Apraxia

Original Editor - Shreya Pavaskar

Top Contributors - Nupur Smit Shah, Niha Mulla, Shreya Pavaskar, Lucinda hampton and Alexandra Stead

Introduction

Apraxia is caused by damage to the brain (specifically the posterior parietal cortex and/or corpus callosum), characterised by an inability to carry out learned, purposeful movements with intact motor, sensory or co-ordination. Additionally, it involves impairements in production of gesture and tool use. Although the intention to move is present, the execution of the movement is not achievable. Praxis is the ability to perform skilled and learned movements, essential during daily living. It requires different aspects of cognition and inability to perform such movements is known as apraxia.

Relevant Anatomy

The frontal lobe plays a key role in initiating and controlling voluntary movement, expressive language and the management of higher-level executive functions.

The cerebellum stores and updates motor information and plays a significant role in correcting errors in learned movements. This is mediated by a modifiable synapse at the Purkinje cell.

Causes

Damage to the cells of the premotor frontal cortex of either hemisphere, the left inferior parietal lobe, and corpus callosum can lead to apraxia. This condition is more evident with left hemisphere damage than right and is commonly seen with aphasia. Left hemisphere stroke and dementia are the most common causes followed by traumatic brain injury or acute neurological insults. It is also seen in brain tumours and other neurodegenerative conditions such as corticobasal syndrome and progressive supranuclear palsy. Oculomotor apraxia, the clinical feature of impaired voluntary movement of saccadic eye movements is directly linked with genetic mutations in the literature.

Signs and symptoms

The following section mentions the signs and symptoms associated with apraxia:

• Inability to perform a movement when requested, despite the absence of paralysis.
• Able to understand verbal commands, but unable to perform the movement.
• Movements are clumsy and inappropriate to the task.
• Involuntary movements are seen often.
• Apraxia can occur with aphasia, a loss of the ability to understand or use language.

Types of apraxia

Ideational apraxia

It is a disorder of motor planning in which purposeful actions cannot be performed either spontaneously or on command. Isolated components of a task is carried out but unable to combine them into a complete sequenced act. Furthermore, verbal description of an activity is not carried out. Patients have the tendency to misuse objects, unaware of mechanical advantage afforded by tools and unable to judge whether the gesture is well or ill informed. This is due to combination of executive, language and memory limitations or due to a general limitation in cognitive resources.

Cause

Ideational apraxia is thought to be associated with lesions of dominant parietal lobe, dementia or delirium. The deficit may occur in conjunction with diffuse brain damage, such as that in cerebral arteriosclerosis.

Example

When presented in the clinic with a toothbrush and toothpaste and asked to brush their teeth, the patient keeps the tube of toothpaste in the mouth, or try to apply toothpaste on the toothbrush without removing the cap.

Ideomotor apraxia

Ideomotor apraxia is an impaired performance of skilled motor acts despite intact sensory, motor and language function. The patient is unable to produce a movement on command and able to perform it spontaneously. Thus, habitual tasks are performed without commands and often perseverates.

There is demonstration of spatiotemporal errors like impaired timing, sequencing of movements and abnormal movement amplitude, hand configuration and limb orientation in space. They use the limb itself as the object rather than demonstrating how the object is to be used. The same acts can be performed without difficulty in daily life, and this phenomenon is known as voluntary-automatic dissociation.

Performance may differ according to gesture type: transitive (involving an object, e.g. using a hammer) versus intransitive (e.g. waving goodbye); meaningful (e.g. mimicking a familiar gesture such as rubbing one’s chin) versus meaningless (e.g. mimicking a novel gesture such as placing the dorsum of the hand against the contralateral cheek).

Cause

From lesions in the left, dominant hemisphere. There is evidence that both frontal lesions and posterior parietal lesions can lead to apraxia.

Example

The patient may be unable to walk when asked to do so. However, if a cup of coffee is placed on a table at the other end of the room and the patient is told, “Please have some coffee,” they are likely to cross the room to fetch it.

Buccofacial apraxia/Orofacial apraxia

Buccofacial apraxia is associated with the non-fluent/agrammatic variant of primary progressive aphasia and is characterised by difficulty performing purposeful movements involving facial muscles around the mouth. The patient cannot voluntarily move the muscles of the larynx, pharynx, tongue, lips and cheeks despite preserved automatic movement of the same muscles. There is difficulty in responding to commands such as “pretend to blow out a candle”. When asked to blow a candle, he fails, but blows it when a lit match is brought near.

Cause

Buccofacial apraxia results from lesions in the frontal and central opercula, the anterior insula, and a small area of the superior temporal gyrus (adjacent to the frontal and central opercula). Although buccofacial apraxia often coexists with Broca's aphasia, it can occur independently. It is observed in stroke, Alzheimer's disease, motor neurone disease and frontotemporal dementia.

Conceptual apraxia

Patients with conceptual apraxia show impairment of object or action knowledge. They typically misuse objects, have difficulty matching objects and actions, be unaware of the mechanical advantage afforded by tools, or be unable to judge whether a gesture is well formed or not. It can be seen in patients with dementia and associated with lesions of posterior regions of the left hemisphere.

Limb kinetic apraxia

Patients with limb-kinetic apraxia perform inaccurate or clumsy distal limb movements. It is often seen in the limb contralateral to the affected hemisphere. This disorder is caused by frontal lesions and it is sometimes difficult to differentiate from concurrent limb weakness. Limb-kinetic apraxia has also been observed in patients with neurodegenerative conditions such as progressive supranuclear palsy and Parkinson’s disease.

Verbal apraxia

Verbal apraxia is a selective disturbance of the articulation of words and is often confused with orofacial apraxia.

Diagnosis

Apraxia can be diagnosed by detailed evaluation that incudes history, neurological examination and apraxia specific testing. Many patients with apraxia present with aphasia and it is challenging to distinguish. Various bedside tasks are used to evaluate apraxia which include ADLs and physical tasks. Hand gestures, finger gestures, and pantomime are used to diagnose apraxia.

• CT or MRI scans of the brain diagnose and underlying condition such as a tumour, stroke and head injury.

• Electroencephalogram (EEG) is performed to map brain activity.

Outcome measures

Outcome measures are used to check the presence/severity of apraxia, guide treatment planning and monitor changes in functional performance overtime:

• Ideomotor and Ideational Apraxia - Goodglass and Kaplan test for apraxia is composed of universally known movements, such as blowing, brushing teeth, hammering, shaving, and so on. It is based on what the authors consider a hierarchy of difficulty for patients with apraxia. Additional apraxia tests include Arnadottir OT-ADL Neuro-behavioural Evaluation (A-ONE) which is an observational assessment.
• Adult apraxia of speech - Apraxia of speech rating scale is commonly used.
• Tool-use apraxia - The Digital Tools Test evaluates correct selection and use of applications and detects motor related errors. It is used to check the proficiency of patients in choosing the right application for a given task.
• Upper Limb Apraxia - Apraxia screen of TULIA. It is a bedside tool of gestures in stroke consisting of 12 items.
• Functional Independence - Barthel Index is the standardised tool used to assess functional independence in ADL.

Differential Diagnosis

Conditions which mimic the clinical features of apraxia:

• Agnosia
• Aphasia
• Hemiparesis
• Movement disorders such as Parkinson disease and dystonia
• Alzheimer disease
• Progressive supranuclear palsy

Treatment

Physiotherapy management

Remedial approach

In the remediation of apraxia, it is advised that the therapist speak slowly and use the shortest possible sentences. One command should be given at a time, and the second command should not be given until the first task is completed. When teaching a new task, it should be broken down into its smaller parts. One component is taught at a time, physically guiding the patient through the task if necessary. It should be completed in precisely the same manner each time. When all the individual units are mastered, an attempt to combine them should be made. A great deal of repetition may be necessary. Family members must be advised to use the exact approach found to be effective in the clinic. Using the sensorimotor approach, multiple sensory inputs are used on the affected body parts to enhance the production of appropriate motor responses.

Compensatory approach

Strategy training involves teaching the patient compensatory techniques to overcome the apraxia such as use of pictures in the correct sequence to support ADL skills. It teaches the patients about the strategies to compensate for the deficits linked to apraxia. It typically focuses on improving daily activities rather than the recovery of motor impairments.

Restorative approach

Treatment is divided into three phases like transitive, intra-transitive symbolic and intra-transitive non-symbolic. In the first phase the patient is required to use the common tools, in the next phase a picture about transitive gesture is shown and the patient has to imitate it. In the final phase the patient is shown a picture of a common tool and is then asked to demonstrate the usage of that tool.

Summary

Apraxia is a motor disorder caused by damage mainly to the posterior parietal cortex and/or corpus collosum. The person is typically unable perform purposeful movements even though strength, sensation and coordination are intact. Production of gesture and the tool use are also affected. Main types include ideational, ideomotor, buccofacial, conceptual, limb-kinetic and verbal. Diagnosis is made by clinical evaluation, neurological assessment and bed side tasks. Speech and occupational therapists play very important role to treat apraxia. Physiotherapy management includes giving slow and short commands, repeating them identically and involving family members.