Pure Prosodic Type of Primary Progressive Apraxia of Speech Mimicking Nonfluent Aphasia and Later Progressing to Corticobasal Syndrome.

Primary progressive apraxia of speech (PPAOS), a rare neurodedegenerative disorder, can be subdivided into predominant phonetic or prosodic type. Pure prosodic type of PPAOS as an isolated disorder has been hardly found. We present 2 cases of patients with pure prosodic PPAOS who initially were misdiagnosed as nonfluent variant of primary progressive aphasia and later turned out to be corticobasal syndrome. A 65-year-old woman and a 72-year-old man were referred to our speech-language clinic under the clinical impression of nonfluent variant of primary progressive aphasia. The neurological examinations revealed no definite abnormalities except for slow and effortful speech with the production of simple sentences. However, their receptive and expressive language abilities were normal. Their brain magnetic resonance imaging was unremarkable. We initially entertained the diagnosis of pure prosodic type of PPAOS. During several years of follow up, they gradually developed extrapyramidal symptoms which are compatible with corticobasal syndrome. The characteristics of the patients and the results of neuroimaging studies are discussed.