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. 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. 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. The patient would make errors such as combing their hair with the wrong side of the comb or placing a pistol in his mouth. 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. 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. 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.
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. 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. 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. 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. 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.
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. Overall, IA is an autonomous syndrome, linked to damage in the left hemisphere involving semantic memory disorders rather than a defect in motor control. 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. 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.
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