[A case of dementia with motor neuron disease associated with agraphia--the omission of kana letters].

We report a 55-year-old right-handed Japanese man with motor neuron disease and dysgraphia of kana letters. He was admitted to our hospital because of dysarthria and dysphasia. On admission, the results of general physical examination were within normal limits. Neurological examination revealed severe dysarthria, dysphasia, impaired movement of the tongue without fasciculation and slight distal muscle weakness in the bilateral upper limbs. There were no fasciculation of the muscle. Deep tendon reflexes were hyperactive without Babinski's signs. Sensation, coordination, and gait were normal. Neurophysiological studies demonstrated normal motor nerve conduction velocities and sensory action potential. The results of needle electromyography of the upper limbs were compatible with motor neuron disease (MND). Magnetic resonance imaging (MRI) showed atrophy of the bilateral temporal region of the brain. 99mTc-HMPAO SPECT (Single Photon Emission Computed Tomography) showed reduced uptake of tracer in the bilateral temporal region. On neuropsychological examination, his behavior was normal, and orientation and intelligence were also preserved, but his speech was severely impaired. Reading comprehension was slightly impaired. In regard to writing comprehension, he had no difficulty in copying of words though dictation was found to be impaired. He omitted one kana letter in a word. Agraphia is accompanied by various factors such as aphasia, dementia, agnosia, alexia. But in this case at least for early stage, agraphia existed without other higher cortical dysfunction. He did not show severe dementia in his early stage of his disease, but developed it later in the disease's progression. In this case, agraphia might be due to the atrophic changes in the temporal lobe.