[A case of motor neuron disease with dementia, presenting motor aphasia as an initial symptom].

We report a case of motor neuron disease (MND) with dementia, presenting motor aphasia as an initial symptom. A 67-year-old man was admitted to our hospital because of speech disturbance slowly progressing for 2 years. On physical examination, he showed no neurological abnormalities except for non-fluent aphasia and increased deep tendon reflexes without laterality. MRI demonstrated bilateral fronto-temporal atrophy, dominating the left hemisphere. This finding was confirmed by surface anatomy scanning (SAS), showing an obvious atrophy in the left inferior frontal gyrus, compared with the right one. SPECT with 123I-IMP revealed some irregular defects in the bilateral frontotemporal region. Because he showed dementia, bulbar palsy with tongue atrophy, weakness of upper extremities and facial muscles, snout reflex, and the atrophy and fasciculation in limbs in addition to motor aphasia soon after the discharge from our hospital, he was diagnosed as having MND with dementia. At age 68, he died of a respiratory failure 3 years after the onset of the disease. MND with dementia seldom shows motor aphasia as an initial symptom. We must include, however, the MND with dementia as an differential diagnosis when we see the patients with progressive aphasia.