Histological and electrophysiological changes of the lower motor neurone with aging

Maximal motor conduction velocity of ulnar nerve was measured in 7 patients 80-93 years old, who suffered from cerebro-vascular stroke. In 2 cases motor conduction velocity was significantly decreased. Specimens for histopathological study were taken from the spinal cord at the C8 and Th1 segments and from the ulnar nerve at the elbow level on the side opposite to the hemiparesis. In 100 sections of each senile case and in 3 control cases of younger individuals the motoneurons of the retro-postero-lateral nucleus with visible nucleoli were counted. In the ulnar nerve qualitative and quantitative examinations were performed. The study showed a significant loss of motoneurons in the nucleus and a loss of myelinated fibers especially the thickest ones in the ulnar nerve in elderly cases. In teased preparations axonal degeneration and segmental demyelination of some fibers were seen. Morphological changes in some cases, resulted in a slowed down motor conduction velocity.