We report a 85-year-old woman who developed speech disturbance and left hemiparesis. She had a gradual onset of gait disturbance 3 years prior to the present admission. Five days before admission, she started to pace up and down in her house; she did not want to take food on the following day, and she developed fever of 39 degrees C; it was also noted that she became mute. On the next day, she developed left hemiparesis; she was still mute but was able to communicate by hand writing to some extent. She was admitted to our service on February 24, 1992. On admission, she was alert but mute; her body temperature was 37.1 degrees C, and her BP 110/70 mmHg. The lungs were clear and general physical examination was unremarkable. Neurologic examination revealed that she did not utter even a word. She was unable to understand examiner's simple questions; communication by hand writing was also difficult, but she could draw her name and a circle; repetition was also impaired. Examination of other higher cerebral functions such as praxis and gnosis was impossible. Her optic fundi were unremarkable; no anisocoria was noted; extraocular muscles appeared intact, and the vestibulo-ocular reflex was normally elicited. The nasolabial fold was shallower on the left; the tongue showed a slight deviation to the left. She had near complete spastic left hemiplegia; deep tendon reflexes were increased bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)