Proportional neuronal loss between the primary motor and sensory cortex in amyotrophic lateral sclerosis.

The number of neurons in the primary motor cortex (MI) and the primary somatosensory cortex (SI) were estimated in the same locations of brains from sporadic amyotrophic lateral sclerosis (ALS) cases and controls. The number of MI and SI neurons and Betz cells were significantly decreased in the ALS cases as compared to the controls. The number of neurons in MI and SI was independent of age at death or duration of disease. Moreover, the number of neurons in MI and SI was significantly correlated, suggesting that the neurons in both sites might be interdependent and might decrease proportionally.