Apraxia is a neurological disorder characterized by the loss of the ability to execute skilled movements and gestures, despite having the desire and the physical ability to perform them. Unlike paralysis, movements remain intact but the patient can no longer combine movements sequentially to perform desired functions e.g. dressing. Apraxic patients are unable to perform skilled motor acts because their motor engrams (programs) that guide skilled acts have either been lost or cannot be accessed. The disturbance of purposeful movements cannot be termed apraxia if it results from a language comprehension disorder, dementia or if the patient suffers from any straightforward motor or sensory deficit (i.e paresis, dystonia, ataxia) that could fully explain the abnormal motor behavior.
CAUSES: Apraxia results from dysfunction of the cerebral hemispheres of the brain, especially the parietal lobes. Damage to the parietal lobes can arise from a variety of diseases/causes including: stroke (higher prevalence in left-sided vs. right-sided), metabolic diseases, head injuries, Alzheimer’s disease, Parkinson’s disease, supranuclear palsy, Huntington’s disease.
DIAGNOSIS: When diagnosing apraxia, looking for the presence of other symptoms is usually the first step, for example: muscle weakness or difficulties with language comprehension, as both are indicative of other conditions and their presence would help rule out apraxia. An MRI of the brain may also be useful to determine the extent and location of possible brain damage.
TREATMENT & PROGNOSIS: If apraxia is a symptom of another disorder, the underlying disorder is treated first and then depending on the type of apraxia, either physical, speech, or occupational therapy is implemented. The prognosis for patients with apraxia varies and depends partly on the underlying cause. Some patients improve significantly while others may show very little improvement.
EFFECTS OF APRAXIA ON OCCUPATIONAL PERFORMANCE:
Dressing – A patient may put his underwear on top of his pants, exhibiting difficulty with sequencing.
Grooming – A patient may use a tube of toothpaste to brush his teeth instead of a toothbrush.
Toileting – A patient may forget how to use the toilet paper that is in front of him appropriately.
Eating – Patients with apraxia may misuse a utensil (use a spoon as a straw). The patient may also have difficulty with spatial movements, so he would have trouble successfully moving a utensil to his mouth without spilling.
Meal preparation – Apraxia results in difficulties with the sequencing required to successfully prepare a meal.
Mobility & Functional Transfers: A patient may forget how to appropriately use a mobility device. For example, he may try to put the brakes on his wheelchair by pulling on the arm rests. The patient may have difficulty planning his movements in order to roll to his side and then sit up on the edge of the bed.
Productivity: Apraxia can negatively affect a patient’s ability to engage in employment, volunteering, driving, and home management, depending on the demands of the task and the severity/type of apraxia.
Leisure: Patients with apraxia may find certain leisure activities (including physical activity, crafts, shopping) to be frustrating and less enjoyable.
The terms apraxia and dyspraxia are often used interchangeably but there is a difference between these terms. The root word “praxia” means execution of voluntary motor movements; the “dys” means partial ability or partial loss; the “a” means absence of something.
Dyspraxia is the partial loss of the ability to coordinate and perform skilled purposeful movements, whereas apraxia refers to the complete loss of loss of this ability.
Dyspraxia affects a patient’s ability to plan and process motor tasks (motor planning). Although the exact causes of dyspraxia are unknown, it is thought to be caused by a disruption in the way messages from the brain are transmitted to the body. This affects a patient’s ability to perform movements in a smooth and coordinated way. Dyspraxia was formerly known and is still referred to as Developmental Coordination Disorder (DCD), which is the term to describe dyspraxia in children whose neurological development does not progress normally.
TYPES OF APRAXIA
There are several kinds of apraxia, which may occur alone or together.
The chart below therefore lists the types of apraxia, with the types of dyspraxia in italics.
|Types of Apraxia||Motor Movements||What This Looks Like Functionally||Understanding Concepts||Automatic Movements||Response to Commands||The Brain|
|Inability to execute the correct movements in response to a verbal command. Observed when patient is asked to perform specific movements or imitate gestures. There is a disturbance of voluntary movement due to a disconnection between the idea of a movement and its execution.||Unable to perform a task and imitate gestures/movements when requested to do so; can describe how a task is performed but is not able to successfully carry it out.||Understands concept of the movement needed to complete task.||Can complete automatic motor tasks because of intact kinesthetic memory.||Cannot carry out a motor task on command.||Damage to the left hemisphere.|
|Inability to perform tasks that have multiple, sequential movements such as dressing, eating, and bathing. Motor movements are not impaired but movements appear confused due to an inability to form a plan on how to sequence the movements needed to complete a task or use a tool/utensil. Movements are generally awkward, clumsy, and imprecise.||Does not know the sequence of movements needed to compete a multi-step task or use an object, struggles to use tools/ utensils e.g. using a screw- driver or cutting with a knife, not able to simulate how a task is performed.||Does not understand the sequence of movements needed to complete a task.||Can perform isolated acts or parts of movement sequences, but cannot perform complex motor actions.||Can perform simple isolated motor tasks on command but has increased difficulty as the request become more complex.||Damage to the left hemisphere.|
|Conceptual Apraxia||The function of tools is no longer understood. This results in an inability to select or use tools / objects properly because the patient does not understand the concept of tools/utensils or actions needed to use these tools/utensils.||Inability to voluntarily perform a learned task when given an objects/tools.
Semantic memory is impaired – general world knowledge that is accumulated throughout one’s life.
Content error – uses a tool as if it were another tool.
Tool-selection error: selecting the incorrect tool/objects.
Tool/object-action knowledge: uses tools /utensils inappropriately i.e. performs the incorrect action when given a tool (uses a wrench like a hammer).
Tool/object-association knowledge: unable to recall which tool is associated with a specific object (will not associate a hammer with a nail).
Mechanical knowledge: will not be able to determine the better tool to use (hammer vs. knife) in specific situations.
|Does not understand the concept of tools/utensils needed to complete a task, does not understand the actions needed to use a tool.||Can complete automatic movements that do not involve the use of tools.||Response to commands is impaired due to inability to grasp and use the correct tool.||Damage to the parietal lobe.|
|Also referred to as acquired apraxia of speech, verbal apraxia, or childhood apraxia of speech. Brain pathways involved in planning the sequence of movements involved in producing speech, are affected. The brain knows what it wants to say, but cannot properly plan and sequence the required speech sound movements. I.e. Difficulty coordinating muscle movements to pronounce words. Struggle to organize and form words that are intelligible, though the muscles involved are intact. This results in slurred speech which is hard to understand.
This type of apraxia is the inability to coordinate facial and lip movements to voluntarily perform certain movements such as licking lips, whistling, coughing, or winking. Verbal and Buccofacial apraxia are usually evaluated and treated by a SLP.
|Difficulty pronouncing words and moving oral-facial muscles to produce a co-ordinated movement e.g. winking.
Can usually understand what is being said and able to follow instructions but has difficulty communicating.
|Typically understands language much better than they are able to use it.||Difficulty completing automatic movements of the oral-facial area.||May struggle to perform a movement when asked to. E.g. stick tongue out||Damage to the linguistic-conceptual system.|
|Inability to apply well-known and practiced skills to a new situation e.g. drawing a picture of a simple object from memory. Inability to copy and draw simple figures, and build simple constructions||The patient struggles with drawing, copying, or constructing; will have body schema and meal prep difficulty.||NOT able to put an object together that has unattached pieces.||Cannot produce a design spontaneously.||Cannot produce a design on command.||Damage to either cerebral hemisphere.|
|Dressing Apraxia||The patient is not able to get dressed because of difficulty with body scheme as well as spatial relations. Can put clothes on but cannot program the appropriate movement sequences. Therefore, a coat goes on back-to-front, or socks over shoes.||The patient has difficulty orienting clothes when dressing (i.e. will put clothing on backwards or upside down).||Understands basic concepts but cannot problem solve.||Cannot complete automatic movements related to dressing.||Can respond to commands but has difficulty following through with dressing tasks.||Posterior parietal lesion, especially in right hemisphere.|
The word “apraxia” is also often confused with other neurological terms such as: ataxia, aphasia and dysmetria. The cerebellum contains more neurons than any other region in the human brain and plays a major role in motor control. Dysfunction of the cerebellum typically cause ataxia, dysmetria and tremor.
Ataxia is defined as the presence of abnormal, uncoordinated voluntary movements. Many symptoms of Ataxia can mimic those of being drunk – slurred speech, stumbling, falling, and incoordination.
Dysmetria is a lack of accuracy in voluntary movements. Patients either overshoot (hypermetria) or undershoot (hypometria) the aimed target during voluntary goal-directed tasks. They have difficulty controlling power, speed, and accuracy of movement. A patient may reach too far or not reach far enough when attempting to grasp an object; may walk into walls or doorways; may miss-estimate the distance to the seat of a chair and may fall as a result. The patient understands the concept of the movement needed to complete a task. the patient can respond to commands but may have difficulty following through with tasks.
Tremor refers to an involuntary, rhythmic, oscillatory movement of a body part.
Aphasia is defined as a language disorder that affects production and/or comprehension of written or spoken language.
APRAXIA QUICK REFERENCE
For a movement to be executed, its picture must be retrieved and activated and then be associated via cortical projections with the relevant motor engrams in the prefrontal regions. From here the information passes to the primary motor cortex before being fed down the corticospinal tracts. For the right upper limb to move the information remains contained within the left hemisphere, but for the left upper limb to move the information from the left parietal lobe must first be sent to the right prefrontal and frontal regions through the corpus callosum.
|Types of Apraxia||Description||Examples|
“Copy what I am doing”
|An inability to carry out a motor act on verbal command or imitation but can perform the task when using the actual object, in context.
The patient can conceptualize but not actually execute the action, demonstrating spared recognition of tools but deficient ability to use them appropriately on command or to imitate actions of using the tools.
|Traditionally characterized by deficits in properly performing tool-use pantomimes (e.g. pretending to use a hammer) and communicative gestures (e.g. waving goodbye).
Performing tool-use pantomimes- transitive act pantomime
• The patient describes how to use a spoon but is not able to demonstrate using a spoon. Assessed by asking the patient to, “Show me how you would use a spoon”.
• The patient is unable to mime the action of brushing his teeth on request but is observed using a toothbrush correctly when he is performing grooming activities.
|A disorder involving the motor planning and sequencing of complex motor acts – the patient appears to have lost the overall concept of how to proceed in order to complete a complex motor task. The patient is able to carry out individual motor acts but cannot complete a hierarchical sequence of a complete act.
|Characterized by an inability to conceptualize a multi-step task, despite intact identification of tools. This is illustrated when a patient is presented with a stamp and an envelope, the patient is able to name the objects correctly, but is unable to demonstrate how to mail an envelope using these objects.
• Asking a patient to strike a match against a matchbox-
• Functionally, a patient with ideational apraxia will be unable to cook a meal, make-up a bed, go shopping for groceries.
||The function of tools is no longer understood. The patient may misuse objects, have difficulty matching objects and actions (cannot select the proper tools to perform a task), be unaware of the mechanical advantage afforded by tools.||• Fails to describe the function of a tool
• Unable to point out a tool when its function is described by the examiner
• Misusing object – using a comb as a toothbrush
• Given the option of using either the camera or mirror to take a photo. By not knowing which tool to select, indicates that patient does not know the function of either the camera nor the mirror
• When a partially driven nail is shown, the patient may select a pair of scissors rather than a hammer from an array of tools to complete the action
|The term constructional disorder is now favored over the previously used term of two- and three-dimensional constructional apraxia since the deficit does not clearly fall within the definition of apraxia. Constructional disorder refers to the inability to organize or assemble parts into a whole, as in putting together block designs (three-dimensional) or drawings (two-dimensional).
The primary deficit in constructional disorder appears to involve the ability to perceive and imagine geometrical relations- the ability to organize and manually manipulate spatial information to make a design.
|• Inability to draw a picture of a simple object from memory
• Inability to copy and draw simple figures
• Inability to build and copy simple constructions
Different types of constructional disorders as determined by the location of brain insult. In general, patients with right hemisphere impairment make more coordinate type errors (e.g., distance and angular distortions), whereas those with left hemispheric impairment tend to make errors with pattern reversals
|Dressing Apraxia||Dressing apraxia is the inability to plan effective motor actions required during the complex perceptual task of dressing oneself. It signifies a feature of the impaired tactile and visuospatial coordination plus hemineglect rather than the loss of the ability to use tools. i.e. visuospatial deficits which result in difficulty dressing
|Tested by asking the patient to wear a jacket with the sleeves deliberately turned inside out.
Observing patient getting dressed:
Ideational vs Conceptual Apraxia
Ideational apraxia has been defined as an impairment in performing tasks that required a sequence of several acts with tools and objects (e.g. prepare a letter for mailing). However, some authors also use the term to denote a failure to use single tools appropriately. To overcome this confusion, restricting the term ideational apraxia has been suggested to be used for a failure to conceive a series of acts leading to an action goal. Conceptual Apraxia was therefore introduced to refer to a loss of knowledge of how objects are used. However, a strict difference between ideational and conceptual apraxia is not always feasible.
Understanding dressing apraxia
Dressing Apraxia is usually associated with a posterior parietal lesion, especially involving the right hemisphere. If there is a deficit exclusively involving dressing the left side of the body, this would likely be a manifestation of hemineglect.
Visuospatial dysfunction appears to be the underlying deficit in dressing apraxia. Therefore, errors attributable to dressing apraxia include inability to orient the garment correctly, to align it correctly to the body, and to properly introduce the arms/legs into the sleeves/trousers.
Impaired tactile and visuospatial coordination plus a degree of hemineglect may explain why some patients with right parietal lesions have long-term significant difficulty with dressing.
A different type of dressing difficulty may be evident in some patients who appear to have difficulty executing a complex sequence of dressing tasks, as seen when a patient is in a confused state. However, these patients can usually manage one piece of clothing at a time whereas patients with dressing apraxia cannot.
Video: Apraxia case study- dressing apraxia, hemi-neglect.
|Ideomotor apraxia||Gesturing and pantomime, on verbal command.||Can conceptualize but not execute the action upon request. Can execute spontaneous gestures and a one step motor task when the environmental context induces automatic response.|
|Ideational apraxia||Sequencing multi-step tasks.||Problem planning and carrying out the steps of a task in the proper order/sequence.||
|Conceptual disorder||Knowledge of tool function and tool-object association||Difficulty selecting adequate tool for specific action||
|Constructional disorder||Copying 2D drawings and 3D constructions.||Struggles with activities that require arranging, building, drawing. Difficulty with the manipulation of objects in space.||
|Dressing apraxia||Visuospatial coordination plus hemineglect.||Visuospatial difficulties result in an inability to orient garments correctly, to align them correctly to the body.|