Rapidly progressive aphasic dementia with motor neuron disease: a distinctive clinical entity.

The association of motor neuron disease (MND) with rapidly progressive aphasic dementia has been recognized as a distinct clinical syndrome within the group of frontotemporal dementias (FTDs). Although the clinical and neuropsychological features of this syndrome have been defined, a small number of post-mortem studies have been published with heterogeneous neuropathological findings. We performed cognitive, neuro-imaging and neuropathological studies on a 71-year-old male with rapidly progressive aphasic dementia and MND. We initially found a selective non-fluent aphasia associated with hypoperfusion of the left frontotemporal cortex. Proton magnetic resonance spectroscopy revealed an asymmetric change of brain metabolites, with greater changes in the left temporal lobe. The bulbar manifestations of MND occurred over the following 6 months, and the patient died of bronchopneumonia. The neuropathological examination revealed loss of neurons in the hypoglossal nucleus and anterior horns of the cervical spinal cord with microvacuolation and dot-like ubiquitin-positive deposits in the frontoparietotemporal cortex, but no changes suggestive of Alzheimer's, Pick's or Lewy body disease. These findings support the conclusion that MND with rapidly progressive aphasic dementia is a distinctive clinical entity within the group of FTD-MND.