acalculia

n. Impairment in numerical abilities as a result of brain pathology. It is also known as acquired dyscalculia. The developmental defect in the normal acquisition of numerical abilities is usually referred to as developmental dyscalculia or simply dyscalculia. Two major types of acalculia can be distinguished: primary acalculia (also referred to as anarith- metia) and secondary acalculia. Primary acalculia represents a fundamental defect in understanding the numerical system. Patients present a loss of numerical concepts, inability to understand quantities, defects in using syntactic rules in calculation (e.g., “to borrow”), and deficits in correctly understanding numerical signs. The failure in calculation tasks has to be found in both oral and written operations. Secondary acalculia, on the other hand, refers to the calculation defects resulting from a different cognitive deficit (such as language defects or attention impairments). Several subtypes of secondary acalculia can be distinguished: aphasic acalculia, alexic acalculia, agraphic acalculia, spatial acalculia, and frontal acalculia.     - AA