["Progressive acalculia": a variety of focal degenerative atrophy affecting number processing].

A 72-year-old man experienced increasing difficulties in calculating and processing numbers. He made many syntactic errors when he read and wrote numbers, both in arabic and number-word forms. Transcoding between arabic numerals and number-words was severely impaired. His calculation abilities were grossly impaired. He could not perform even simple multiplications, but additions and subtractions were preserved. He was unable to recite multiplication tables or the alphabet. In contrast, numerosity judgment, magnitude comparisons,and semantic evaluation of numbers were intact. The patient's deficit could be summarized as an Impairment in all tasks involving numbers in a verbal format, corresponding to the so-called "verbal anarithmetia'." It was noteworthy that verification of operations, including multiplications, was accurately performed. For example, the patient could not solve a multiplication like 8 x 9, but could estimate that 9 x 2=1 1 was closer to the exact result than 9 X 2=17, or could state that 8 x 2=16 was exact even though, at the same time, he expressed verbally the terms of the corresponding addition "eight plus two is ten." Other cognitive deficits were detected by neuropsychological tests which demonstrated mainly anomic aphasia, dysorthographic agraphia without alexia, impairment of short term and episodic memory, digital agnosia. However, the patient could not be considered to have demon-eti due to preserved self-sufficiency, except for tasks requiring calculation abilities. During the two years of follow-up, the impairment in processing numbers and calculation remained predominant over other deficits. Cerebral MRI showed an atrophy of the left temporal and parietal lobes, and SPECT study showed a reduction of regional cerebral blood flow of the left hemisphere. This original clinical presentation of a cerebral degenerative disease could be described as "primary progressive acalculia" whatever the underlying primary pathological process.