Ubiquitin-positive neuronal and tau 2-positive glial inclusions in frontotemporal dementia of motor neuron type.

Attempts at classification of fronto-temporal dementias have not yet been completely successful. We report ten cases of sporadic fronto-temporal dementia (FTD) with ubiquitin-positive neuronal inclusions in cortex or in motor neurons in brain stem or spinal cord, which may contribute to the classification of FTD. Marked variation in clinical presentation as well as in pathological findings was the rule in all cases. Dementia was a prominent feature. Only one case had clinical features suggestive of motor neuron disease. Three of four younger onset cases displayed an especially severe atrophy of the temporal lobes, the basal ganglia and the substantia nigra. This contrasted with the other seven cases in which the fronto-temporal atrophy and changes in basal ganglia and substantia nigra were variable and sometimes mild. In addition to the presence of ubiquitin-reactive, but tau-and silver impregnation-negative neuronal inclusions, all cases demonstrated tau 2-positive glial inclusions, similar to those recently reported in three motor neuron disease cases with dementia. The glial inclusions were not visible with antibody to tau 1. Reaction with antibody to alpha-synuclein was invariably negative. If the combination of ubiquitin-positive neuronal and tau 2-positive glial inclusions is found to be consistently present in FTD of motor neuron type, this feature will provide a firmer basis for this diagnosis than previously available.