Ballooned neurons in corticobasal degeneration and progressive supranuclear palsy

Abstract

We examined the distribution and immunohistochemical characteristics of ballooned neurons (BN) in the cortex of patients with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). In CBD, the BN were distributed mainly in the medial and superior areas of the frontal cortex, such as the cinglate cortex, superior frontal cortex, and precentral cortex. In six of the nine patients with PSP studied, BN were seen in the cerebral cortex. In two of these six patients, BN were abundant and cortical degeneration was present in the precentral cortex. On immunohistochemical examination, BN were positive for phosphorylated neurofilament protein (pNFP) and αB crystallin, and some BN were positive for ubiquitin and tau protein. On double immunohistochemical staining, all pNFP-positive neurons were stained with anti-αB crystallin antibody, whereas some αB crystallin-positive BN were not stained by anti-pNFP antibody. The presence of cortical BN does not differentiate PSP from CBD, although BN are sparse in patients with PSP when cortical degeneration is not present. The results of the double immunohistochemical staining suggested that αB crystallin might be expressed earlier than pNFP in the formation of BN.