New pathological findings in amyotrophic lateral sclerosis.

There have been recent developments in the pathology of sporadic ALS. A new filamentous neuronal inclusion body in ALS detected by immunohistochemical localisation of the protein ubiquitin has been characterised at the light microscopic and ultrastructural level and appears specific for the disease. The molecular composition of underlying filaments remains unresolved but the quest for this is a major aim in ALS research. Despite being a progressive degenerative process which primarily affects motor systems, ALS is now recognised to involve several non-motor systems and in long survivors affects many subcortical structures. There is also accumulating evidence that the neurodegenerative process underlying ALS may present as a non-motor clinical syndrome, particularly as a frontal lobe dementia with characteristic inclusions present in the non-motor cortex. Considering ALS as a multisystem disease rather than simply a disease of motor neurones has major implications for research into pathogenesis.