Aging and the human vestibular nuclei: morphometric analysis

The data concerning the effects of age on the brainstem are scarce and few works are devoted to the human vestibular nuclear complex. The study of the affects of aging in the vestibular nuclei could have clinical interest due to the high prevalence of balance control and gait problems in the elderly . We have used in this work eight human brainstems of different ages sectio ned and stained by the formaldehyde-thionin technique. The neuron's profile s were drawn with a camera lucida and Abercrombie's method was used to esti mate the total number of neurons. The test of Kolmogorov-Smirnov with the c orrection of Lilliefors was used to evaluate the fit of our data to a norma l distribution and a regression analysis was done to determine if the varia tion of our data with age was statistically significant. Aging does not aff ect the volume or length of the vestibular nuclear complex. Our results cle arly show that neuronal loss occurs with aging in the descending (DVN), med ial (MVN), and lateral (LVN) vestibular nuclei, but not in the superior (SV N). There are changes in the proportions of neurons of different sizes but they are not statistically significant. The neuronal loss could be related with the problems that elderly people have to compensate unilateral vestibu lar lesions and the alterations of the vestibulospinal reflexes. The preser vation of SVN neurons can explain why vestibule-ocular reflexes are compens ated after unilateral vestibular injuries. (C) 2000 Elsevier Science Irelan d Ltd. All rights reserved.