Neurofibrillary axonal swellings and amyotrophic lateral sclerosis.

A series of 22 cases of amyotrophic lateral sclerosis (ALS) and 22 controls have been assessed for the presence of neurofilamentous accumulations in axons and perikarya. Large axonal swellings were seen in the spinal cord of 12 controls and of 13 ALS cases. When they were present in ALS cases they tended to be much more numerous than in controls, and when they were not present in ALS cases there tended to be severe neuronal loss in the cord. Axonal swelling on lower motor neurons appears to be a significant feature of the pathology of ALS. Its implications in terms of etiology are unknown.