Ideational apraxia

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Ideational apraxia (IA) is a neurological disorder which explains the loss of ability to conceptualize, plan, and execute the complex sequences of motor actions involved in the use of tools or otherwise interacting with objects in everyday life. [1] Ideational apraxia is a condition in which an individual is unable to plan movements related to interaction with objects, because they have lost the perception of the object's purpose. [2] Characteristics of this disorder include a disturbance in the concept of the sequential organization of voluntary actions. The patient appears to have lost the knowledge or thought of what an object represents. This disorder was first seen 100 years ago by Doctor Arnold Pick, who described a patient who appeared to have lost their ability to use objects. [3] The patient would make errors such as combing their hair with the wrong side of the comb or placing a pistol in his mouth. [3] From that point on, several other researchers and doctors have stumbled upon this unique disorder. IA has been described under several names such as, agnosia of utilization, conceptual apraxia or loss of knowledge about the use of tools, or Semantic amnesia of tool usage. [4] The term apraxia was first created by Steinthal in 1871 and was then applied by Gogol, Kusmaul, Star, and Pick to patients who failed to pantomime the use of tools. [3] It was not until the 1900s, when Liepmann refined the definition, that it specifically described disorders that involved motor planning, rather than disturbances in the patient’s visual perception, language, or symbolism. [4] [5]

Contents

Signs and symptoms

Liepmann was the first to actually conduct tests on these patients in his laboratory. These tests are known as multiple-object tasks or MOT. [5] Each task requires the patient to use more than one object; the researcher describes a task to the patient and asks them to execute that task as described. Liepmann gave the patients all the necessary articles, such as a candle and a matchbox, which were placed before the patient. He then observed the patients to see how they interacted with each object. [5] In the case of the matchbox, one patient brought the whole box up next to the wick, instead of just one match. Another opened the box and withdrew a match, then brought it to the wick unlighted. Still another patient struck the candle against the striking surface on the matchbox. Thus Liepmann was able to witness the discontinuity of the patients' actions with respect to everyday objects and to categorize the errors that the patients made, namely: mislocation of actions, object misuse, omissions, perplexity, and sequence errors. [6]

Even though afflicted persons are unable to correctly perform simple tasks using multiple items as provided, they are able to accurately identify the objects involved in simple tasks. For example, they are able to match a given sequence of photographs with the correct label, such as: the process of making coffee, buttering bread, or preparing tea. These patients are also able to successfully identify objects when a researcher verbally describes the function of the tool. Another test involves matching the appropriate object with its function. Finally, the fact that patients can identify the actions of a given tool from a sequence of photographs, shows that they completely understand object usage. [7]

The deficit is therefore not that patients lack the knowledge of how to use an object; they fully understand the function of each tool. Rather, the problem lies in that, when they attempt to interact with the tools (in a multiple-object task) in order to execute those functions, that execution is flawed. [6]

Cause

The cause of IA is still somewhat of a mystery to most researchers because there is no localized focal point in the brain that shows where this deficit will occur. Since 1905 Liepmann proposed a hypothesis of an action processing system that is found in the left hemisphere of the brain, which is dedicated to skilled, motor planning that guides the movement of the body. Yet, he still was never able to produce two patients with the same brain damage that showed ideational apraxia. The major ideas of where IA is found are in the left posterior temporal-parietal junction. Possibly damage to the lateral sulcus also known as Sylvian fissure may contribute to an individual’s deterioration of object recognition. Another possible area of damage leading to IA is the submarginal gyrus, which is located in the parietal lobe of the brain. [8] Overall, IA is an autonomous syndrome, linked to damage in the left hemisphere involving semantic memory disorders rather than a defect in motor control. [9]

Several severe injuries or diseases can cause IA in a wide range of patients. Alzheimer's patients are the largest cohort groups that express IA. [10] Other groups that are often seen with this dysfunction are stroke victims, traumatic brain injuries, and dementia. The damage is almost always found in the dominant hemisphere (i.e. usually the left hemisphere) of the patient.[ citation needed ]

Pathophysiology

Ideational apraxia is characterized by the mechanism that the patient loses the “idea” of how they should interact with an object. Norman and Shallice came up with the dual-systems theory of the control of routine and willed behavior. According to this theory one system –contention scheduling is responsible for the control of routine action, while – supervisory attention is able to bias this system when willed control over the behavior is required. [6]

Contention scheduling is a complicated set of processes that involve action schemas. [6] These action schemas are what are used in the sequence of actions involved in making a cup of tea and situation specific factors such as whether a glass of lemonade is too bitter. Even simple tasks need the monitoring of goals: e.g., has sugar been added to a cup of coffee.[ citation needed ]

But as we learn new activities we are also learning new schemas. We all know how to open a jar of jelly or how to light a match. Schemas are needed in everyday life because they give purpose and goal to our behaviors. In each schema there are subgoals or components that make up the schema. [6] An example would be the schema of lighting a match. There are three subgoals found in this schema: holding the match, holding the matchbox, and holding a lit match. More subgoals could be applied but those are the most obvious when the overall goal wanted is to light a match. That is why schemas form a hierarchy, with the more complicated and complex action sequences corresponding to high level schemas and low level schemas correlating with simple single object tasks. [6]

As said earlier from Norman and Shallice the other component used in voluntary action is supervisory attention. Schemas cause the activation of behaviors; the greater the excitation of the activity the more easily it is to achieve the subgoals and complete the schema. Either top-down fashion activates schemas, where intentions are governed by some type of cognitive system, or by bottom-up fashion where features or an object in the environment trigger a schema to begin. The bottom-up feature is what is seen in ideational apraxia because an object appears to capture the attention of the patient. [6] However, the schema that corresponds to the object cannot be fulfilled. For some reason there is a disconnect in the brain that does not allow the individual to produce the sequence of actions that they know should be happening with the object that is in their visual pathway. It is this area that is still an area of ambiguity to physicians and researchers alike. They are not sure where in the brain the action schema pathway is severed. [6]

Diagnosis

Ideational apraxia is difficult to diagnose. This is because the majority of patients who have this disorder also have some other type of dysfunction such as agnosia or aphasia. The tests used to make an IA diagnosis can range from easy single-object tasks to complex multiple-object tasks. [11] When being tested, a patient may be asked to view twenty objects. They then have to demonstrate the use of each single object following three different ways of presenting the stimuli. The patient must then perform a complex test in which the examiner describes a task such as making coffee and the patient must show the sequential steps to make a cup of coffee. The patients are then scored on how many errors are seen by the examiner. The errors of the patients in performing the MOT were scored according to a set of criteria partly derived from De Renzi and Lucchelli. [7]

Error classes

Two classes of errors are used to develop a diagnosis:

Class I: Sequence errors

Class II: Conceptual errors

  1. (Mis1) involves a well-performed action that is appropriate to an object different from the object target (e.g., hammering with a saw);
  2. (Mis2) involves an action that is appropriate at a superordinate level to the object at hand but is inappropriately specified at the subordinate level (e.g., cutting an orange with a knife as if it were butter).
  1. (Misl1) is an action that is appropriate to the object in hand but is performed in completely the wrong place (e.g., pouring some liquid from the bottle onto the table rather than into the glass);
  2. (Misl2) involves the correct general selection of the target object on which to operate with the source object or instrument in hand but with the exact location of the action being wrong (e.g., striking the match inside the matchbox).

As the examiner observes the patient for each task they mark off which errors were committed. From these criteria the examiner will be able to focus on severity of the dysfunction. It is important to express that the motor movement is not lost in patients with IA. Yet, at first glance their movements may appear to be awkward because they are unable to plan a sequence of movements with the given object. [7]

Therapy

Since the underlying cause of the disorder is damage to the brain, at present ideational apraxia is not reversible. However, Occupational or Physical Therapy may be able to slow the progression and help patients regain some functional control, with the treatment approach being the same as that of ideomotor apraxia. [12] Some recovery may occur in younger patients after stroke, because brain plasticity may allow the functions of these damaged regions to be remapped. As patients develop new behaviors to cope with their apraxia, their brain's functioning neurons may take on some of the functions of the dead or damaged regions. [10]

In the context of dementia, apraxia is a major cause of morbidity, and progresses with the underlying disease sometimes to the extent that patients may be unable to feed themselves or use simple utensils. Patients often become highly dependent or require nursing home placement because of their inability to properly use objects.

Brain imaging techniques such as fMRI, EEG, and PET scans may help in understanding the neuroanatomical and computational basis of ideational apraxia. Understanding these mechanisms is likely to be crucial in developing new modes of therapy to help patients cope with their disorder.

Related Research Articles

<span class="mw-page-title-main">Aphasia</span> Inability to comprehend or formulate language

In aphasia, a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine but aphasia due to stroke is estimated to be 0.1–0.4% in the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases.

<span class="mw-page-title-main">Expressive aphasia</span> Language disorder involving inability to produce language

Expressive aphasia, also known as Broca's aphasia, is a type of aphasia characterized by partial loss of the ability to produce language, although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have more grammatical significance than physical meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.

<span class="mw-page-title-main">Receptive aphasia</span> Language disorder involving inability to understand language

Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities and effortless speech output. Writing often reflects speech in that it tends to lack content or meaning. In most cases, motor deficits do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke's aphasia are typically unaware of their errors in speech and do not realize their speech may lack meaning. They typically remain unaware of even their most profound language deficits.

<span class="mw-page-title-main">Apraxia</span> Medical condition

Apraxia is a motor disorder caused by damage to the brain, which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorder's severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty. Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimer's disease, brain tumor, or other neurodegenerative disorders. The multiple types of apraxia are categorized by the specific ability and/or body part affected.

<span class="mw-page-title-main">Agnosia</span> Medical condition

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<span class="mw-page-title-main">Cognitive neuropsychology</span>

Cognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. Cognitive psychology is the science that looks at how mental processes are responsible for the cognitive abilities to store and produce new memories, produce language, recognize people and objects, as well as our ability to reason and problem solve. Cognitive neuropsychology places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to inferring models of normal cognitive functioning. Evidence is based on case studies of individual brain damaged patients who show deficits in brain areas and from patients who exhibit double dissociations. Double dissociations involve two patients and two tasks. One patient is impaired at one task but normal on the other, while the other patient is normal on the first task and impaired on the other. For example, patient A would be poor at reading printed words while still being normal at understanding spoken words, while the patient B would be normal at understanding written words and be poor at understanding spoken words. Scientists can interpret this information to explain how there is a single cognitive module for word comprehension. From studies like these, researchers infer that different areas of the brain are highly specialised. Cognitive neuropsychology can be distinguished from cognitive neuroscience, which is also interested in brain-damaged patients, but is particularly focused on uncovering the neural mechanisms underlying cognitive processes.

<span class="mw-page-title-main">Parietal lobe</span> Part of the brain responsible for sensory input and some language processing

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<span class="mw-page-title-main">Bálint's syndrome</span> Medical condition

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<span class="mw-page-title-main">Hugo Liepmann</span> German neurologist and psychiatrist

Hugo Karl Liepmann was a German neurologist and psychiatrist born in Berlin, into a Jewish family.

Ideomotor Apraxia, often IMA, is a neurological disorder characterized by the inability to correctly imitate hand gestures and voluntarily mime tool use, e.g. pretend to brush one's hair. The ability to spontaneously use tools, such as brushing one's hair in the morning without being instructed to do so, may remain intact, but is often lost. The general concept of apraxia and the classification of ideomotor apraxia were developed in Germany in the late 19th and early 20th centuries by the work of Hugo Liepmann, Adolph Kussmaul, Arnold Pick, Paul Flechsig, Hermann Munk, Carl Nothnagel, Theodor Meynert, and linguist Heymann Steinthal, among others. Ideomotor apraxia was classified as "ideo-kinetic apraxia" by Liepmann due to the apparent dissociation of the idea of the action with its execution. The classifications of the various subtypes are not well defined at present, however, owing to issues of diagnosis and pathophysiology. Ideomotor apraxia is hypothesized to result from a disruption of the system that relates stored tool use and gesture information with the state of the body to produce the proper motor output. This system is thought to be related to the areas of the brain most often seen to be damaged when ideomotor apraxia is present: the left parietal lobe and the premotor cortex. Little can be done at present to reverse the motor deficit seen in ideomotor apraxia, although the extent of dysfunction it induces is not entirely clear.

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Executive functions are a cognitive apparatus that controls and manages cognitive processes. Norman and Shallice (1980) proposed a model on executive functioning of attentional control that specifies how thought and action schemata become activated or suppressed for routine and non-routine circumstances. Schemas, or scripts, specify an individual's series of actions or thoughts under the influence of environmental conditions. Every stimulus condition turns on the activation of a response or schema. The initiation of appropriate schema under routine, well-learned situations is monitored by contention scheduling which laterally inhibits competing schemas for the control of cognitive apparatus. Under unique, non-routine procedures controls schema activation. The SAS is an executive monitoring system that oversees and controls contention scheduling by influencing schema activation probabilities and allowing for general strategies to be applied to novel problems or situations during automatic attentional processes.

Body part as object (BPO) mime gestures occurs when an individual substitutes a part of their body - usually arms, fingers, or hands - to be part of an object they are miming. Miming uses representational gestures, meaning they are used to convey a message to others without the use of speech. A commonly used example of BPO miming is demonstrated by an individual using their finger to represent a toothbrush while acting out brushing their teeth.

References

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