[Diagnosis of disorders in dealing with numbers (acalculia)]

Disturbances in numeric skills (acalculia) often occur in adults following CNS damage. We present an examination procedure which assesses number-processing abilities as well as basic skills in calculation. Results of an investigation based on a unselected sample of brain-damaged adults (N = 52) show that numeric skills can be impaired in a variety of different ways. With our acalculia examination procedure it is possible to distinguish secondary forms of acalculia, which can only occur in combination with other neuropsychological disturbances, and primary acalculia, which cannot be explained as resulting from accompanying disturbances.