[Reappraisal of amyotrophic lateral sclerosis with dementia]

Amyotrophic lateral sclerosis (ALS) with dementia is characterized by rapidly progressive dementia and motor neuron involvement. The age at onset in 12 sporadic cases ranged from 43 years to 78 years. The initial symptoms are dementia, such as uninhibited behavior and personality change in most patients. Both dementia and motor neuron involvement appear within 1 or 2 years of the onset. The clinical picture of motor neuron disturbance was bulbar-type ALS. In ALS-dementia, lower motor neuron sign is predominant than upper motor neuron sign. The pattern of dementia indicated impaired frontal lobe function, confirmed by frontal sign such as perseveration, forced grasping and utilization behavior. These neurological signs are significant in association with the frontal lesion on CT, MRI and single photon emission computed tomography. The pathological findings show frontotemporal atrophy, mild non-specific neuronal loss of cortical superficial layer, fibrous gliosis of subcortical white matter, degeneration of substantia nigra and motor neuron involvement. The clinicopathological findings resembled those of dementia of frontal type and are distinct from those of Alzheimer's disease. We thus consider that the combination of motor neuron disease and dementia is a new clinicopathological entity, quite distinct from ALS or other dementias, as Yuasa and Mitsuyama proposed earlier.