Acalculia is a generalizing concept that includes a variety of violations of the understanding of numbers and performing arithmetic operations. It is manifested by visual / auditory unrecognition of numbers, misunderstanding of the concept of number, numeric digit, inability to consistently perform calculations. It is diagnosed on the basis of clinical features, the results of neurological, psychiatric examination, arithmetic testing, cerebral tomography. Treatment is carried out in relation to the underlying disease, rehabilitation includes special classes to restore arithmetic abilities.
R48.8 Other and unspecified violations of recognition and understanding of symbols and signs
The existence of a special counting center in the human brain was described at the beginning of the XIX century. At first, doctors assumed that it was located in the frontal lobe, then determined its localization at the junction of the parietal and occipital lobes of the dominant hemisphere. In 1926, the German physiologist Hans Berger proposed the term “primary acalculia” to denote counting disorders caused by direct damage to the counting center, to distinguish pathology from secondary disorders observed as a result of other cortical dysfunctions. Counting disorders in children are partial in nature, often are the result of underdevelopment of cognitive abilities, therefore, in practical neurology they are designated by the term “dyscalculia”.
Various forms of pathology are associated with damage to the cortex of the parietal, occipital, temporal, and frontal lobes of the brain. The main etiofactors leading to pathological changes in the cerebral cortex are:
- Cerebrovascular pathology. Acalculia can occur in acute violation of cerebral blood flow (ischemic, hemorrhagic stroke), with chronic cerebral ischemia, leading to gradually increasing vascular dementia.
- Traumatic brain injuries. Calculation disorders are associated with brain contusion, accompanied by the formation of hematomas, areas of brain matter crushing with the involvement of areas of the cortex that are involved in the counting process.
- Neuroinfections. Along with other cognitive disorders, acalculia accompanies variable etiology encephalitis, meningoencephalitis, encephalomyelitis.
- Intoxication. Lesions of the cerebral cortex are possible with acute poisoning, chronic intoxication, including those caused by dysmetabolic processes (hyperglycemia, uremia).
- Brain tumors. Convexital neoplasms (gliomas, meningiomas), intracerebral tumors that germinate or compress the cortex lead to the loss of cortical functions.
- Degenerative diseases of the central nervous system: Creutzfeldt-Jakob disease, leukodystrophy, Alzheimer’s disease. Acalculia is caused by progressive atrophy of the cerebral cortex.
Childhood acalculia is more often associated with brain development abnormalities, perinatal pathology (fetal hypoxia, intrauterine infection, intracranial birth trauma), hereditary diseases and dysmetabolic syndromes.
Counting is a complex multi-level function of the higher nervous activity of a person. The center of the account is closely connected with other zones of the cortex, without the participation of which its full functioning is impossible. Visual “recognition” of numbers occurs due to the work of the visual cortex of the occipital lobe, auditory — due to the functioning of the auditory center of the cortex, localized in the upper temporal gyrus.
The recognition of numbers, the execution of calculations is carried out with the participation of memory, requires a certain concentration of attention. The solution of the simplest mathematical problems occurs under the control of the frontal cortex, responsible for the ability to perceive abstract concepts, to carry out purposeful activities.
Etiological factors trigger diffuse or local vascular, inflammatory, post-traumatic, dystrophic processes in the structures of the cerebral cortex, leading to degeneration and death of neurons. Acalculia occurs when cortical zones involved in the implementation of the counting function are involved in the pathological process. The defeat of the counting center is extremely rarely isolated, in most cases it is combined with other cognitive disorders.
Taking into account the mechanism of occurrence, acalculia is classified into two main forms: primary and secondary. Primary (specific) acalculia is caused by pathological processes in the area of the counting center at the junction of the occipital and parietal lobes of the dominant hemisphere. Secondary (nonspecific) acalculia occurs when other areas of the cortex involved in the complex counting process are affected, there are four types:
- Optical — a violation of visual perception of numbers. It develops in pathology of the occipital regions of the cerebral cortex. Accompanies visual agnosia.
- Sensory (auditory) — caused by a disorder of recognition of sounds and speech. It is associated with a lesion of the superior temporal gyrus, combined with sensory aphasia.
- Acoustic-mnestic (amnestic) — the basis of the disorder is a disorder of auditory-speech memory in pathological processes in the temporal cortex. Accompanied by other memory disorders.
- Frontal — operations with numbers are impossible due to disorders of the organization and control of purposeful activity (praxis). Other manifestations of apraxia are observed.
Clinical manifestations vary depending on the form of pathology. Primary acalculia is characterized by a lack of understanding of the concept of number, numerical digits (for example, patients do not see the difference between the numbers 152 and 125), the impossibility of comparing numbers, carrying out the simplest arithmetic calculations. It is combined with spatial agnosia that occurs when the parietal region is affected, manifested by a violation of the orientation “right-left”, “top-bottom”, perception of the coordinate system, etc.
Secondary acalculia is detected in combination with other cognitive disorders: agnosia, apraxia, aphasia, amnesia. The optical form is manifested by the absence or errors of recognition of the numbers depicted. Patients cannot name the number they saw, they confuse figures similar in pattern (7 and 1, 9 and 6). The concept of numbers, the perception of numbers by ear, the ability to perform counting operations in the mind is preserved. Typical symptoms of visual agnosia are non—recognition of letters, faces, images of objects. Dysgraphy and dyslexia are noted.
Sensory acalculia accompanies auditory agnosia — a violation of the recognition of sounds, elements of speech. Patients do not understand what they have heard, they talk a lot, with rearrangement of syllables, repetitions, mistakes. Reading numbers, understanding arithmetic calculations read suffer to a lesser extent. The acoustic-mnestic form is associated with a disorder of the volume of perception of numbers, images-representations, difficulty remembering numbers by name. It is characterized by an increase in the number of errors in writing numbers under dictation with an increase in the speed of their submission, a large volume of tasks, increased noise. Counting is difficult, the concept of numbers, digits, account structures are preserved.
Frontal acalculia manifests itself in the structure of apraxia. The violation concerns the sequence of performing mathematical calculations along with the disorder of activity in solving any assigned tasks. The patient has an automated account within a dozen, an understanding of prime numbers, a multiplication table, but cannot operate with multi-digit numbers, make up a number according to the proposed numbers, find the composition of a number, solve an example with prime numbers in several actions. Changes in the psycho-emotional sphere are noted: impulsivity, lability, stereotyping, aggressiveness, disturbed behavior.
Since acalculia is a part of complex disorders of the cognitive sphere, its isolation among the leading intellectual and mnestic disorders presents a certain diagnostic complexity. Another task is to determine the form of pathology, diagnosis of the underlying disease, the manifestation of which was acalculia. The following diagnostic techniques are used:
- Anamnesis collection. Allows you to find out how the disease began and developed, what was provoked.
- Study of neurological status. Examination by a neurologist makes it possible to identify focal symptoms, suggest localization of cerebral lesion. In children, the examination includes an assessment of the level of mental development. Patients with TBI, intracranial tumors are additionally consulted by a neurosurgeon.
- Examination by a psychiatrist. It is necessary for patients with mental disorders, helps to differentiate cognitive disorders from mental illnesses.
- Arithmetic testing. Aimed at diagnosing the form of acalculia. It includes the study of visual and auditory understanding of numbers, the ability to memorize numbers, and perform calculations.
- MRI brain. Neuroimaging reveals morphological changes characteristic of the underlying disease: post-traumatic hematomas, intracerebral tumors, foci of inflammation, stroke zone, degenerative processes. In the case of cerebrovascular pathology, ultrasound, MRI of cerebral vessels is prescribed.
Therapy is aimed at relieving the etiopathogenetic mechanisms of the underlying disease, the subsequent restoration of lost neurological functions, including the ability to operate with numbers. Treatment is carried out in stages.
Drug therapy of the underlying disease:
- Correction of cerebral hemodynamics. For intracranial hemorrhages, antifibrinolytics (gamma-aminocaproic acid), angioprotectors (calcium preparations, sodium ethamzylate) are used, for cerebral ischemia — vasodilators (vinpocetine), microcirculation-improving agents (pentoxifylline), thrombolytics (nadroparin).
- Neurometabolic therapy. It is carried out in various volumes for almost any cerebral lesions. It includes nootropics, amino acids, antioxidants, combined remedies.
- Prevention of cerebral edema. Diuretic pharmaceuticals are prescribed, with the threat of edema, drip administration of osmodiuretics is carried out.
- Psychotropic drugs. Sedatives, tranquilizers, neuroleptics are used according to indications for the relief of psychomotor agitation, emotional lability, aggressiveness.
- Etiotropic therapy of infections. Required for patients with infectious brain damage, produced in accordance with the established nature of the pathogen (bacterial, viral, parasitic).
- Arithmetic classes. They must fully comply with the structure of the detected violations. Various techniques include using cards with numbers, restoring representations of numerical digits, pronouncing numbers, performing arithmetic operations.
- Psychotherapy. Psychotherapeutic help is necessary to correct the patient’s attitude to the problems of the intellectual sphere that have arisen, to form a positive attitude to rehabilitation classes.
- Speech therapy classes. They are indicated for auditory agnosia. They are carried out by a speech therapist as part of the correction of aphasia.
In the case of an acute process (stroke, encephalitis, TBI), pharmacotherapy is carried out first, rehabilitation is carried out after the acute condition is relieved. In the chronic course of the underlying pathology (chronic cerebral ischemia, degenerative lesions of the central nervous system), drug therapy is combined with restorative. Radical neurosurgical treatment is indicated for patients with intracranial neoplasms.
Prognosis and prevention
Acalculia is a separate symptom in the structure of the basic pathology of the brain, its prognosis is inextricably linked with the nature and course of the underlying disease. Correct therapy and the young age of the patient ensure 100% recovery of the counting function after trauma, encephalitis, acute intoxication, lacunar stroke. Persistent acalculia negatively affects the quality of life of the patient, worsens his social adaptation.
Prognostically unfavorable factors are cerebral anomalies, old age, the vastness of the affected area, the impossibility of radical removal of the tumor process, the steady progression of degenerative pathology. Prevention is reduced to the prevention of TBI, infectious diseases, perinatal pathology, toxic lesions, timely treatment of cerebrovascular diseases.