2023 年 19 巻 1 号 p. 63-67
Introduction: Focal brain damage can cause difficulties in counting similar items. It has been hypothesized that this visual counting disorder (VCD) is caused by an inability to recall places seen in the immediate past. However, this has not been directly tested. There also have been no studies on the impacts of VCD on patients' daily lives.
Methods: A 60-year-old, right-handed man visited our hospital complaining of difficulty counting multiple similar objects placed next to each other; for example, accounting errors caused by an inability to read multiple zeros in numbers in sales receipts. This patient had the problem for 25 years, since an infarction in the right temporoparietal region after a subarachnoid hemorrhage. To test the recall hypothesis, we performed a visual counting test on the patient and healthy control subjects. Circles were presented under two conditions: static (rows of circles presented vertically, centered on the screen) and dynamic (rows of circles presented by scrolling vertically). Subjects were asked to count and report numbers of circles as soon as each row appeared.
Results: Under the static condition, the patient showed a significantly longer reaction time and more frequent gaze retentions than did the control subjects; however, no differences were observed under the dynamic condition.
Conclusion: These findings directly support the hypothesis. Our patient's compensatory methods might be useful to other patients.
