UBIQUITINATED DYSTROPHIC NEURITES SUGGEST CORTICOSPINAL DERANGEMENT IN PATIENTS WITH AMYOTROPHIC-LATERAL-SCLEROSIS

Pathologic changes affecting the upper motoneuron (UMN) were studied i n 37 cases of amyotrophic lateral sclerosis (ALS) by histology and imm unohistochemistry and by electron and immunoelectron microscopy. The m ost striking finding was represented by ubiquitin-positive dot-like st ructures related to (1) glial lipofuscin granules, (2) small polygluco san bodies and (3) dystrophic neurites. Their distribution areas did n ot overlap. In ALS cases, ubiquitinated dystrophic neurites were twice as frequent as in controls in the arcuate region of motor cortex; mor eover, in ALS cases they were twice as frequent in the spinal cord at the end of corticospinal tracts, compared with the motor cortex. These findings may indicate the presence in ALS of a 'dying-back' of the co rticospinal motoneuron, independently of its primary or secondary invo lvement.