Acalculia

Do you or your child face problems in performing simple mathematical calculations that others seem to do in a jiffy? If that is the case, it might be Acalculia at work. Find out all about this unique disorder, including its causes, symptoms, diagnosis and treatment.

What is Acalculia?

It is a type of acquired impairment in which patients experience difficulties in performing basic mathematical calculations such as addition, subtraction, multiplication or just identifying which of two given numbers have the higher value.

Acalculia Etymology

The name is derived from the Greek word “a” which means “not” and the Latin word “calculare”, meaning “to count”. Henschen came up with the term “acalculia” in the year 1925.

Acalculia and Dyscalculia

Acalculia should not be considered the same as Dyscalculia, a condition characterized by reduced ability to solve mathematical problems due to dysfunction of the brain. The former is generally acquired later in life as a result of neurological injuries, such as stroke, whereas Dyscalculia is distinct form of developmental disorder that is first observed during acquisition of numerical knowledge.

Acalculia Symptoms

Patients of acalculia demonstrate difficulty in performing simple mathematical operations, like addition, subtraction, multiplication and division.

As calculation and identification of numbers are connected with the integration of numerous cognitive skills, experts believe that an individual with this condition experiences problems in any of these four perceptions:

  • Understanding the fact that every number denotes a certain value and immediately recognizing this value
  • Recognizing the value of a number with respect to the other numbers. For example, they might face difficulty in understanding that the number 5 is greater than 3 or 6 is less than 7;
  • Determining the location of a number in a series of numbers
  • Associating the symbol of a number with its name. For example, they might face problems associating the word “three” with the symbol “3″

Young schoolchildren are usually introduced to mathematical concepts and ideas in a gradual, cumulative manner. Advancement to higher concepts requires students to grasp the basic concepts properly. The speed of grasping numerical and mathematical concepts varies among individual students. Students who find it extremely difficult to retain the basic mathematical concepts are believed to suffer from Developmental dyscalculia.

Acalculia Causes

A stroke or other associated neurological injuries can cause damage to the left angular gyrus. This can give rise to signs of computational difficulties that are commonly associated with health conditions such as Anarithmetia and Primary acalculia. However, damage caused to certain other areas of the brain of an individual can also give rise to difficulties with calculations as different types of cognitive functions are required for executing mathematical calculations. Acalculia symptoms may also be observed in patients of Alzheimer’s disease. The symptoms of this condition generally arise due to stroke, brain tumor, trauma, encephalitis or cerebral infection.

Acalculia and Parietal Lobe

The condition is linked with lesions of parietal lobe, more specifically the angular gyrus as well as the frontal lobe. Its symptoms may also be regarded as early signs of dementia. Although the disorder is occasionally considered to be a “pure” health problem, it is believed in most cases to be one of the numerous symptoms of Gerstmann’s syndrome. Gerstmann’s syndrome is a neurological condition caused by the damage of left angular gyrus. Its symptoms include agraphia, right-left confusion and finger agnosia along with the development of Acalculia.

Studies conducted in patients with parietal lobe lesions have shown the lesions of angular gyrus to be causing greater impairments in memorization of mathematical facts like multiplication tables, with rather unimpaired subtraction skills. Conversely, patients having lesions in the intraparietal sulcus region tend to experience greater difficulties in subtraction and proper multiplication abilities. These findings of double dissociations support the idea that various parts of parietal cortex are associated with different aspects of mathematical processing.

Acalculia Diagnosis

Interview sessions, where patients are asked questions about mathematical order, are among the most common screening methods for this disease. Other tests, that can accurately portray the mental condition of the patient include:

  • Memory tests
  • Confrontation naming, where the subject has to name the parts of a given object
  • Reading tests
  • Calculation tests
  • Clock drawing
  • Finger naming
  • Testing of left/right orientation
  • Writing tests
  • Spelling tests

The last four of the abovementioned tests are all conducted to confirm whether or not a patient is having Gerstmann’s Syndrome. Acalculia is one among four defining symptoms of Gerstmann’s syndrome, the other three being finger agnosia, agraphia and right/left confusion. The symptoms of Acalculia are generally seen due to the presence of Gerstmann’s syndrome although it can also be linked with certain other symptoms in some cases. It is important to note that physicians face considerable difficulty in separating mathematical disorders from damages in other parts of the brain. It is due to this reason that testing of other functions apart from mathematical calculation abilities is considered important for the diagnosis of Acalculia.

More extensive tests include:

  • Brain mapping techniques, like position emission tomography or PET
  • Event related potentials (ERP)
  • Functional magnetic resonance imaging or fMRI

These tests have proven to be highly assistive in shedding light on some of the most important anatomical aspects for numerical calculations.

A standard examination of number-related abilities among brain-damaged patients has to include both verbal as well as non-verbal elements of number processing. Certain tests can be conducted for neurological analysis:

  • Forward/backward digit span
  • Forward/backward counting
  • Symbolic transcoding, which involves reading aloud as well as taking dictation of both simple and multi-digit numerals
  • Single-digit arithmetic
  • Concrete arithmetic problems that require some planning
  • Multi-digit written calculations
  • Evaluation of numerosity of dots sets. This is either done briefly to examine estimation abilities or performed over a longer period of time to enable serial counting.

Acalculia Differential Diagnosis

As acalculia is often considered to be a symptom of Gerstmann’s syndrome (GS), it is often difficult to diagnose the former separately. On the other hand, the physician may actually diagnose GS and label the signs of Acalculia as one of the four symptoms of GS. A physician also has to look for signs of posterior parietal lobe disease. Structural and functional neuro-imaging can shed more light on any other underlying neurologic abnormalities.

Acalculia Types

There are six different forms of acalculia. These are

  • Anarithmetia
  • Agraphic acalculia
  • Alexic acalculia
  • Aphasic acalculia
  • Spatial acalculia
  • Frontal acalculia

Acalculia Treatment and Therapy

The symptoms of Gerstmann syndrome and Acalculia are not disorders but outcomes of other neurological abnormalities. Treatment for Acalculia involves cognitive rehabilitation, which may help affected individuals deal with serious symptoms that interfere with the smooth running of daily life.

Acalculia Prognosis

Patients of acalculia usually have a normal lifespan, unless other traumatic injuries or disabilities prevent normal living.

Acalculia is a numerical impairment that affects the patients late in their lives due to some stroke or brain trauma. Although it can seriously affect one’s ability to deal with numbers and make numerical calculations, patients of this condition are otherwise known to lead a normal, healthy life.

References:

http://en.wikipedia.org/wiki/Acalculia

http://www.rightdiagnosis.com/sym/acalculia.htm

http://english.turkcebilgi.com/Acalculia

http://jneurology.wordpress.com/article/acalculia-1bbsle13m97c0-110/

By   Last updated July 14th, 2012

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