Acalculia

Under acalculia refers to the acquired inability to deal with numbers. ( For the development of disorder in children see dyscalculia )

Pathophysiology

The (rare ) isolated primary acalculia can occur after damage to the language-dominant ( predominantly left ) cerebral cortex. The lesion affects the parietal association cortex, for example, or lying in the region of the transition from parietal, temporal and occipital lobes gyri angular gyrus and supramarginal gyrus. Often, then, forms a so-called Gerstmann syndrome ( acalculia, Alexie, Finger-/Fußzehagnosie, right-left weakness), and / or a angularis syndrome ( acalculia, alexia, agraphia, amnesic aphasia).

Also to and leading away tracks or the area associated can be affected. In loss of function of higher visual areas may lead to an optical acalculia, deficits higher acoustic areas, however, can trigger an acoustic acalculia. The lesion parietal association areas, which lead to apraxia may result in the so-called ideational acalculia.

The computing capability also depends on other factors. Thus, a secondary acalculia also be caused by impairment of concentration, memory or language ability.

The damage can be caused by cerebral infarction, cerebral hemorrhage, brain tumors, brain injuries, brain inflammation and other tissue impairing causes.

History and classification

The designation of impairment of computing as acalculia took place in 1919 by Solomon Henschen. He differentiated the acalculia of aphasia often occurring at the same time.

The first detailed functional classification in optical, acoustic and ideational acalculia took place at the same time by Peritz. The relationship especially the ideational acalculia with apraxia often occurring at the same time it was recognized by Kleist.

Berger told 1926 acalculia in secondary acalculia as a disturbance of memory, concentration, language and literacy and primary acalculia as dyscalculia a direct without these disorders. The primary acalculia 1988 further divided by Grafman in memory impairment in the retrieval of mathematical facts and disturbances of understanding of mathematical concepts.

Case descriptions

Hécaen and colleagues described in 1961 a number of possible clinical subtypes of acalculia. They observed a alexia and agraphia for numbers with preserved recognition and writing skills for letters. Even a spatial acalculia with impaired perception multi-digit numbers with more digits was described by them.

Cohen and Dehaene 1996 could prove ( to split-brain patients) that even the non- language- dominant side of the brain to detect and use of numbers is capable of.