Progressive verbal apraxia of reading.

ABSTRACT

We identified a syndrome characterized by a relatively isolated progressive impairment of reading words that the patient was able to understand and repeat but without other components of speech apraxia. This cluster of symptoms fits a new syndrome designated Progressive Verbal Apraxia of Reading. A right-handed man (AB) came with a 2.5-year history of increasing difficulties in reading aloud. He was evaluated twice, 2 years apart, using multimodal neuroimaging techniques and quantitative neurolinguistic assessment. In the laboratory, reading difficulties arose in the context of intact visual and auditory word recognition as well as intact ability to understand and repeat words he was unable to read aloud. The unique feature was the absence of dysarthria or speech apraxia in tasks other than reading. Initial imaging did not reveal statistically significant atrophy. Structural magnetic resonance and FDG-PET imaging at the second assessment revealed atrophy and hypometabolism in the right posterior cerebellum, in areas shown to be part of his language network by task-based functional neuroimaging at initial assessment. This syndromic cluster can be designated Progressive Verbal Apraxia of Reading, an entity that has not been reported previously to the best of our knowledge. We hypothesize a selective disconnection of the visual word recognition system from the otherwise intact articulatory apparatus, a disconnection that appears to reflect the disruption of multisynaptic cerebello-cortical circuits.