CHANGES OF UNMYELINATED NERVE-FIBERS IN SURAL NERVE IN AMYOTROPHIC-LATERAL-SCLEROSIS, PARKINSONS-DISEASE AND MULTIPLE SYSTEM ATROPHY

Quantitative changes in unmyelinated nerve fibers (UMNFs) of sural ner ves in patients of amyotrophic lateral sclerosis (ALS), Parkinson's di sease (PD) and multiple system atrophy (MSA) were evaluated using auto psy materials whose pathological diagnosis had been confirmed by caref ul postmortem examinations. Ordinary ALS cases demonstrated no involve ment in cutaneous UMNFs; however, the patients with long survival due to the application of ventilatory support showed bimodality in UMNF di ameter histograms, and a patient with involvement of systems other tha n motor pathways showed an abnormal value in two indices: a low percen tage of subunits containing axon(s) and a high mean number of Schwann cell profiles per axon. A significant reduction of the mean value of U MNF density (21%) was found in PD patients. Because the density of mye linated nerve fibers did not show any significant decrease as compared with age-matched controls, the change of nerve fibers in peripheral n ervous system was considered to be confined to UMNFs in PD. Elderly PD cases showed enhanced changes in the ageing process, as expressed by the two indices described above. In MSA, the mean value of UMNF densit y was significantly decreased (23%), and this decrease almost parallel ed that of myelinated nerve fiber density. Abnormal values for the two indices described above were found and two out of four cases demonstr ated bimodality in the diameter histogram of UMNFs. Unlike MSA, ALS an d PD have not been included in the disorders with cutaneous UMNF invol vement. Our results supply the first evidence of morphological changes in cutaneous UMNFs in PD cases. In ordinary ALS cases, the emergence of such morphological changes is suggested in cases with long survival .