Globular glial tauopathy Type II: Clinicopathological study of two autopsy cases

Globular glial tauopathies (GGTs) are four-repeat tauopathies characterized by the presence of two types of tau-positive globular glial inclusions (GGIs): globular oligodendrocytic and astrocytic inclusions (GOIs and GAIs). GGTs are classified into three different neuropathological subtypes: Types I, II and III. We report two patients with GGTs - a 76-year-old woman and a 70-year-old man - in whom the disease duration was 5 and 6 years, respectively. Both patients exhibited upper and lower motor neuron signs and involuntary movements, and the latter also had dementia with frontotemporal cerebral atrophy evident on magnetic resonance imaging. Neuropathologically, in both cases, the precentral gyrus was most severely affected, and at the gray-white matter junction there was almost complete loss of Betz cells and occurrence of GOIs and coiled bodies with numerous neuropil threads. Both patients also showed neuronal loss and GGIs (mostly GOIs) in many other central nervous system regions, including the basal ganglia. Apart from the degree of regional severity, the distribution pattern was essentially the same in both cases. However, GAIs were not conspicuous in any of the affected regions. Based on the morphology and distribution pattern of the GGIs, we diagnosed the present two patients as having GGT Type II. Electron microscopic and biochemical findings in the former were consistent with the diagnosis. Type II cases are reported to be characterized by pyramidal features reflecting predominant motor cortex and corticospinal tract degeneration. The present observations suggest that a variety of neurological features, including dementia, can occur in GGT Type II reflecting widespread degeneration beyond the motor neuron system.