[A case of motor neuron disease with dementia--cerebral blood flow and cerebral oxygen metabolism].

A 51-year-old man developed muscle weakness of the bilateral upper extremities, and mental changes beginning with personality change. There was no history of mental illness in his family. A neurological examination 1 year after the onset revealed muscle atrophy and fasciculation of his bilateral upper extremities Neuropsychological examination revealed concrete speech, paraphasia, and lack of judgment. Disorientation, amnesia, dyscalculia, and spatial agnosia, however, were not recognized. These neuropsychological findings were compatible with dementia of frontal lobe type. EMG and muscle biopsy revealed neurogenic muscular atrophy. There was no abnormal findings in the brain X-CT and the brain MRI. PET study using C15O2 and 15O2 revealed reduction of cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in the bilateral medial frontal cortex, the left temporal cortex and the bilateral thalamus. From these these findings the patient was diagnosed as having motor neuron disease with dementia. Muscle atrophy and dementia worsened gradually. A second PET study 2 years and 6 months after the onset revealed severe reduction of CBF and CMRO2 in the bilateral temporal cortex and the thalamus. These PET findings suggested that dysfunction of the temporal cortex and the thalamus related to dementia in this case.