Difficulties of clinical diagnosis in primary progressive aphasia. Clinical observation

Primary progressive aphasia is a syndrome characterized by progressive speech dysfunction. There are three types of this condition. The first — agrammatic — type of primary progressive aphasia is typical for frontotemporal dementia and characterized by progressive worsening of speech during several years without other neurological symptoms. For this type, alexia is typical (can be present before the onset of other clinical symptoms) along with agraphia and oral apraxia.

Second type of primary progressive aphasia, semantic aphasia, may also be present in frontotemporal dementia.

The third type of primary progressive aphasia is a logopenic variant which is a manifestation of the atypical variant of Alzheimer’s disease. In this type, the speech disorders are prevailing over the mnestic manifestations. Differential diagnosis in that case is difficult given lack of specific markers in patients with Alzheimer’s disease.

As a clinical illustration, we present a case of a 50-year-old patient. She has been considering herself ill from the age of 45 years, when her speech impairment emerged and started to progress; she also started to experience difficulties in recalling and correct pronunciation of the words. No significant pathologies in internal organs were identified. Her neurological examination showed pyramidal insufficiency more on the right, slight muscle rigidity in the limbs, acheirokinesis, and mild ataxia. Examination of patient’s higher cerebral functions showed mixed aphasia (amnestic and motor), frequent agrammatisms, paraphasias, anomias, apraxia more in the left arm, simultaneous agnosia, partial hemispatial neglect of the left side, alexia, agraphia, acalculia, and finger agnosia. Frontal Assessment Battery test score was 8 and Mini Mental State Examination score was 16. Vascular, infectious, metabolic, autoimmune, tumorous, and iatrogenic causes of dementia have been ruled out. Speech disturbances were typical for agrammatic variant of primary progressive aphasia, but didn’t contradict with logopenic type of Alzheimer’s disease. The PET scan showed no hemispheric asymmetry. We suggested that the most probable diagnosis could be primary progressive aphasia, which can be a manifestation of both frontotemporal dementia and Alzheimer’s disease. Moreover, the differential diagnosis based on clinical manifestations only, without specific PET investigation or specific CSF study is rather difficult.