INVOLVEMENT OF ONUF NUCLEUS IN AMYOTROPHIC-LATERAL-SCLEROSIS

The Onufrowicz (Onuf's) nuclei from eight amyotrophic lateral sclerosi s (ALS) cases and nine neurological control cases were studied histolo gically and morphometrically. To clarify the factors relating to the i nvolvement of the Onuf's nucleus in ALS, we correlated the relationshi ps among the age at death, clinical duration, morphometric findings fo r Onuf's neurons, and neuronal numbers in the posteroposterolateral (P PL) nuclei in the ALS cases with those in neurological controls. Intra cytoplasmic inclusions such as Bunina bodies, ubiquitin-reactive inclu sions, and conglomerate inclusion were found in the Onuf's neurons in ALS, but not in the controls. The total number of Onuf's neurons in th e ALS cases was not decreased, but that of normal-appearing neurons wa s decreased while that of atrophic neurons was increased. Significantl y decreased perikaryal, nuclear and nucleolar areas and decreased peri karyal (P)/nuclear and P/nucleolar area ratios of Onuf's neurons were found in ALS, not only in the atrophic neurons but also in the normal- appearing neurons, compared with the controls. The shrinkage in Onuf's neurons of ALS was different from that seen in the ageing process or in the axonal reactions of controls with atonic bladder. In ALS, the m orphometric findings for the Onuf's neurons showed no correlation with age al death, clinical duration, or number of PPL neurons. Our result s indicate that in ALS Onuf's nucleus is principally vulnerable to the ALS process, although the degree of degeneration differs from that se en in other motor neurons. The involvement of Onuf's nucleus might be slowed due to factors specific to this nucleus, including the biochemi cal and autonomic properties of the nucleus; nevertheless, it is histo logically classified as part of the somatic cell column. (C) 1997 Else vier Science B.V.