic resonance spectroscopy studies show a decrease in the concentration of neuronal markers. We expected to find changes in perikaryon and/or nuclei neuronal volume because the total neuron number is unchanged in ALS compared with control subjects. However, this was not the case; our results suggest that metabolic changes take place in the motor cortex of ALS patients without these concomitant anatomical changes.