Preferential neurodegeneration in the cervical spinal cord of progressive supranuclear palsy

Spinal cord lesions have seldom been described in cases with progressive supranuclear palsy (PSP). We thus decided to analyze spinal cord lesions by microtubule-associated protein 2 (MAP2) immunohistochemistry in six cases of PSP, five cases of Parkinson's disease (PD) and two cases of corticobasal degeneration (CBD), all of which cause parkinsonism, while six patients without any neurological disease served as controls. In the PSP cases, the MAP2 expression in the cervical spinal cords significantly decreased in the medial division of the anterior gray horn, intermediate gray and posterior gray horn, but showed no significant change in the substantia gelatinosa and lateral division of the anterior gray horn. The thoracic and lumbar spinal cords were well preserved for MAP2 immunoreactivity. In addition, the globose type neurofibrillary tangles and glial fibrillary tangles were more conspicuous in the cervical than in the thoracic and lumbar spinal cord in PSP cases. On the other hand, the PD and CBD cases showed no significant decrease of MAP2 immunoreactivity in the spinal cords. The small neurons, which are located rather selectively in the intermediate zone of the spinal cord, are considered to be mostly present in the interneurons, and are also thought to play a role in various types of focal dystonia, such as neck dystonia. We therefore consider the distinct decrease in the MAP2-positive neuronal processes in the cervical spinal cord may partly reflect the loss of interneurons and may, thereby, possibly cause nuchal dystonia.