Spinal cord and parkinsonism: neuromorphological evidences in humans and experimental studies

The involvement of the spinal cord in parkinsonism is becoming more and more evident based on human autopsies and on experimental models, obtained using specific neurotoxins or genetic manipulations. Besides Parkinson disease, other degenerative disorders characterized by parkinsonism, involve the spinal cord, and multiple neurotransmitters, apart dopamine, are altered in parkinsonism, also in their spinal projections. In the present review we discuss spinal cord pathology of different genetic or toxic experimental models of parkinsonism, as well as the neuropathological reports from autoptic cases of sporadic Parkinson disease and of other neurodegenerative conditions, overlapping with parkinsonism. Furthermore, anatomical distribution of alpha-synuclein in the spinal cord and coeruleo-spinal projections are reviewed, at the light of their possible involvement in spinal neurons degeneration. All these evidences call for an anatomical stemmed novel approach to understand specific features of parkinsonism, which might be due to such an involvement of the spinal cord. Moreover they suggest a common neurodegenerative process, underlying distinct neurodegenerative disorders, to which spinal neurons could be the more sensible.